PARTICULES FORMEES IN SITU GALVANIQUEMENT ACTIVES POUR OUTILS DE DISSOLUTION A VITESSE CONTROLEE

GALVANICALLY-ACTIVE IN SITU FORMED PARTICLES FOR CONTROLLED RATE DISSOLVING TOOLS

Abrégé anglais

A castable, moldable, and/or extrudable structure using a metallic primary
alloy. One or more
additives are added to the metallic primary alloy so that in situ galvanically-
active reinforcement
particles are formed in the melt or on cooling from the melt. The composite
contains an optimal
composition and morphology to achieve a specific galvanic corrosion rate in
the entire composite.
The in situ formed galvanically-active particles can be used to enhance
mechanical properties of
the composite, such as ductility and/or tensile strength. The final casting
can also be enhanced by
heat treatment, as well as deformation processing such as extrusion, forging,
or rolling, to further
improve the strength of the final composite over the as-cast material.

Revendications

What is claimed:
1. A method of controlling the dissolution properties of a magnesium or a
magnesium alloy
comprising of the steps of:
heating the magnesium or a magnesium alloy to a point above its solidus
temperature;
adding an additive to said magnesium or magnesium alloy while said magnesium
or
magnesium alloy is above said solidus temperature of magnesium or magnesium
alloy to form a
mixture, said additive including one or more first additives having an
electronegativity of greater
than 1.5, said additive constituting about 0.05-45 wt.% of said mixture;
dispersing said additive in said mixture while said magnesium or magnesium
alloy is above
said solidus temperature of magnesium or magnesium alloy; and,
cooling said mixture to form a magnesium composite, said magnesium composite
including
in situ precipitation of galvanically-active intermetallic phases.
2. The method as defined in claim 1, wherein said first additive has an
electronegativity
of greater than 1.8.
3. The method as defined in claim 1 or 2, including the step of controlling
a size of said
in situ precipitated intermetallic phase by controlled selection of a mixing
technique during said
dispersion step, controlling a cooling rate of said mixture, or combinations
thereof
4. The method as defined in any one of claims 1-3, wherein said magnesium
or
magnesium alloy is heated to a temperature that is less than said melting
point temperature of at
least one of said additives.
5. The method as defined in any one of claims 1-4, wherein said magnesium
or
magnesium alloy is heated to a temperature that is greater than said melting
point temperature of at
least one of said additives.
6. The method as defined in any one of claims 1-5, wherein said additive
includes one
or more metals selected from the group consisting of calcium, copper, nickel,
cobalt, bismuth, silver,
gold, lead, tin, antimony, indium, arsenic, mercury, and gallium.
47

7. The method as defined in claim 6, wherein said additive includes one or
more metals
selected from the group consisting of calcium, copper, nickel, cobalt,
bismuth, tin, antimony,
indium, and gallium.
8. The method as defined in any one of claims 1-7, wherein said additive
includes one
or more second additives that have an electronegativity of less than 1.25.
9. The method as defined in claim 8, wherein said second additive includes
one or more
metals selected from the group consisting of strontium, barium, potassium,
sodium, lithium, cesium,
and the rare earth metals such as yttrium, lanthanum, samarium, europium,
gadolinium, terbium,
dysprosium, holmium, and ytterbium.
10. The method as defined in any one of claims 1-9, wherein said additive
is formed of
a single composition, and has an average particle diameter size of about 0.1-
500 microns.
11. The method as defined in any one of claims 1-10, wherein said at least
a portion of
said additive remains at least partially in still solution in an a-magnesium
phase of said magnesium
composite.
12. The method as defined in any one of claims 1-11, wherein said magnesium
alloy
includes over 50 wt.% magnesium and one or more metals selected from the group
consisting of
aluminum, boron, bismuth, zinc, zirconium, and manganese.
13. The method as defined in any one of claims 1-12, wherein said magnesium
alloy
includes over 50 wt.% magnesium and one or more metals selected from the group
consisting of
aluminum in an amount of about 0.5-10 wt.%, zinc in amount of about 0.1-6
wt.%, zirconium in an
amount of about 0.01-3 wt.%, manganese in an amount of about 0.15-2 wt.%;
boron in amount of
about 0.0002-0.04 wt.%, and bismuth in amount of about 0.4-0.7 wt.%.
14. The method as defined in any one of claims 1-13, wherein said magnesium
alloy
includes over 50 wt.% magnesium and one or more metals selected from the group
consisting of
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aluminum in an amount of about 0.5-10 wt.%, zinc in amount of about 0.1-3
wt.%, zirconium in an
amount of about 0.01-1 wt.%, manganese in an amount of about 0.15-2 wt.%;
boron in amount of
about 0.0002-0.04 wt.%, and bismuth in amount of about 0.4-0.7.wt %.
15. The method as defined in any one of claims 1-14, including the step of
solutionizing
said magnesium composite at a temperature above 300°C and below a
melting temperature of said
magnesium composite to improve tensile strength, ductility, or combinations
thereof of said
magnesium composite.
16. The method as defined in any one of claims 1-15, including the step of
forming said
magnesium composite into a final shape or near net shape by a) sand casting,
permanent mold
casting, investment casting, shell molding, or other pressureless casting
technique at a temperature
above 730°C, 2) using either pressure addition or elevated pouring
temperatures above 710°C, or
3) subjecting the magnesium composite to pressures of 2000-20,000 psi through
the use of squeeze
casting, thixomolding, or high pressure die casting techniques.
17. The method as defined in any one of claims 1-16, including the step of
aging said
magnesium composite at a temperature of above 100°C and below
300°C to improve tensile strength
of said magnesium composite.
18. The method as defined in any one of claims 1-17, wherein said magnesium
composite has a hardness above 14 Rockwell Harness B.
19. The method as defined in any one of claims 1-18, wherein said magnesium
composite has a dissolution rate of at least 5 mg/cm2-hr. in 3% KCl at
90°C.
20. The method as defined in any one of claims 1-19, wherein said additive
metal
includes about 0.05-35 wt.% nickel.
21. The method as defined in any one of claims 1-20, wherein said additive
includes
about 0.05-35 wt.% copper.
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22. The method as defined in any one of claims 1-21, wherein said additive
includes
about 0.05-35 wt.% antimony.
23. The method as defined in any one of claims 1-22, wherein said additive
includes
about 0.05-35 wt.% gallium.
24. The method as defined in any one of claims 1-23, wherein said additive
includes
about 0.05-35 wt.% tin.
25. The method as defined in any one of claims 1-24, wherein said additive
includes
about 0.05-35 wt.% bismuth.
26. The method as defined in any one of claims 1-25, wherein said additive
includes
about 0.05-35 wt.% calcium.
27. The method as defined in any one of claims 1-26, further including the
step of rapidly
solidifying said magnesium composite by atomizing the molten mixture and then
subjecting the
atomized molten mixture to ribbon casting, gas and water atomization, pouring
into a liquid, high
speed machining, saw cutting, or grinding into chips, followed by powder or
chip consolidation
below its liquidus temperature.
28. A magnesium composite that includes in situ precipitation of
galvanically-active
intermetallic phases comprising a magnesium or a magnesium alloy and an
additive constituting
about 0.05-45 wt.% of said magnesium composite, said magnesium having a
content in said
magnesium composite that is greater than 50 wt.%, said additive forming metal
composite particles
or precipitant in said magnesium composite, said metal composite particles or
precipitant forming
said in situ precipitation of said galvanically-active intermetallic phases,
said additive including one
or more first additives having an electronegativity of greater than 1.5.
29. The magnesium composite as defined in claim 28, further including one
or more
second additives having an electronegativity of less than 1.25.

30. The magnesium composite as defined in claim 28 or 29, wherein said
first additive
has an electronegativity of greater than 1.8.
31. The magnesium composite as defined in any one of claims 28-30, wherein
said first
additive includes one or more metals selected from the group consisting of
copper, nickel, cobalt,
bismuth, silver, gold, lead, tin, antimony, indium, arsenic, mercury, and
gallium.
32. The magnesium composite as defined in any one of claims 28-31, wherein
said first
additive includes one or more metals selected from the group consisting of
copper, nickel, cobalt,
bismuth, tin, antimony, indium, and gallium.
33. The magnesium composite as defined in any one of claims 28-32, wherein
said
second additive includes one or more metals selected from the group consisting
of calcium,
strontium, barium, potassium, sodium, lithium, cesium, and the rare earth
metals such as yttrium,
lanthanum, samarium, europium, gadolinium, terbium, dysprosium, holmium, and
ytterbium.
34. The magnesium composite as defined in any one of claims 28-33, wherein
said
magnesium alloy includes over 50 wt.% magnesium and one or more metals
selected from the group
consisting of aluminum, boron, bismuth, zinc, zirconium, and manganese.
35. The magnesium composite as defined in any one of claims 28-34, wherein
said
magnesium alloy includes over 50 wt.% magnesium and one or more metals
selected from the group
consisting of aluminum in an amount of about 0.5-10 wt.%, zinc in amount of
about 0.1-3 wt.%,
zirconium in an amount of about 0.01-1 wt.%, manganese in an amount of about
0.15-2 wt.%, boron
in amount of about 0.0002-0.04 wt.%, and bismuth in amount of about 0.4-0.7
wt.%.
36. The magnesium composite as defined in any one of claims 28-35, wherein
said
additive includes about 0.05-45 wt.% nickel.
37. The magnesium composite as defined in any one of claims 28-36, wherein
said first
additive includes about 0.05-45 wt.% copper.
51

38. The magnesium composite as defined in any one of claims 28-37, wherein
said first
additive includes about 0.05-45 wt.% cobalt.
39. The magnesium composite as defined in any one of claims 28-38, wherein
said first
additive includes about 0.05-45 wt.% antimony.
40. The magnesium composite as defined in any one of claims 28-39, wherein
said first
additive includes about 0.05-45 wt.% gallium.
41. The magnesium composite as defined in any one of claims 28-40, wherein
said first
additive includes about 0.05-45 wt.% tin.
42. The magnesium composite as defined in any one of claims 28-41, wherein
said first
additive includes about 0.05-45 wt.% bismuth.
43. The magnesium composite as defined in any one of claims 28-42, wherein
said
second additive includes 0.05-35 wt.% calcium.
44. The magnesium composite as defined in any one of claims 28-43, wherein
said
magnesium composite has a hardness above 14 Rockwell Harness B.
45. The magnesium composite as defined in any one of claims 28-44, wherein
said
magnesium composite has a dissolution rate of at least 5 mg/cm2-hr. in 3% KCl
at 90°C.
46. The magnesium composite as defined in any one of claims 28-45, wherein
a
dissolution rate of said magnesium composite is about 5-300 mg/cm2-hr in 3
wt.% KCl water
mixture at 90° C.
47. The magnesium composite as defined in any one of claims 28-46, wherein
said
magnesium composite is subjected to a surface treatment to improve a surface
hardness of said
52

magnesium composite, said surface treatment including peening, heat treatment,
aluminizing, or
combinations thereof
48. The magnesium composite as defined in any one of claims 28-47, wherein
a
dissolution rate of said magnesium composite is controlled by an amount and
size of said in situ
formed galvanically-active particles whereby smaller average sized particles
of said in situ formed
galvanically-active particles, a greater weight percent of said in situ formed
galvanically-active
particles in said magnesium composite, or combinations thereof increases said
dissolution rate of
said magnesium composite.
49. A dissolvable component for use in downhole operations that is fully or
partially
formed of a magnesium composite, said dissolvable component including a
component selected
from the group consisting of sleeve, frac ball, hydraulic actuating tooling,
mandrel, slip, grip, ball,
dart, carrier, tube, valve, valve component, plug, or other downhole well
component, said
magnesium composite includes in situ precipitation of galvanically-active
intermetallic phases
comprising a magnesium or a magnesium alloy and an additive constituting about
0.05-45 wt.% of
said magnesium composite, said magnesium having a content in said magnesium
composite that is
greater than 50 wt.%, said additive forming metal composite particles or
precipitant in said
magnesium composite, said metal composite particles or precipitant forming
said in situ
precipitation of said galvanically-active intermetallic phases, said additive
including one or more
first additives having an electronegativity of greater than 1.5.
50. The dissolvable component as defined in claim 49, further including one
or more
second additives having an electronegativity of less than 1.25.
51. The dissolvable component as defined in claim 49 or 50, wherein said
first additive
has an electronegativity of greater than 1.8.
52. The dissolvable component as defined in any one of claims 49-51,
wherein said first
additive includes one or more metals selected from the group consisting of
copper, nickel, cobalt,
bismuth, silver, gold, lead, tin, antimony, indium, arsenic, mercury, and
gallium.
53

53. The dissolvable component as defined in any one of claims 49-52,
wherein said first
additive includes one or more metals selected from the group consisting of
copper, nickel, cobalt,
bismuth, tin, antimony, indium, and gallium.
54. The dissolvable component as defined in any one of claims 49-53,
wherein said
second additive includes one or more metals selected from the group consisting
of calcium,
strontium, barium, potassium, sodium, lithium, cesium, and the rare earth
metals such as yttrium,
lanthanum, samarium, europium, gadolinium, terbium, dysprosium, holmium, and
ytterbium.
55. The dissolvable component as defined in claim 54, wherein said second
additive
includes 0.05-35 wt.% calcium.
56. The dissolvable component as defined in any one of claims 49-55,
wherein said
magnesium alloy includes over 50 wt.% magnesium and one or more metals
selected from the group
consisting of aluminum, boron, bismuth, zinc, zirconium, and manganese.
57. The dissolvable component as defined in any one of claims 49-56,
wherein said
magnesium composite has a hardness above 14 Rockwell Harness B.
58. The dissolvable component as defined in any one of claims 49-57,
wherein said
magnesium composite has a dissolution rate of at least 5 mg/cm2-hr. in 3% KCl
at 90°C.
59. The dissolvable component as defined in any one of claims 49-58,
wherein said
magnesium composite has a dissolution rate of at least 10 mg/cm2-hr in a 3%
KCl solution at 90°C.
60. The dissolvable component as defined in any one of claims 49-59,
wherein said
magnesium composite has a dissolution rate of at least 20 mg/cm2-hr in a 3%
KCl solution at 65°C.
61. The dissolvable component as defined in any one of claims 49-60,
wherein said
magnesium composite has a dissolution rate of at least 1 mg/cm2-hr in a 3% KCl
solution at 65°C.
54

62. The dissolvable component as defined in any one of claims 49-61,
wherein said
magnesium composite has a dissolution rate of at least 100 mg/cm2-hr in a 3%
KCl solution at 90°C.
63. The dissolvable component as defined in any one of claims 49-62,
wherein said
magnesium composite has a dissolution rate of at least 45 mg/cm2/hr. in 3 wt.%
KCl water mixture
at 90°C and up to 325 mg/cm2/hr. in 3 wt.% KCl water mixture at
90°C.
64. The dissolvable component as defined in any one of claims 49-63,
wherein said
magnesium composite has a dissolution rate of up to 1 mg/cm2/hr. in 3 wt.% KCl
water mixture at
21°C.
65. The dissolvable component as defined in any one of claims 49-64,
wherein said
magnesium composite has a dissolution rate of at least 90 mg/cm2-hr. in 3% KCl
solution at 90°C.
66. The dissolvable component as defined in any one of claims 49-65,
wherein said
magnesium composite has a dissolution rate of at least a rate of 0.1 mg/cm2-
hr. in 0.1% KCl solution
at 90°C.
67. The dissolvable component as defined in any one of claims 49-66,
wherein said
magnesium composite has a dissolution rate of a rate of <0.1 mg/cm2-hr. in
0.1% KCI solution at
75°C.
68. The dissolvable component as defined in any one of claims 49-67,
wherein said
magnesium composite has a dissolution rate of, a rate of <0.1 mg/cm2-hr. in
0.1% KCl solution at
60°C.
69. The dissolvable component as defined in any one of claims 49-68,
wherein said
magnesium composite has a dissolution rate of <0.1 mg/cm2-hr. in 0.1% KCl
solution at 45°C.
70. The dissolvable component as defined in any one of claims 49-69,
wherein said
magnesium composite has a dissolution rate of at least 30 mg/cm2-hr. in 0.1%
KCl solution at 90°C.

71. The dissolvable component as defined in any one of claims 49-70,
wherein said
magnesium composite has a dissolution rate of at least 20 mg/cm2-hr. in 0.1%
KCl solution at 75°C.
72. The dissolvable component as defined in any one of claims 49-71,
wherein said
magnesium composite has a dissolution rate of at least 10 mg/cm2-hr. in 0.1%
KCl solution at 60°C.
73. The dissolvable component as defined in any one of claims 49-72,
wherein said
magnesium composite has a dissolution rate of at least 2 mg/cm2-hr. in 0.1%
KCl solution at 45°C.
74. The dissolvable component as defined in any one of claims 49-73,
wherein said
metal composite particles or precipitant in said magnesium composite has a
solubility in said
magnesium of less than 5%.
75. The dissolvable component as defined in any one of claims 49-74,
wherein said
magnesium alloy includes over 50 wt.% magnesium and one or more metals
selected from the group
consisting of aluminum, boron, bismuth, zinc, zirconium, and manganese.
76. The dissolvable component as defined in any one of claims 49-75,
wherein said
magnesium alloy includes over 50 wt.% magnesium and one or more metals
selected from the group
consisting of aluminum in an amount of about 0.5-10 wt.%, zinc in an amount of
about 0.1-6 wt.%,
zirconium in an amount of about 0.01-3 wt.%, manganese in an amount of about
0.15-2 wt.%, boron
in an amount of about 0.0002-0.04 wt.%, and bismuth in amount of about 0.4-0.7
wt.%.
77. The dissolvable component as defined in any one of claims 49-76,
wherein said
magnesium alloy includes over 50 wt.% magnesium and one or more metals
selected from the group
consisting of aluminum in an amount of about 0.5-10 wt.%, zinc in an amount of
about 0.1-3 wt.%,
zirconium in an amount of about 0.01-1 wt.%, manganese in an amount of about
0.15-2 wt.%, boron
in an amount of about 0.0002-0.04 wt.%, and bismuth in an amount of about 0.4-
0.7 wt.%.
78. The dissolvable component as defined in any one of claims 49-77,
wherein said
magnesium alloy includes at least 85 wt.% magnesium and one or more metals
selected from the
56

group consisting of 0.5-10 wt.% aluminum, 0.05-6 wt.% zinc, 0.01-3 wt.%
zirconium, and 0.15-2
wt.% manganese.
79. The dissolvable component as defined in any one of claims 49-77,
wherein said
magnesium alloy includes 60-95 wt.% magnesium and 0.01-1 wt.% zirconium.
80. The dissolvable component as defined in any one of claims 49-79,
wherein said
magnesium alloy includes 60-95 wt.% magnesium, 0.5-10 wt.% aluminum, 0.05-6
wt.% zinc, and
0.15-2 wt.% manganese.
81. The dissolvable component as defined in any one of claims 49-80,
wherein said
magnesium alloy includes 60-95 wt.% magnesium, 0.05-6 wt.% zinc, and 0.01-1
wt.% zirconium.
82. The dissolvable component as defined in any one of claims 49-81,
wherein said
magnesium alloy includes over 50 wt.% magnesium and one or more metals
selected from the group
consisting of 0.5-10 wt.% aluminum, 0.1-2 wt.% zinc, 0.01-1 wt.% zirconium,
and 0.15-2 wt.%
manganese.
83. The dissolvable component as defined in any one of claims 49-82,
wherein said
magnesium alloy includes over 50 wt.% magnesium and one or more metals
selected from the group
consisting of 0.1-3 wt.% zinc, 0.01-1 wt.% zirconium, 0.05-1 wt.% manganese,
0.0002-0.04 wt.%
boron, and 0.4-0.7 wt.% bismuth.
84. A degradable magnesium alloy including 1-15 wt.% aluminum and a
dissolution
enhancing intermetallic phase between magnesium and cobalt, nickel, and/or
copper with the alloy
composition containing 0.05-25 wt.% cobalt, nickel, and/or copper, and 0.1-15
wt.% calcium.
85. A degradable magnesium alloy including 1-15 wt.% aluminum and a
dissolution
enhancing intermetallic phase between magnesium and cobalt, nickel, and/or
copper with the alloy
composition containing 0.05-25 wt.% cobalt, nickel, and/or copper, and 0.1-15
wt.% of calcium,
strontium, barium and/or scandium.
57

86. A degradable magnesium alloy wherein the alloy composition includes 0.5-
8 wt.%
calcium, 0.05-20 wt.% nickel, 3-11 wt.% aluminum, and 50-95 wt.% magnesium and
the alloy
degrades at a rate that is greater than 5 mg/cm2-hr. at temperatures below
90°C in fresh water (water
with less than 1000ppm salt content).
87. A degradable magnesium alloy wherein the alloy composition includes 0-2
wt.%
zinc, 0.5-8 wt.% calcium, 0.05-20 wt.% nickel, 5-11wt.% aluminum, and 50-95
wt.% magnesium
and the alloy degrades at a rate that is greater than 1 mg/cm2-hr. at
temperatures below 45°C in fresh
water (water with less than 1000ppm salt content).
88. The degradable alloy as defined in any one of claims 84-87, wherein
said calcium,
strontium and/or barium addition forms an aluminum-calcium phase, an aluminum-
strontium phase
and/or an aluminum-barium phase that leads to an alloy with a higher incipient
melting point and
increased corrosion rate.
89. The degradable alloy as defined in any one of claims 84-88, wherein the
calcium
creates an aluminum-calcium (e.g., AlCa2 phase) as opposed to a magnesium-
aluminum phase (e.g.,
Mg17Al12 phase) to thereby enhance the speed of degradation of the alloy when
exposed to a
conductive fluid vs. the common practice of enhancing the speed of degradation
of an aluminum-
containing alloy by reducing the aluminum content to reduce the amount of
Mg17Al12 in the alloy.
90. The degradable alloy as defined in any one of claims 84-89, wherein the
calcium
addition forms an aluminum-calcium phase that increases the ratio of
dissolution of intermetallic
phase to the base magnesium, and thus increases the dissolution rate of the
alloy.
91. The degradable alloy as defined in any one of claims 84-90, wherein the
calcium
addition forming the aluminum-calcium phase reduces the salinity required for
the same dissolution
rate by over 2x at 90°C in a saline solution.
92. The degradable alloy as defined in any one of claims 84-91, wherein the
calcium
addition increases the incipient melting temperature of the degradable alloy,
thus the alloy can be
58

extruded at higher speeds and thinner walled tubes can be formed as compared
to a degradable alloy
without calcium additions.
93. The degradable alloy as defined in any one of claims 84-92, wherein the
mechanical
properties of tensile yield and ultimate strength are not lowered by more than
10% or are enhanced
as compared to an alloy without calcium addition.
94. The degradable alloy as defined in any one of claims 84-93, wherein the
elevated
mechanical properties of yield strength and ultimate strength of the alloy at
temperatures above
100°C are increased by more than 5% due to the calcium addition.
95. The degradable alloy as defined in any one of claims 84-94, wherein the
galvanically
active phase is present in the form of an LPSO (Long Period Stacking Fault)
phase such as Mg12 Zn1-
x Ni x RE (where RE is a rare earth element) and that phase is 0.05-5 wt.% of
the final alloy
composition.
96. The degradable alloy as defined in any one of claims 84-95, wherein the
mechanical
properties at 150°C are at least 24 ksi tensile yield strength, and are
not less than 20% lower than
the mechanical properties at room temperature (77°F).
97. The degradable alloy as defined in any one of claims 84-96, wherein the
dissolution
rate at 150°C in 3% KCl brine is 10-150 mg/cm2/hr.
98. The degradable alloy as defined in any one of claims 84-97, wherein the
alloy
includes 2-4 wt.% yttrium, 2-5 wt.% gadolinium, 0.3-4 wt.% nickel, and 0.05-4
wt.% zinc.
99. The degradable alloy as defined in any one of claims 84-98, which alloy
includes
0.1-0.8 wt.% manganese and/or zirconium.
100. A tool that includes the degradable alloy as defined in any one of claims
84-99, for
use in downhole applications such as pressure segmentation, or zonal control.
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101. The tool as defined in claim 100, for zonal or pressure isolation in a
downhole
component or tool.
102. A method of creating the degradable alloy defined in any one of claims 84-
101,
wherein a base dissolution enhanced magnesium alloy is melted and calcium is
added as metallic
calcium above the liquids of the magnesium-aluminum phase and the aluminum
preferentially
forms AlCa2 vs. Mg1Al12 during solidification of the alloy.
103. A method of creating the degradable alloy defined in any one of claims 84-
102,
wherein the method of adding calcium is in the form of an oxide or salt that
is reduced by the molten
melt vs. adding the calcium as a metallic element.
104. A method of creating the degradable alloy defined in any one of claims 84-
103,
where said degradable alloy can be formed at double the speed or higher as
compared to an alloy
that does not include calcium due to the rise in incipient melting
temperature.

Description

GALVANICALLY-ACTIVE IN SITU FORMED PARTICLES
FOR CONTROLLED RATE DISSOLVING TOOLS
FIELD OF THE INVENTION
[0001] The invention is directed to a novel material for use as a
dissolvable structure in oil
drilling. Specifically, the invention is directed to a ball or other structure
in a well drilling or
completion operation, such as a structure that is seated in a hydraulic
operation, that can be dissolved
away after use so that that no drilling or removal of the structure is
necessary. Primarily,
dissolution is measured as the time the ball removes itself from the seat or
can become free floating
in the system. Secondarily, dissolution is measured in the time the ball is
substantially or fully
dissolved into submicron particles. Furthermore, the novel material of the
present invention can
be used in other well structures that also desire the function of dissolving
after a period of time.
The material is machinable and can be used in place of existing metallic or
plastic structures in oil
and gas drilling rigs including, but not limited to, water injection and
hydraulic fracturing.
BACKGROUND OF THE INVENTION
[0002] The ability to control the dissolution of a downhole well component
in a variety of
solutions is important to the utilization of non-drillable completion tools,
such as sleeves, frac balls,
hydraulic actuating tooling, and the like. Reactive materials for this
application, which dissolve or
corrode when exposed to acid, salt, and/or other wellbore conditions, have
been proposed for some
time. Generally, these components consist of materials that are engineered to
dissolve or corrode.
[0003] While the prior art well drill components have enjoyed modest
success in reducing well
completion costs, their consistency and ability to specifically control
dissolution rates in specific
solutions, as well as other drawbacks such as limited strength and poor
reliability, have impacted
their widespread adoption. Ideally, these components would be manufactured by
a process that is
low cost, scalable, and produces a controlled corrosion rate having similar or
increased strength as
compared to traditional engineering alloys such as aluminum, magnesium, and
iron. Ideally,
traditional heat treatments, deformation processing, and machining techniques
could be used on the
components without impacting the dissolution rate and reliability of such
components.
[0004] Prior art articles regarding calcium use in magnesium are set for in
Koltygin et al.,
"Effect of calcium on the process of production and structure of magnesium
melted by flux-free
1
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method" Magnesium and Its Alloys (2013): 540-544; Koltygin et al.,
"Development of a magnesium
alloy with good casting characteristics on the basis of Mg-Al-Ca-Mn system,
having Mg-Al2Ca
structure." Journal of Magnesium and Alloys 1 (2013): 224-229; Li et al.,
"Development of non-
flammable high strength AZ91 + Ca alloys via liquid forging and extrusion."
Materials and Design
(2016): 37-43; Cheng et al. "Effect of Ca and Y additions on oxidation
behavior of AZ91 alloy at
elevated temperatures." Transactions of Nonferrous Metals Society of China
(2009): 299-304; and
Qudong et al., "Effects of Ca addition on the microstructure and mechanical
properties of AZ91
magnesium alloy." Journal of Materials Science (2001): 3035-3040.
SUMMARY OF THE INVENTION
[0005]
The present invention is directed to a novel magnesium composite for use as a
dissolvable component in oil drilling and will be described with particular
reference to such
application. As can be appreciated, the novel magnesium composite of the
present invention can
be used in other applications (e.g., non-oil wells, etc.). In one non-limiting
embodiment, the
present invention is directed to a ball or other tool component in a well
drilling or completion
operation such as, but not limited to, a component that is seated in a
hydraulic operation that can be
dissolved away after use so that no drilling or removal of the component is
necessary. Tubes,
valves, valve components, plugs, frac balls, sleeve, hydraulic actuating
tooling, mandrels, slips,
grips, balls, darts, carriers, valve components, other downhole well
components and other shapes of
components can also be formed of the novel magnesium composite of the present
invention. For
purposes of this invention, primary dissolution is measured for valve
components and plugs as the
time the part removes itself from the seat of a valve or plug arrangement or
can become free floating
in the system. For example, when the part is a plug in a plug system, primary
dissolution occurs
when the plug has degraded or dissolved to a point that it can no long
function as a plug and thereby
allows fluid to flow about the plug. For purposes of this invention, secondary
dissolution is
measured in the time the part is fully dissolved into submicron particles. As
can be appreciated,
the novel magnesium composite of the present invention can be used in other
well components that
also desire the function of dissolving after a period of time. In one non-
limiting aspect of the
present invention, a galvanically-active phase is precipitated from the novel
magnesium composite
composition and is used to control the dissolution rate of the component;
however, this is not
required. The novel magnesium composite is generally castable and/or
machinable and can be
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used in place of existing metallic or plastic components in oil and gas
drilling rigs including, but
not limited to, water injection and hydraulic fracturing. The novel magnesium
composite can be
heat treated as well as extruded and/or forged.
[0006]
In one non-limiting aspect of the present invention, the novel magnesium
composite is
used to form a castable, moldable, or extrudable component. Non-limiting
magnesium composites
in accordance with the present invention include at least 50 wt.% magnesium.
One or more
additives are added to a magnesium or magnesium alloy to form the novel
magnesium composite
of the present invention. The one or more additives can be selected and used
in quantities so that
galvanically-active intermetallic or insoluble precipitates form in the
magnesium or magnesium
alloy while the magnesium or magnesium alloy is in a molten state and/or
during the cooling of the
melt; however, this is not required. The one or more additives can be in the
form of a pure or nearly
pure additive element (e.g., at least 98% pure), or can be added as an alloy
of two or more additive
elements or an alloy of magnesium and one or more additive elements. The one
or more additives
typically are added in a weight percent that is less than a weight percent of
said magnesium or
magnesium alloy. Typically, the magnesium or magnesium alloy constitutes about
50.1-99.9 wt.%
of the magnesium composite and all values and ranges therebetween. In one non-
limiting aspect
of the invention, the magnesium or magnesium alloy constitutes about 60-95
wt.% of the
magnesium composite, and typically the magnesium or magnesium alloy
constitutes about 70-90
wt.% of the magnesium composite. The one or more additives can be added to the
molten
magnesium or magnesium alloy at a temperature that is less than the melting
point of the one or
more additives; however, this is not required. The one or more additives
generally have an average
particle diameter size of at least about 0.1 microns, typically no more than
about 500 microns (e.g.,
0.1 microns, 0.1001 microns, 0.1002 microns ... 499.9998 microns, 499.9999
microns, SOO microns)
and include any value or range therebetween, more typically about 0.1-400
microns, and still more
typically about 10-50 microns. In one non-limiting configuration, the
particles can be less than 1
micron. During the process of mixing the one or more additives in the molten
magnesium or
magnesium alloy, the one or more additives do not typically fully melt in the
molten magnesium or
magnesium alloy; however, the one or more additives can form a single-phase
liquid with the
magnesium while the mixture is in the molten state. As can be appreciated, the
one or more
additives can be added to the molten magnesium or magnesium alloy at a
temperature that is greater
than the melting point of the one or more additives. The one or more additives
can be added
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individually as pure or substantially pure additive elements or can be added
as an alloy that is formed
of a plurality of additive elements and/or an alloy that includes one or more
additive elements and
magnesium. When one or more additive elements are added as an alloy, the
melting point of the
alloy may be less than the melting point of one or more of the additive
elements that are used to
form the alloy; however, this is not required. As such, the addition of an
alloy of the one or more
additive elements could be caused to melt when added to the molten magnesium
at a certain
temperature, whereas if the same additive elements were individually added to
the molten
magnesium at the same temperature, such individual additive elements would not
fully melt in the
molten magnesium.
(0007]
The one or more additives are selected such that as the molten magnesium
cools, newly
formed metallic alloys and/or additives begin to precipitate out of the molten
metal and form the in
situ phase to the matrix phase in the cooled and solid magnesium composite.
After the mixing
process is completed, the molten magnesium or magnesium alloy and the one or
more additives that
are mixed in the molten magnesium or magnesium alloy are cooled to form a
solid component. In
one non-limiting embodiment, the temperature of the molten magnesium or
magnesium alloy is at
least about 10 C less than the melting point of the additive that is added to
the molten magnesium
or magnesium alloy during the addition and mixing process, typically at least
about 100 C less than
the melting point of the additive that is added to the molten magnesium or
magnesium alloy during
the addition and mixing process, more typically about 100-1000 C (and any
value or range
therebetween) less than the melting point of the additive that is added to the
molten magnesium or
magnesium alloy during the addition and mixing process; however, this is not
required. As can be
appreciated, one or more additives in the form of an alloy or a pure or
substantially pure additive
element can be added to the magnesium that have a melting point that is less
than the melting point
of magnesium, but still at least partially precipitate out of the magnesium as
the magnesium cools
from its molten state to a solid state. Generally, such one or more additives
and/or one or more
components of the additives form an alloy with the magnesium and/or one or
more other additives
in the molten magnesium. The formed alloy has a melting point that is greater
than a melting point
of magnesium, thereby results in the precipitation of such formed alloy during
the cooling of the
magnesium from the molten state to the solid state. The never melted
additive(s) and/or the newly
formed alloys that include one or more additives are referred to as in situ
particle formation in the
molten magnesium composite. Such a process can be used to achieve a specific
galvanic corrosion
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rate in the entire magnesium composite and/or along the grain boundaries of
the magnesium
composite.
[0008] The invention adopts a feature that is usually a negative in
traditional casting practices
wherein a particle is formed during the melt processing that corrodes the
alloy when exposed to
conductive fluids and is imbedded in eutectic phases, the grain boundaries,
and/or even within grains
with precipitation hardening. This feature results in the ability to control
where the galvanically-
active phases are located in the final casting, as well as the surface area
ratio of the in situ phase to
the matrix phase, which enables the use of lower cathode phase loadings as
compared to a powder
metallurgical or alloyed composite to achieve the same dissolution rates. The
in situ formed
galvanic additives can be used to enhance mechanical properties of the
magnesium composite such
as ductility, tensile strength, and/or shear strength. The final magnesium
composite can also be
enhanced by heat treatment as well as deformation processing (such as
extrusion, forging, or rolling)
to further improve the strength of the final composite over the as-cast
material; however, this is not
required. The deformation processing can be used to achieve strengthening of
the magnesium
composite by reducing the grain size of the magnesium composite. Further
enhancements, such as
traditional alloy heat treatments (such as solutionizing, aging and/or cold
working) can be used to
enable control of dissolution rates through precipitation of more or less
galvanically-active phases
within the alloy microstructure while improving mechanical properties;
however, this is not
required. Because galvanic corrosion is driven by both the electro potential
between the anode and
cathode phase, as well as the exposed surface area of the two phases, the rate
of corrosion can also
be controlled through adjustment of the in situ formed particle size, while
not increasing or
decreasing the volume or weight fraction of the addition, and/or by changing
the volume/weight
fraction without changing the particle size. Achievement of in situ particle
size control can be
achieved by mechanical agitation of the melt, ultrasonic processing of the
melt, controlling cooling
rates, and/or by performing heat treatments. In situ particle size can also or
alternatively be
modified by secondary processing such as rolling, forging, extrusion and/or
other deformation
techniques.
[0009] In another non-limiting aspect of the invention, a cast structure
can be made into almost
any shape. During formation, the active galvanically-active in situ phases can
be uniformly
dispersed throughout the component and the grain or the grain boundary
composition can be
modified to achieve the desired dissolution rate. The galvanic corrosion can
be engineered to affect
CA 3019702 2018-10-03

only the grain boundaries and/or can affect the grains as well (based on
composition); however, this
is not required. This feature can be used to enable fast dissolutions of high-
strength lightweight
alloy composites with significantly less active (cathode) in situ phases as
compared to other
processes.
[0010] In still another and/or alternative non-limiting aspect of the
invention, ultrasonic
processing can be used to control the size of the in situ formed galvanically-
active phases; however,
this is not required. Ultrasonic energy is used to degass and grain refine
alloys, particularly when
applied in the solidification region. Ultrasonic and stirring can be used to
refine the grain size in
the alloy, thereby creating a high strength alloy and also reducing dispersoid
size and creating more
equiaxed (uniform) grains. Finer grains in the alloy have been found to reduce
the degradation rate
with equal amounts of additives.
[0011] In yet another and/or alternative non-limiting aspect of the
invention, the in situ formed
particles can act as matrix strengtheners to further increase the tensile
strength of the material
compared to the base alloy without the one or more additives; however, this is
not required. For
example, tin can be added to form a nanoscale precipitate (can be heat
treated, e.g., solutionized and
then precipitated to form precipitates inside the primary magnesium grains).
The particles can be
used to increase the strength of the alloy by at least 10%, and as much as
greater than 100%,
depending on other strengthening mechanisms (second phase, grain refinement,
solid solution)
strengthening present.
[0012] In still yet another and/or alternative non-limiting aspect of the
invention, there is
provided a method of controlling the dissolution properties of a metal
selected from the class of
magnesium and/or magnesium alloy comprising of the steps of a) melting the
magnesium or
magnesium alloy to a point above its solidus, b) introducing one or more
additives to the magnesium
or magnesium alloy in order to achieve in situ precipitation of galvanically-
active intermetallic
phases, and c) cooling the melt to a solid form. The one or more additives are
generally added to
the magnesium or magnesium alloy when the magnesium or magnesium alloy is in a
molten state
and at a temperature that is less than the melting point of one or more
additive materials. As can
be appreciated, one or more additives can be added to the molten magnesium or
magnesium alloy
at a temperature that is greater than the melting point of the one or more
additives. The one or
more additives can be added as individual additive elements to the magnesium
or magnesium alloy,
or be added in alloy form as an alloy of two or more additives, or an alloy of
one or more additives
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and magnesium or magnesium alloy. The galvanically-active intermetallic phases
can be used to
enhance the yield strength of the alloy; however, this is not required. The
size of the in situ
precipitated intermetallic phase can be controlled by a melt mixing technique
and/or cooling rate;
however, this is not required. It has been found that the addition of the one
or more additives (SM)
to the molten magnesium or magnesium alloy can result in the formation of
MgSMx, MgxSM, and
LPSO and other phases with two, three, or even four components that include
one or more
galvanically-active additives that result in the controlled degradation of the
formed magnesium
composite when exposed to certain environments (e.g., salt water, brine,
fracking liquids, etc.).
The method can include the additional step of subjecting the magnesium
composite to intermetallic
precipitates to solutionizing of at least about 300 C to improve tensile
strength and/or improve
ductility; however, this is not required. The solutionizing temperature is
less than the melting point
of the magnesium composite. Generally, the solutionizing temperature is less
than 50-200 C of
the melting point of the magnesium composite and the time period of
solutionizing is at least 0.1
hours. In one non-limiting aspect of the invention, the magnesium composite
can be subjected to
a solutionizing temperature for about 0.5-50 hours (and all values and ranges
therebetween) (e.g.,
1-15 hours, etc.) at a temperature of 300-620 C (and all values and ranges
therebetween) (e.g., 300-
500 C, etc.). The method can include the additional step of subjecting the
magnesium composite
to intermetallic precipitates and to artificially age the magnesium composite
at a temperature at least
about 90 C to improve the tensile strength; however, this is not required. The
artificial aging
process temperature is typically less than the solutionizing temperature and
the time period of the
artificial aging process temperature is typically at least 0.1 hours.
Generally, the artificial aging
process at is less than 50-400 C (the solutionizing temperature). In one non-
limiting aspect of the
invention, the magnesium composite can be subjected to the artificial aging
process for about 0.5-
50 hours (and all values and ranges therebetween) (e.g., 1-16 hours, etc.) at
a temperature of 90-
300 C (and all values and ranges therebetween) (e.g., 100-200 C).
[0013]
In still yet another and/or alternative non-limiting aspect of the invention,
there is
provided a magnesium composite that is over 50 wt.% magnesium and about 0.5-
49.5 wt.% of
additive (SM) (e.g., aluminum, zinc, tin, beryllium, boron carbide, copper,
nickel, bismuth, cobalt,
titanium, manganese, potassium, sodium, antimony, indium, strontium, barium,
silicon, lithium,
silver, gold, cesium, gallium, calcium, iron, lead, mercury, arsenic, rare
earth metals (e.g., yttrium,
lanthanum, samarium, europium, gadolinium, terbium, dysprosium, holmium,
ytterbium, etc.) and
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zirconium) (and all values and ranges therebetween) is added to the magnesium
or magnesium alloy
to form a galvanically-active intermetallic particle. The one or more
additives can be added to the
magnesium or magnesium alloy while the temperature of the molten magnesium or
magnesium
alloy is less than or greater than the melting point of the one or more
additives. In one non-limiting
embodiment, throughout the mixing process, the temperature of the molten
magnesium or
magnesium alloy can be less than the melting point of the one or more
additives. In another non-
limiting embodiment, throughout the mixing process, the temperature of the
molten magnesium or
magnesium alloy can be greater than the melting point of the one or more
additives. In another
non-limiting embodiment, throughout the mixing process, the temperature of the
molten magnesium
or magnesium alloy can be greater than the melting point of the one or more
additives and less than
the melting point of one or more other additives. In another non-limiting
embodiment, throughout
the mixing process, the temperature of the molten magnesium or magnesium alloy
can be greater
than the melting point of the alloy that includes one or more additives. In
another non-limiting
embodiment, throughout the mixing process, the temperature of the molten
magnesium or
magnesium alloy can be less than the melting point of the alloy that includes
one or more additives.
During the mixing process, solid particles of SMMgx, SM,Mg can be formed. Once
the mixing
process is complete, the mixture of molten magnesium or magnesium alloy,
SMMgx, SMxMg,
and/or any unalloyed additive is cooled and an in situ precipitate is formed
in the solid magnesium
composite.
[0014]
In another and/or alternative non-limiting aspect of the invention, there is
provided a
magnesium composite that is over 50 wt.% magnesium and about 0.05-49.5 wt.%
nickel (and all
values or ranges therebetween) is added to the magnesium or magnesium alloy to
form intermetallic
Mg2Ni as a galvanically-active in situ precipitate. In one non-limiting
arrangement, the
magnesium composite includes about 0.05-23.5 wt.% nickel, 0.01-5 wt.% nickel,
3-7 wt% nickel,
7-10 wt.% nickel, or 10-24.5 wt.% nickel. The nickel is added to the magnesium
or magnesium
alloy while the temperature of the molten magnesium or magnesium alloy is less
than the melting
point of the nickel; however, this is not required. In one non-limiting
embodiment, throughout the
mixing process, the temperature of the molten magnesium or magnesium alloy is
less than the
melting point of the nickel. During the mixing process, solid particles of
Mg2Ni can be formed;
but is not required. Once the mixing process is complete, the mixture of
molten magnesium or
magnesium alloy, any solid particles of Mg2Ni, and any unalloyed nickel
particles are cooled and
8
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an in situ precipitate of any solid particles of Mg2Ni and any unalloyed
nickel particles is formed in
the solid magnesium composite. Generally, the temperature of the molten
magnesium or
magnesium alloy is at least about 200 C less than the melting point of the
nickel added to the molten
magnesium or magnesium alloy during the addition and mixing process; however,
this is not
required.
[0015] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a magnesium composite that is over 50 wt.% magnesium and about 0.05-49.5 wt.%
copper (and all
values or ranges therebetween) is added to the magnesium or magnesium alloy to
form galvanically-
active in situ precipitate that includes copper and/or copper alloy. In one
non-limiting arrangement,
the magnesium composite includes about 0.01-5 wt.% copper, about 0.5-15 wt.%
copper, about 15-
35 wt.% copper, or about 0.01-20 wt.% copper. The copper is added to the
magnesium or
magnesium alloy while the temperature of the molten magnesium or magnesium
alloy is less than
the melting point of the copper; however, this is not required. In one non-
limiting embodiment,
throughout the mixing process, the temperature of the molten magnesium or
magnesium alloy is
less than the melting point of the copper; however, this is not required.
During the mixing process,
solid particles of CuMg2 can be formed; but is not required. Once the mixing
process is complete,
the mixture of molten magnesium or magnesium alloy, any solid particles of
CuMg2, and any
unalloyed copper particles are cooled and an in situ precipitate of any solid
particles of CuMg2 and
any unalloyed copper particles is formed in the solid magnesium composite.
Generally, the
temperature of the molten magnesium or magnesium alloy is at least about 200 C
less than the
melting point of the copper added to the molten magnesium or magnesium alloy;
however, this is
not required.
[0016] In yet another and/or alternative non-limiting aspect of the
invention, there is provided
a magnesium composite that is over 50 wt.% magnesium and about 0.05-49.5% by
weight cobalt
(and all values and ranges therebetween) is added to the magnesium or
magnesium alloy to form
galvanically active in situ precipitate that includes cobalt and/or cobalt
alloy. In one non-limiting
arrangement, the magnesium composite includes about 0.01-5 wt.% cobalt, about
0.5-15 wt.%
cobalt, about 15-35 wt.% cobalt, or about 0.01-20 wt.% cobalt. The cobalt is
added to the
magnesium or magnesium alloy while the temperature of the molten magnesium or
magnesium
alloy is less than the melting point of the cobalt; however, this is not
required. In one non-limiting
embodiment, throughout the mixing process, the temperature of the molten
magnesium or
9
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magnesium alloy is less than the melting point of the cobalt; however, this is
not required. During
the mixing process, solid particles of CoMg2 and/or MgxCo can be formed; but
is not required.
Once the mixing process is complete, the mixture of molten magnesium or
magnesium alloy, any
solid particles of CoMg2, MgxCo, any solid particles of any unalloyed cobalt
particles are cooled
and an in situ precipitate of any solid particles of CoMg2, MgxCo, any solid
particles of unalloyed
cobalt particles is formed in the solid magnesium composite. Generally, the
temperature of the
molten magnesium or magnesium alloy is at least about 200 C less than the
melting point of the
cobalt added to the molten magnesium or magnesium alloy; however, this is not
required.
[0017] In another and/or alternative non-limiting aspect of the invention,
there is provided a
magnesium composite that is over 50 wt.% magnesium and up to about 49.5% by
weight bismuth
(and all values and ranges therebetween) is added to the magnesium or
magnesium alloy to form
galvanically-active in situ precipitate that includes bismuth and/or bismuth
alloy. Bismuth
intermetallics are formed above roughly 0.1 wt.% bismuth, and bismuth is
typically useful up to its
eutectic point of roughly 11 wt.% bismuth. Beyond the eutectic point, a
bismuth intermetallic is
formed in the melt. This is typical of additions, in that the magnesium-rich
side of the eutectic
forms flowable, castable materials with active precipitates or intermetallics
formed at the solidus
(in the eutectic mixture), rather than being the primary, or initial, phase
solidified. In desirable
alloy formulations, alpha magnesium (may be in solid solution with alloying
elements) should be
the initial/primary phase formed upon initial cooling. In one non-limiting
embodiment, bismuth is
added to the magnesium composite at an amount of greater than 11 wt.%, and
typically about 11.1-
30 wt. % ( and all values and ranges therebetween).
[0018] In another and/or alternative non-limiting aspect of the invention,
there is provided a
magnesium composite that is over 50 wt.% magnesium and up to about 49.5% by
weight tin (and
all values and ranges therebetween) is added to the magnesium or magnesium
alloy to form
galvanically-active in situ precipitate that includes tin and/or tin alloy.
Tin additions have a
significant solubility in solid magnesium at elevated temperatures, forming
both a eutectic (at grain
boundaries), as well as in the primary magnesium (dispersed). Dispersed
precipitates, which can
be controlled by heat treatment, lead to large strengthening, while eutectic
phases are particularly
effective at initiating accelerated corrosion rates. In one non-limiting
embodiment, tin is added to
the magnesium composite at an amount of at least 0.5 wt.%, typically about 1-
30 wt.% ( and all
values and ranges therebetween), and more typically about 1-10 wt.%.
CA 3019702 2018-10-03

[0019] In another and/or alternative non-limiting aspect of the invention,
there is provided a
magnesium composite that is over 50 wt.% magnesium and up to about 49.5% by
weight gallium
(and all values and ranges therebetween) is added to the magnesium or
magnesium alloy to form
galvanically active in situ precipitate that includes gallium and/or gallium
alloy. Gallium additions
are particularly effective at initiating accelerated corrosion, in
concentrations that form up to 3-5
wt.% Mg5Ga2. Gallium alloys are heat treatable forming corrodible high
strength alloys. Gallium
is fairly unique, in that it has high solubility in solid magnesium, and forms
highly corrosive
particles during solidification which are located inside the primary magnesium
(when below the
solid solubility limit), such that both grain boundary and primary
(strengthening precipitates) are
formed in the magnesium-gallium systems and also in magnesium-indium systems.
At gallium
concentrations of less than about 3 wt.%, additional superheat (higher melt
temperatures) is
typically used to form the precipitate in the magnesium alloy. To place Mg5Ga2
particles at the
grain boundaries, gallium concentrations above the solid solubility limit at
the pouring temperature
are used such that Mg5Ga2 phase is formed from the eutectic liquid. In one non-
limiting
embodiment, gallium is added to the magnesium composite at an amount of at
least 1 wt.%, and
typically about 1-10 wt.% ( and all values and ranges therebetween), typically
2-8 wt.%, and more
typically 3.01-5 wt.%.
[0020] In another and/or alternative non-limiting aspect of the invention,
there is provided a
magnesium composite that is over 50 wt.% magnesium and up to about 49.5% by
weight indium
(and all values and ranges therebetween) is added to the magnesium or
magnesium alloy to form
galvanically-active in situ precipitate that includes indium and/or indium
alloy. Indium additions
have also been found effective at initiating corrosion. In one non-limiting
embodiment, indium is
added to the magnesium composite at an amount of at least 1 wt.%, and
typically about 1-30 wt.%
( and all values and ranges therebetween).
[0021] In general, precipitates having an electronegativity greater than
1.4-1.5 act as corrosion
acceleration points, and are more effective if formed from the eutectic liquid
during solidification,
than precipitation from a solid solution. Alloying additions added below their
solid solubility limit
which precipitate in the primary magnesium phase during solidification (as
opposed to along grain
boundaries), and which can be solutionized are more effective in creating
higher strength,
particularly in as-cast alloys.
11
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[0022] In another and/or alternative non-limiting aspect of the invention,
the molten magnesium
or magnesium alloy that includes the one or more additives can be controllably
cooled to form the
in situ precipitate in the solid magnesium composite. In one non-limiting
embodiment, the molten
magnesium or magnesium alloy that includes the one or more additives is cooled
at a rate of greater
than 1 C per minute. In one non-limiting embodiment, the molten magnesium or
magnesium alloy
that includes the one or more additives is cooled at a rate of less than 1 C
per minute. In one non-
limiting embodiment, the molten magnesium or magnesium alloy that includes the
one or more
additives is cooled at a rate of greater than 0.01 C per min and slower than 1
C per minute. In one
non-limiting embodiment, the molten magnesium or magnesium alloy that includes
the one or more
additives is cooled at a rate of greater than 10 C per minute and less than
100 C per minute. In
one non-limiting embodiment, the molten magnesium or magnesium alloy that
includes the one or
more additives is cooled at a rate of less than 10 C per minute. In another
non-limiting
embodiment, the molten magnesium or magnesium alloy that includes the one or
more additives is
cooled at a rate 10-100 C/min (and all values and ranges therebetween) through
the solidus
temperature of the alloy to form fine grains in the alloy.
[0023] In another and/or alternative non-limiting aspect of the invention,
there is provided a
magnesium alloy that includes over 50 wt.% magnesium (e.g., 50.01-99.99 wt.%
and all values and
ranges therebetween) and includes at least one metal selected from the group
consisting of
aluminum, boron, bismuth, zinc, zirconium, and manganese. As can be
appreciated, the
magnesium alloy can include one or more additional metals. In one non-limiting
embodiment, the
magnesium alloy includes over 50 wt.% magnesium and includes at least one
metal selected from
the group consisting of aluminum in an amount of about 0.05-10 wt.% (and all
values and ranges
therebetween), zinc in amount of about 0.05-6 wt.% (and all values and ranges
therebetween),
zirconium in an amount of about 0.01-3 wt.% (and all values and ranges
therebetween), and/or
manganese in an amount of about 0.015-2 wt.% (and all values and ranges
therebetween). In
another non-limiting formulation, the magnesium alloy includes over 50 wt.%
magnesium and
includes at least one metal selected from the group consisting of zinc in
amount of about 0.05-6
wt.%, zirconium in an amount of about 0.05-3 wt.%, manganese in an amount of
about 0.05-0.25
wt.%, boron (optionally) in an amount of about 0.0002-0.04 wt.%, and bismuth
(optionally) in an
amount of about 0.4-0.7 wt.%. In still another and/or alternative non-limiting
aspect of the
invention, there is provided a magnesium alloy that is over 50 wt.% magnesium
and at least one
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metal selected from the group consisting of aluminum in an amount of about
0.05-10 wt.% (and all
values and ranges therebetween), zinc in an amount of about 0.05-6 wt.% (and
all values and ranges
therebetween), calcium in an amount of about 0.5-8 wt.%% (and all values and
ranges
therebetween), zirconium in amount of about 0.05-3 wt.% (and all values and
ranges therebetween),
manganese in an amount of about 0.05-0.25 wt.% (and all values and ranges
therebetween), boron
in an amount of about 0.0002-0.04 wt.% (and all values and ranges
therebetween), and/or bismuth
in an amount of about 0.04-0.7 wt.% (and all values and ranges therebetween).
[0024] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a magnesium composite that is over 50 wt.% magnesium and includes one or more
additives in the
form of a first additive that has an electronegativity that is greater than
1.5, and typically greater
than 1.8. The electronegativity of magnesium is 1.31. As such, the first
additive has a higher
electronegativity than magnesium. The first additive can include one or more
metals selected from
the group consisting of nickel (1.91), cobalt (1.88), copper (1.90), bismuth
(2.02), lead (1.87), tin
(1.96), antimony (2.05), indium (1.78), silver (1.93), gold (2.54), and
gallium (1.81). It has been
found that by adding one or more first additives to a molten magnesium or
molten magnesium alloy,
galvanically-active phases can be formed in the solid magnesium composite
having desired
dissolution rates in salt water, fracking liquid or brine environments. The
one or more first
additives are added to the molten magnesium or molten magnesium alloy such
that the final
magnesium composite includes 0.05-49.55% by weight of the one or more first
additives (and all
values and ranges therebetween), and typically 0.5-35% by weight of the one or
more first additives.
The one or more first additives having an electronegativity that is greater
than 1.5 have been found
to form galvanically-active phases in the solid magnesium composite to enhance
the dissolution rate
of the magnesium composite in salt water, fracking liquid or brine
environments.
[0025] In yet another and/or alternative non-limiting aspect of the
invention, it has been found
that in addition to the adding of one or more first additives having an
electronegativity that is greater
than 1.5 to the molten magnesium or molten magnesium alloy to enhance the
dissolution rates of
the magnesium composite in salt water, fracking liquid or brine environments,
one or more second
additives that have an electronegativity of 1.25 or less can also be added to
the molten magnesium
or molten magnesium alloy to further enhance the dissolution rates of the
solid magnesium
composite. The one or more second additives can optionally be added to the
molten magnesium
or molten magnesium alloy such that the final magnesium composite includes
0.05-35% by weight
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of the one or more second additives (and all values and ranges therebetween),
and typically 0.5-
30% by weight of the one or more second additives. The second additive can
include one or more
metals selected from the group consisting of calcium (1.0), strontium (0.95),
barium (0.89),
potassium (0.82), sodium (0.93), lithium (0.98), cesium (0.79), and the rare
earth metals such as
yttrium (1.22), lanthanum (1.1), samarium (1.17), europium (1.2), gadolinium
(1.2), terbium (1.1),
dysprosium (1.22), holmium (1.23), and ytterbium (1.1).
[0026] Secondary additives are usually added at 0.5-10 wt.%, and generally
0.1-3 wt.%. In
one non-limiting embodiment, the amount of secondary additive is less than the
primary additive;
however, this is not required. For example, calcium can be added up to 10
wt.%, but is added
normally at 0.5-3 wt.%. In most cases, the strengthening alloying additions or
modifying materials
are added in concentrations which can be greater than the high
electronegativity corrosive phase
forming element. The secondary additions are generally designed to have high
solubility, and are
added below their solid solubility limit in magnesium at the melting point,
but above their solid
solubility limit at some lower temperature. These form precipitates that
strengthen the magnesium,
and may or may not be galvanically active. They may form a precipitate by
reacting preferentially
with the high electronegativity addition (e.g., binary, ternary, or even
quaternary intermetallics),
with magnesium, or with other alloying additions.
[0027] The one or more secondary additives that have an electronegativity
that is 1.25 or less
have been found to form galvanically-active phases in the solid magnesium
composite to enhance
the dissolution rate of the magnesium composite in salt water, fracking liquid
or brine environments
are. The inclusion of the one or more second additives with the one or more
first additives in the
molten magnesium or magnesium alloy has been found to enhance the dissolution
rate of the
magnesium composite by 1) alloying with inhibiting aluminum, zinc, magnesium,
alloying
additions and increasing the EMF driving force with the gavanically-active
phase, and/or 2)
reducing the electronegativity of the magnesium (e.g., a-magnesium) phase when
placed in solid
solution or magnesium-EPE (electropositive element) intermetallics. The
addition of materials
with an electronegativity that is less than magnesium, such as rare earths,
group 1, and group II, and
group III elements on the periodic table, can enhance the degradability of the
alloy when a high
electronegativity addition is also present by reducing the electronegativity
(increasing the driving
force) in solid solution in magnesium, and/or by forming lower
electronegativity precipitates that
interact with the higher electronegativity precipitates. This
technique/additions is particularly
14
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effective at reducing the sensitivity of the corrosion rates to temperature or
salt content of the
corroding or downhole fluid.
[0028] The addition of both electropositive (1.5 or greater) first
additives and electronegative
(1.25 or less) second additives to the molten magnesium or magnesium alloy can
result in higher
melting phases being formed in the magnesium composite. These higher melting
phases can create
high melt viscosities and can dramatically increase the temperature (and
therefore the energy input)
required to form the low viscosity melts suitable for casting. By dramatically
increasing the casting
temperature to above 700-780 C, or utilizing pressure to drive mold filling
(e.g., squeeze casting),
such processes can be used to produce a high quality, low-inclusion and low-
porosity magnesium
composite casting.
[0029] In yet another and/or alternative non-limiting aspect of the
invention, there is provided
a magnesium composite that is subjected to heat treatments such as
solutionizing, aging and/or cold
working to be used to control dissolution rates through precipitation of more
or less galvanically-
active phases within the alloy microstructure while improving mechanical
properties. The artificial
aging process (when used) can be for at least about 1 hour, for about 1-50
hours (and all values and
ranges therebetween), for about 1-20 hours, or for about 8-20 hours. The
solutionizing (when used)
can be for at least about 1 hour, for about 1-50 hours (and all values and
ranges therebetween), for
about 1-20 hours, or for about 8-20 hours. When an alloy with a galvanically-
active phase (higher
and/or lower electronegativity than Mg) with significant solid solubility is
solutionized, substantial
differences in corrosion/degradation rates can be achieved through mechanisms
of oswald ripening
or grain growth (coarsening of the active phases), which increases corrosion
rates by 10-100% (and
all values and ranges therebewteen). When the solutionizing removes active
phase and places it in
solid solution, or creates finer precipitates (refined grain sizes), corrosion
rates are decreased by 10-
50%, up to about 75%.
[0030] In still yet another and/or alternative non-limiting aspect of the
invention, there is
provided a method for controlling the dissolution rate of the magnesium
composite wherein the
magnesium content is at least about 75% and at least about 0.05 wt.% nickel is
added to form in situ
precipitation in the magnesium or magnesium alloy and solutionizing the
resultant metal at a
temperature within a range of 100-500 C (and all values and ranges
therebetween) for a period of
0.25-50 hours (and all values and ranges therebetween), the magnesium
composite being
CA 3019702 2018-10-03

characterized by higher dissolution rates than metal without nickel additions
subjected to the said
artificial aging process.
[0031] In another and/or alternative non-limiting aspect of the invention,
there is provided a
method for improving the physical properties of the magnesium composite
wherein the magnesium
content is at least about 85% and at least about 0.05 wt.% nickel is added to
form in situ precipitation
in the magnesium or magnesium alloy and solutionizing the resultant metal at a
temperature at about
100-500 C (and all values and ranges therebetween) for a period of 0.25-50
hours, the magnesium
composite being characterized by higher tensile and yield strengths than
magnesium base alloys of
the same composition, not including the amount of nickel.
[0032] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a method for controlling the dissolution rate of the magnesium composite
wherein the magnesium
content in the alloy is at least about 75% and at least about 0.05 wt.% copper
is added to form in
situ precipitation in the magnesium or magnesium alloy and solutionizing the
resultant metal at a
temperature within a range of 100-500 C for a period of 0.25-50 hours, the
magnesium composite
being characterized by higher dissolution rates than metal without copper
additions subjected to the
said artificial aging process.
[0033] In still yet another and/or alternative non-limiting aspect of the
invention, there is
provided a magnesium composite that includes the addition of calcium to
galvanically-active
magnesium-aluminum-(X) alloys with X being a galvanically-active intermetallic
forming phase
such as, but not limited to, nickel, copper, or cobalt to further control the
degradation rate of the
alloys, further increase the use and extrusion temperature of the magnesium
composite, and/or
reduce the potential for flammability during formation of the magnesium
composite, thereby
increasing safety. Calcium has a higher standard electrode potential than
magnesium at -2.87V as
compared to -2.37V for magnesium relative to standard hydrogen electrode
(SHE). This electrode
potential of calcium makes the galvanic potential between other metallic ions
significantly higher,
such as nickel (-0.25V), copper (+0.52V) and iron (-0.44V). The difference in
galvanic potential
also depends on other alloying elements with respect to microstructural
location. In alloys where
only magnesium and calcium are present, the difference in galvanic potential
can change the
degradation behavior of the alloy by leading to a greater rate of degradation
in the alloy. However,
the mechanism for dissolution speed change in the galvanically-active alloys
created by
intermetallic phases such as magnesium-nickel, magnesium-copper, and magnesium-
cobalt is
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actually different. In the case of the magnesium-aluminum-calcium-(X) with X
being a
galvanically-active intermetallic forming phase such as nickel, copper, or
cobalt with aluminum in
the alloy, the calcium typically bonds with the aluminum (-1.66V), and this
phase precipitates next
to the magnesium matrix. The Mg17A112 phase that is normally precipitated in a
magnesium-
aluminum-(X) with X being a galvanically- active intermetallic forming phase
such as nickel,
copper, or cobalt alloy is the primary contributor to a reduced and controlled
degradation of the
alloy.
[0034]
By introducing calcium into the alloy, the amount of Mg17A112 is reduced in
the alloy,
thus increasing the ratio of magnesium-(X) phase to the pure magnesium alloy
and thereby reducing
the galvanic corrosion resistance of the MgrAl 12 phase, which result in the
further increase of the
degradation rate of the magnesium-aluminum-calcium-(X) alloy as compared to
magnesium-
aluminum-(X) alloys. This feature of the alloy is new and unexpected because
it is not just the
addition of a higher standard electrode potential that is causing the
degradation, but is also the
reduction of a corrosion inhibitor by causing the formation of a different
phase in the alloy. The
calcium addition within the magnesium alloy forms an alternative phase with
aluminum alloying
elements. The calcium bonds with aluminum within the alloy to form lamellar
Al2Ca precipitates
along the grain boundary of the magnesium matrix. These precipitates act as
nucleation sites
during cooling (due to their low energy barrier for nucleation) leading to
decreased grain size and
thereby higher strength for the magnesium alloy. However, the lamellar
precipitates on a
microscopic level tend to shear or cut into the alloy matrix and lead to crack
propagation and can
offset the beneficial strengthening of the grain refinement if an excessive
amount of the Al2Ca phase
is formed. The offsetting grain structure effects typically lead to a minimal
improvement on tensile
strength of the magnesium-aluminum-calcium alloy, if any. This seems to lead
to no significant
reduction in tensile strength of the alloy. The significant advantage for the
addition of calcium in
a magnesium-aluminum alloy is in the improved incipient melting temperature
when the Al2Ca
phase is formed as opposed to Mgi7A112. Al2Ca has a melting temperature of
approximately
1080 C as opposed to 460 C for the magnesium-aluminum phase, which means a
higher incipient
melting point for the alloy. This solution leads to a larger hot deformation
processing window or,
more specifically, greater speeds during extrusion or rolling. These greater
speeds can lead to
lower cost production and a safer overall product. Another benefit of the
calcium addition into the
alloy is reduced oxidation of the melt. This feature is a result of the CaO
layer which forms on the
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surface of the melt. In melt protection, the thickness and density of the
calcium layer benefits the
melt through formation of a reinforced CaO-MgO oxide layer when no other
elements are present.
This layer reduces the potential for "burning" in the foundry, thus allows for
higher casting
temperatures, reduced cover gas, reduced flux use and improved safety and
throughput. The oxide
layer also significantly increases the ignition temperature by eliminating the
magnesium oxide layer
typically found on the surface and replacing it with the much more stable CaO.
The calcium
addition in the magnesium alloy is generally at least 0.05 wt.% and generally
up to about 30 wt.%
(and all values and ranges therebetween), and typically 0.1-15 wt.%.
[0035] The developed alloys can be degraded in solutions with salt contents
as low as 0.01% at
a rate of 1-100mg/cm2-hr. (and all values and ranges therebetween) at a
temperature of 20-100 C
(and all values and ranges therebetween). The calcium additions work to
enhance degradation in
this alloy system, not by traditional means of adding a higher standard
electrode potential material
as would be common practice, but by actually reducing the corrosion inhibiting
phase of Mgi7A112
by the precipitation of Al2Ca phases that are mechanically just as strong, but
do not inhibit the
corrosion. As such, alloys can be created with higher corrosion rates just as
alloys can be created
by reducing aluminum content, but without strength degradation and the added
benefit of higher
use temperature, higher incipient melting temperatures and/or lower
flammability. The alloy is a
candidate for use in all degradation applications such as downhole tools,
temporary structures, etc.
where strength and high use temperature are a necessity and it is desirable to
have a greater rate of
dissolving or degradation rates in low-salt concentration solutions.
[0036] In yet another and/or alternative non-limiting aspect of the
invention, there is provided
a method for improving the physical properties of the magnesium composite
wherein the total
content of magnesium in the magnesium or magnesium alloy is at least about 85
wt.% and copper
is added to form in situ precipitation in the magnesium or magnesium composite
and solutionizing
the resultant metal at a temperature of about 100-500 C for a period of 0.25-
50 hours. The
magnesium composite is characterized by higher tensile and yield strengths
than magnesium-based
alloys of the same composition, but not including the amount of copper.
[0037] In still yet another and/or alternative non-limiting aspect of the
invention, there is
provided a magnesium composite for use as a dissolvable ball or frac ball in
hydraulic fracturing
and well drilling.
18
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[0038] In another and/or alternative non-limiting aspect of the invention,
there is provided a
magnesium composite for use as a dissolvable tool for use in well drilling and
hydraulic control as
well as hydraulic fracturing.
[0039] In another and/or alternative non-limiting aspect of the invention,
there is provided a
magnesium composite that has controlled dissolution or degradation for use in
temporarily isolating
a wellbore.
[0040] In another and/or alternative non-limiting aspect of the invention,
there is provided a
magnesium composite that can be used to partially or full form a mandrel,
slip, grip, ball, frac ball,
dart, sleeve, carrier, or other downhole well component.
[0041] In another and/or alternative non-limiting aspect of the invention,
there is provided a
magnesium composite that can be used for controlling fluid flow or mechanical
activation of a
downhole device.
[0042] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a magnesium composite that includes secondary in situ formed reinforcements
that are not
galvanically active to the magnesium or magnesium alloy matrix to increase the
mechanical
properties of the magnesium composite. The secondary in situ formed
reinforcements can optionally
include a Mg2Si phase as the in situ formed reinforcement.
[0043] In yet another and/or alternative non-limiting aspect of the
invention, there is provided
a magnesium composite that is subjected to a greater rate of cooling from the
liquidus to the solidus
point to create smaller in situ formed particles.
[0044] In still yet another and/or alternative non-limiting aspect of the
invention, there is
provided a magnesium composite that is subjected to a slower rate of cooling
from the liquidus to
the solidus point to create larger in situ formed particles.
[0045] In yet another and/or alternative non-limiting aspect of the
invention, there is provided
a magnesium composite that is subjected to heat treatments such as
solutionizing, aging and/or cold
working to be used to control dissolution rates though precipitation of more
or less galvanically-
active phases within the alloy microstructure while improving mechanical
properties. The artificial
aging process (when used) can be for at least about 1 hour, for about 1-50
hours, for about 1-20
hours, or for about 8-20 hours. The solutionizing (when used) can be for at
least about 1 hour, for
about 1-50 hours, for about 1-20 hours, or for about 8-20 hours.
19
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[0046] In still yet another and/or alternative non-limiting aspect of the
invention, there is
provided a method for controlling the dissolution rate of the magnesium
composite wherein the
magnesium content is at least about 75 wt.% and at least 0.05 wt.% nickel is
added to form in situ
precipitation in the magnesium or magnesium alloy and solutionizing the
resultant metal at a
temperature within a range of 100-500 C for a period of 0.25-50 hours, the
magnesium composite
being characterized by higher dissolution rates than metal without nickel
additions subjected to the
said artificial aging process.
[0047] In another and/or alternative non-limiting aspect of the invention,
there is provided a
method for improving the physical properties of the magnesium composite
wherein the magnesium
content is at least about 85 wt.% and at least 0.05 wt.% nickel is added to
form in situ precipitation
in the magnesium or magnesium alloy and solutionizing the resultant metal at a
temperature at about
100-500 C for a period of 0.25-50 hours, the magnesium composite being
characterized by higher
tensile and yield strengths than magnesium base alloys of the same
composition, but not including
the amount of nickel.
[0048] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a method for controlling the dissolution rate of the magnesium composite
wherein the magnesium
content in the alloy is at least about 75 wt.% and at least 0.05 wt.% copper
is added to form in situ
precipitation in the magnesium or magnesium alloy and solutionizing the
resultant metal at a
temperature within a range of 100-500 C for a period of 0.25-50 hours, the
magnesium composite
being characterized by higher dissolution rates than metal without copper
additions subjected to the
said artificial aging process.
[0049] In yet another and/or alternative non-limiting aspect of the
invention, there is provided
a method for improving the physical properties of the magnesium composite
wherein the total
content of magnesium in the magnesium or magnesium alloy is at least about 85
wt.% and at least
0.05 wt.% copper is added to form in situ precipitation in the magnesium or
magnesium composite
and solutionizing the resultant metal at a temperature of about 100-500 C for
a period of 0.25-50
hours, the magnesium composite being characterized by higher tensile and yield
strengths than
magnesium base alloys of the same composition, but not including the amount of
copper.
[0050] In still another and/or alternative non-limiting aspect of the
invention, the additive
generally has a solubility in the molten magnesium or magnesium alloy of less
than about 10% (e.g.,
CA 3019702 2018-10-03

0.01-9.99% and all values and ranges therebetween), typically less than about
5%, more typically
less than about 1%, and even more typically less than about 0.5%.
[0051] In still another and/or alternative non-limiting aspect of the
invention, the additive can
optionally have a surface area of 0.001-200m2/g (and all values and ranges
therebetween). The
additive in the magnesium composite can optionally be less than about 1 pn in
size (e.g., 0.001-
0.999 lam and all values and ranges therebetween), typically less than about
0.5 flm, more typically
less than about 0.1 [tm, and more typically less than about 0.05 Jim. The
additive can optionally
be dispersed throughout the molten magnesium or magnesium alloy using
ultrasonic means,
electrowetting of the insoluble particles, and/or mechanical agitation. In one
non-limiting
embodiment, the molten magnesium or magnesium alloy is subjected to ultrasonic
vibration and/or
waves to facilitate in the dispersion of the additive in the molten magnesium
or magnesium alloy.
[0052] In still yet another and/or alternative non-limiting aspect of the
invention, a plurality of
additives in the magnesium composite are located in grain boundary layers of
the magnesium
composite.
[0053] In still yet another and/or alternative non-limiting aspect of the
invention, there is
provided a method for forming a magnesium composite that includes a) providing
magnesium or a
magnesium alloy, b) providing one or more additives that have a low solubility
when added to
magnesium or a magnesium alloy when in a molten state; c) mixing the magnesium
or a magnesium
alloy and the one or more additives to form a mixture and to cause the one or
more additives to
disperse in the mixture; and d) cooling the mixture to form the magnesium
composite. The step of
mixing optionally includes mixing using one or more processes selected from
the group consisting
of thixomolding, stir casting, mechanical agitation, electrowetting and
ultrasonic dispersion. The
method optionally includes the step of heat treating the magnesium composite
to improve the tensile
strength, elongation, or combinations thereof of the magnesium composite
without significantly
affecting a dissolution rate of the magnesium composite. The method optionally
includes the step
of extruding or deforming the magnesium composite to improve the tensile
strength, elongation, or
combinations thereof of the magnesium composite without significantly
affecting a dissolution rate
of the magnesium composite. The method optionally includes the step of forming
the magnesium
composite into a device that a) facilitates in separating hydraulic fracturing
systems and zones for
oil and gas drilling, b) provides structural support or component isolation in
oil and gas drilling and
completion systems, or c) is in the form of a frac ball, valve, or degradable
component of a well
21
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composition tool or other tool. Other types of structures that the magnesium
composite can be
partially or fully formed into include, but are not limited to, sleeves,
valves, hydraulic actuating
tooling and the like. Such non-limiting structures or additional non-limiting
structure are
illustrated in US Patent Nos. 8,905,147; 8,717,268; 8,663,401; 8,631,876;
8,573,295; 8,528,633;
8,485,265; 8,403,037; 8,413,727; 8,211,331; 7,647,964; US Publication Nos.
2013/0199800;
2013/0032357; 2013/0029886; 2007/0181224; and WO 2013/122712.
[0054] In still yet another and/or alternative non-limiting aspect of the
invention, there is
provided a magnesium composite for use as a dissolvable ball or frac ball in
hydraulic fracturing
and well drilling.
[0055] In another and/or alternative non-limiting aspect of the invention,
there is provided a
magnesium composite for use as a dissolvable tool for use in well drilling and
hydraulic control as
well as hydraulic fracturing.
[0056] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a magnesium composite that includes secondary in situ formed reinforcements
that are not
galvanically active to the magnesium or magnesium alloy matrix to increase the
mechanical
properties of the magnesium composite. The secondary in situ formed
reinforcements include a
Mg2Si phase or silicon particle phase as the in situ formed reinforcement.
[0057] In yet another and/or alternative non-limiting aspect of the
invention, there is provided
a magnesium composite that is subjected to a greater rate of cooling from the
liquidus to the solidus
point to create smaller in situ formed particles.
[0058] In still yet another and/or alternative non-limiting aspect of the
invention, there is
provided a magnesium composite that is subjected to a slower cooling rate from
the liquidus to the
solidus point to create larger in situ formed particles.
[0059] In yet another and/or alternative non-limiting aspect of the
invention, there is provided
a magnesium composite that is subjected to heat treatments such as
solutionizing, aging and/or cold
working to be used to control dissolution rates through precipitation of more
or less galvanically-
active phases within the alloy microstructure while improving mechanical
properties. The artificial
aging process (when used) can be for at least about 1 hour, for about 1-50
hours (and all values and
ranges therebetween), for about 1-20 hours, or for about 8-20 hours.
Solutionizing (when used)
can be for at least about 1 hour, for about 1-50 hours (and all values and
ranges therebetween), for
about 1-20 hours, or for about 8-20 hours.
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[0060] In another and/or alternative non-limiting aspect of the invention,
there is provided a
magnesium composite that is subjected to mechanical agitation during the
cooling rate from the
liquidus to the solidus point to create smaller in situ formed particles.
[0061] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a magnesium composite that is subjected to chemical agitation during the
cooling rate from the
liquidus to the solidus point to create smaller in situ formed particles.
[0062] In yet another and/or alternative non-limiting aspect of the
invention, there is provided
a magnesium composite that is subjected to ultrasonic agitation during the
cooling rate from the
liquidus to the solidus point to create smaller in situ formed particles.
[0063] In still yet another and/or alternative non-limiting aspect of the
invention, there is
provided a magnesium composite that is subjected to deformation or extrusion
to further improve
dispersion of the in situ formed particles.
[0064] In still yet another and/or alternative non-limiting aspect of the
invention, there is
provided a magnesium composite that has a dissolve rate or dissolution rate of
at least about 30
mg/cm2-hr in 3% KC1 solution at 90 C, and typically 30-500 mg/cm2-hr in 3% KCl
solution at 90 C
(and all values and ranges therebetween).
[0065] In still yet another and/or alternative non-limiting aspect of the
invention, there is
provided a magnesium composite that has a dissolve rate or dissolution rate of
at least about 0.2
mg/cm2-min in a 3% KCI solution at 90 C, and typically 0.2-150 mg/cm2-min in a
3% KCl solution
at 90 C (and all values and ranges therebetween).
[0066] In still yet another and/or alternative non-limiting aspect of the
invention, there is
provided a magnesium composite that has a dissolve rate or dissolution rate of
at least about 0.1
mg/cm2-hr in a 3% KC1 solution at 21 C, and typically 0.1-5 mg/cm2-hr in a 3%
KC1 solution at
21 C (and all values and ranges therebetween).
[0067] In still yet another and/or alternative non-limiting aspect of the
invention, there is
provided a magnesium composite that has a dissolve rate or dissolution rate of
at least about
0.2mg/cm2-min in a 3% KC1 solution at 20 C.
[0068] In still yet another and/or alternative non-limiting aspect of the
invention, there is
provided a magnesium composite that has a dissolve rate or dissolution rate of
at least about 0.1
mg/cm2-hr in 3% KC1 solution at 20 C, typically 0.1-5 mg/cm2-hr in a 3% KC1
solution at 20 C
(and all values and ranges therebetween).
23
CA 3019702 2018-10-03

[0069] In another and/or alternative non-limiting aspect of the invention,
there is provided a
method for forming a novel magnesium composite including the steps of a)
selecting an AZ91D
magnesium alloy having 9 wt.% aluminum, 1 wt.% zinc and 90 wt.% magnesium, b)
melting the
AZ91 D magnesium alloy to a temperature above 800 C, c) adding up to about 7
wt.% nickel to the
melted AZ91D magnesium alloy at a temperature that is less than the melting
point of nickel, d)
mixing the nickel with the melted AZ91D magnesium alloy and dispersing the
nickel in the melted
alloy using chemical mixing agents while maintaining the temperature below the
melting point of
nickel, and e) cooling and casting the melted mixture in a steel mold. The
cast material has a tensile
strength of about 14 ksi, and an elongation of about 3% and a shear strength
of 11 ksi. The cast
material has a dissolve rate of about 75 mg/cm2-min in a 3% KC1 solution at 90
C. The cast
material dissolves at a rate of 1 mg/cm2-hr in a 3% KC1 solution at 21 C. The
cast material
dissolves at a rate of 325 mg/cm2-hr. in a 3% KCl solution at 90 C. The cast
material can be
subjected to extrusion with an 11:1 reduction area. The extruded cast material
exhibits a tensile
strength of 40 ksi, and an elongation to failure of 12%. The extruded cast
material dissolves at a
rate of 0.8 mg/cm2-min in a 3% KC1 solution at 20 C. The extruded cast
material dissolves at a
rate of 100 mg/cm2-hr. in a 3% KCI solution at 90 C. The extruded cast
material can be subjected
to an artificial T5 age treatment of 16 hours between 100-200 C. The aged and
extruded cast
material exhibits a tensile strength of 48 ksi, an elongation to failure of
5%, and a shear strength of
25 ksi. The aged extruded cast material dissolves at a rate of 110 mg/cm2-hr
in 3% KCl solution
at 90 C and 1 mg/cm2-hr in 3% KC1 solution at 20 C. The cast material can be
subjected to a
solutionizing treatment T4 for about 18 hours between 400-500 C and then
subjected to an artificial
T6 age treatment for about 16 hours between 100-200 C. The aged and
solutionized cast material
exhibits a tensile strength of about 34 ksi, an elongation to failure of about
11 %, and a shear strength
of about 18 ksi. The aged and solutionized cast material dissolves at a rate
of about 84mg/cm2-hr
in 3% KCl solution at 90 C, and about 0.8 mg/cm2-hr in 3% KC1 solution at 20
C.
[0070] In another and/or alternative non-limiting aspect of the invention,
there is provided a
method for forming a novel magnesium composite including the steps of a)
selecting an AZ91D
magnesium alloy having 9 wt.% aluminum, 1 wt.% zinc and 90 wt.% magnesium, b)
melting the
AZ91D magnesium alloy to a temperature above 800 C, c) adding up to about 1
wt.% nickel to the
melted AZ91D magnesium alloy at a temperature that is less than the melting
point of nickel, d)
mixing the nickel with the melted AZ91D magnesium alloy and dispersing the
nickel in the melted
24
CA 3019702 2018-10-03

alloy using chemical mixing agents while maintaining the temperature below the
melting point of
nickel, and e) cooling and casting the melted mixture in a steel mold. The
cast material has a tensile
strength of about 18 ksi, and an elongation of about 5% and a shear strength
of 17ksi. The cast
material has a dissolve rate of about 45 mg/cm2-min in a 3% KC1 solution at 90
C. The cast
material dissolves at a rate of 0.5 mg/cm2-hr. in a 3% KCI solution at 21 C.
The cast material
dissolves at a rate of 325 mg/cm2-hr. in a 3% KC1 solution at 90 C. The cast
material is subjected
to extrusion with a 20:1 reduction area. The extruded cast material exhibits a
tensile yield strength
of 35 ksi, and an elongation to failure of 12%. The extruded cast material
dissolves at a rate of 0.8
mg/cm2-min in a 3% KCl solution at 20 C. The extruded cast material dissolves
at a rate of 50
mg/cm2-hr in a 3% KC1 solution at 90 C. The extruded cast material can be
subjected to an
artificial T5 age treatment of 16 hours between 100-200 C. The aged and
extruded cast material
exhibits a tensile strength of 48 ksi, an elongation to failure of 5%, and a
shear strength of 25 ksi.
[0071] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a method for forming a novel magnesium composite including the steps of a)
selecting an AZ9ID
magnesium alloy having about 9 wt.% aluminum, 1 wt.% zinc and 90 wt.%
magnesium, b) melting
the AZ9ID magnesium alloy to a temperature above 800 C, c) adding about 10
wt.% copper to the
melted AZ9ID magnesium alloy at a temperature that is less than the melting
point of copper, d)
dispersing the copper in the melted AZ9ID magnesium alloy using chemical
mixing agents at a
temperature that is less than the melting point of copper, and e) cooling
casting the melted mixture
in a steel mold. The cast material exhibits a tensile strength of about 14
ksi, an elongation of about
3%, and shear strength of 11 ksi. The cast material dissolves at a rate of
about 50 mg/cm2-hr. in a
3% KC1 solution at 90 C. The cast material dissolves at a rate of 0.6 mg/cm2-
hr. in a 3% KC1
solution at 21 C. The cast material can be subjected to an artificial T5 age
treatment for about 16
hours at a temperature of 100-200 C. The aged cast material exhibits a tensile
strength of 50 ksi,
an elongation to failure of 5%, and a shear strength of 25 ksi. The aged cast
material dissolved at
a rate of 40mg/cm2-hr in 3% KC1 solution at 90 C and 0.5 mg/cm2-hr in 3% KC1
solution at 20 C.
[0072] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a method for forming a novel magnesium composite including the steps of a)
providing magnesium
having a purity of at least 99.9%, b) providing antimony having a purity of at
least 99.8%, c) adding
the magnesium and antimony in the crucible (e.g., carbon steel crucible), d)
optionally adding a flux
to the top of the metals in the crucible, e) optionally heating the metals in
the crucible to 250 C for
CA 3019702 2018-10-03

about 2-60 minutes, 0 heating the metals in the crucible to 650-720 C to cause
the magnesium to
melt, and g) cooling the molten magnesium to form a magnesium composite that
includes about 7
wt.% antimony. The density of the magnesium composite is 1.69 g/cm3, the
hardness is 6.8
Rockwell Hardness B, and the dissolution rate in 3% solution of KC1 at 90 C is
20.09 mg/cm2-hr.
[0073] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a method for forming a novel magnesium composite including the steps of a)
providing magnesium
having a purity of at least 99.9%, b) providing gallium having a purity of at
least 99.9%, c) adding
the magnesium and gallium in the crucible (e.g., carbon steel crucible), d)
optionally adding a flux
to the top of the metals in the crucible, e) optionally heating the metals in
the crucible to 250 C for
about 2-60 minutes, 0 heating the metals in the crucible to 650-720 C to cause
the magnesium to
melt, and g) cooling the molten magnesium to form a magnesium composite that
includes about 5
wt.% gallium. The density of the magnesium composite is 1.80 g/cm3, the
hardness is 67.8
Rockwell Hardness B, and the dissolution rate in 3% solution of KC1 at 90 C is
0.93 mg/cm2-hr.
[0074] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a method for forming a novel magnesium composite including the steps of a)
providing magnesium
having a purity of at least 99.9%, b) providing tin having a purity of at
least 99.9%, c) adding the
magnesium and tin in the crucible (e.g., carbon steel crucible), d) optionally
adding a flux to the top
of the metals in the crucible, e) optionally heating the metals in the
crucible to 250 C for about 2-
60 minutes, 0 heating the metals in the crucible to 650-720 C to cause the
magnesium to melt, and
g) cooling the molten magnesium to form a magnesium composite that includes
about 13 wt.% tin.
The density of the magnesium composite is 1.94 g/cm3, the hardness is 75.6
Rockwell Hardness B,
and the dissolution rate in 3% solution of KCI at 90 C is 0.02 mg/cm2-hr.
[0075] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a method for forming a novel magnesium composite including the steps of a)
providing magnesium
having a purity of at least 99.9%, b) providing bismuth having a purity of at
least 99.9%, c) adding
the magnesium and bismuth in the crucible (e.g., carbon steel crucible), d)
optionally adding a flux
to the top of the metals in the crucible, e) optionally heating the metals in
the crucible to 250 C for
about 2-60 minutes, 0 heating the metals in the crucible to 650-720 C to cause
the magnesium to
melt, and g) cooling the molten magnesium to form a magnesium composite that
includes about 10
wt.% bismuth. The density of the magnesium composite is 1.86 g/cm3, the
hardness is 16.9
Rockwell Hardness B, and the dissolution rate in 3% solution of KCl at 90 C is
26.51 mg/cm2-hr.
26
CA 3019702 2018-10-03

[0076]
In still another and/or alternative non-limiting aspect of the invention,
there is provided
a method for controlling the dissolution properties of a magnesium or a
magnesium alloy comprising
of the steps of: a) heating the magnesium or a magnesium alloy to a point
above its solidus
temperature; b) adding an additive to said magnesium or magnesium alloy while
said magnesium
or magnesium alloy is above said solidus temperature of magnesium or magnesium
alloy to form a
mixture, said additive including one or more first additives having an
electronegativity of greater
than 1.5, said additive constituting about 0.05-45 wt.% of said mixture; c)
dispersing said additive
in said mixture while said magnesium or magnesium alloy is above said solidus
temperature of
magnesium or magnesium alloy; and, d) cooling said mixture to form a magnesium
composite, said
magnesium composite including in situ precipitation of galvanically-active
intermetallic phases.
The first additive can optionally have an electronegativity of greater than
1.8. The step of
controlling a size of said in situ precipitated intermetallic phase can
optionally be by controlled
selection of a mixing technique during said dispersion step, controlling a
cooling rate of said
mixture, or combinations thereof. The magnesium or magnesium alloy can
optionally be heated to
a temperature that is less than said melting point temperature of at least one
of said additives. The
magnesium or magnesium alloy can be heated to a temperature that is greater
than said melting
point temperature of at least one of said additives. The additive can
optionally include one or
more metals selected from the group consisting of calcium, copper, nickel,
cobalt, bismuth, silver,
gold, lead, tin, antimony, indium, arsenic, mercury, and gallium. The additive
can optionally
include one or more metals selected from the group consisting of calcium,
copper, nickel, cobalt,
bismuth, tin, antimony, indium, and gallium. The additive can optionally
include one or more
second additives that have an electronegativity of less than 1.25. The second
additive can
optionally include one or more metals selected from the group consisting of
strontium, barium,
potassium, sodium, lithium, cesium, and the rare earth metals such as yttrium,
lanthanum,
samarium, europium, gadolinium, terbium, dysprosium, holmium, and ytterbium.
The additive can
optionally be formed of a single composition, and has an average particle
diameter size of about
0.1-500 microns. At least a portion of said additive can optionally remain at
least partially in
solution in an a-magnesium phase of said magnesium composite. The magnesium
alloy can
optionally include over 50 wt.% magnesium and one or more metals selected from
the group
consisting of aluminum, boron, bismuth, zinc, zirconium, and manganese. The
magnesium alloy
can optionally include over 50 wt.% magnesium and one or more metals selected
from the group
27
CA 3019702 2018-10-03

consisting of aluminum in an amount of about 0.5-10 wt.%, zinc in amount of
about 0.1-6 wt.%,
zirconium in an amount of about 0.01-3 wt.%, manganese in an amount of about
0.15-2 wt.%; boron
in amount of about 0.0002-0.04 wt.%, and bismuth in amount of about 0.4-0.7
wt.%. The
magnesium alloy can optionally include over 50 wt.% magnesium and one or more
metals selected
from the group consisting of aluminum in an amount of about 0.5-10 wt.%, zinc
in amount of about
0.1-3 wt.%, zirconium in an amount of about 0.01-1 wt.%, manganese in an
amount of about 0.15-
2 wt.%; boron in amount of about 0.0002-0.04 wt.%, and bismuth in amount of
about 0.4-0.7.wt %.
The step of solutionizing said magnesium composite can optionally occur at a
temperature above
300 C and below a melting temperature of said magnesium composite to improve
tensile strength,
ductility, or combinations thereof of said magnesium composite. The step of
forming said
magnesium composite into a final shape or near net shape can optionally be by
a) sand casting,
permanent mold casting, investment casting, shell molding, or other
pressureless casting technique
at a temperature above 730 C, 2) using either pressure addition or elevated
pouring temperatures
above 710 C, or 3) subjecting the magnesium composite to pressures of 2000-
20,000 psi through
the use of squeeze casting, thixomolding, or high pressure die casting
techniques. The step of aging
said magnesium composite can optionally be at a temperature of above 100 C and
below 300 C to
improve tensile strength of said magnesium composite.
The magnesium composite can
optionally have a hardness above 14 Rockwell Harness B. The magnesium
composite can
optionally have a dissolution rate of at least 5 mg/cm2-hr. in 3% KCl at 90 C.
The additive metal
can optionally include about 0.05-35 wt.% nickel. The additive can optionally
include about 0.05-
35 wt.% copper. The additive can optionally include about 0.05-35 wt.%
antimony. The additive
can optionally include about 0.05-35 wt.% gallium. The additive can optionally
include about
0.05-35 wt.% tin. The additive can optionally include about 0.05-35 wt.%
bismuth. The additive
can optionally include about 0.05-35 wt.% calcium. The method can optionally
further include the
step of rapidly solidifying said magnesium composite by atomizing the molten
mixture and then
subjecting the atomized molten mixture to ribbon casting, gas and water
atomization, pouring into
a liquid, high speed machining, saw cutting, or grinding into chips, followed
by powder or chip
consolidation below its liquidus temperature.
[0077]
In still another and/or alternative non-limiting aspect of the invention,
there is provided
a magnesium composite that includes in situ precipitation of galvanically-
active intermetallic phases
comprising a magnesium or a magnesium alloy and an additive constituting about
0.05-45 wt.% of
28
CA 3019702 2018-10-03

said magnesium composite, said magnesium having a content in said magnesium
composite that is
greater than 50 wt.%, said additive forming metal composite particles or
precipitant in said
magnesium composite, said metal composite particles or precipitant forming
said in situ
precipitation of said galvanically-active intermetallic phases, said additive
including one or more
first additives having an electronegativity of greater than 1.5. The magnesium
composite can
optionally further include one or more second additives having an
electronegativity of less than
1.25. The first additive can optionally have an electronegativity of greater
than 1.8. The first
additive can optionally include one or more metals selected from the group
consisting of copper,
nickel, cobalt, bismuth, silver, gold, lead, tin, antimony, indium, arsenic,
mercury, and gallium.
The first additive can optionally include one or more metals selected from the
group consisting of
copper, nickel, cobalt, bismuth, tin, antimony, indium, and gallium. The
second additive can
optionally include one or more metals selected from the group consisting of
calcium, strontium,
barium, potassium, sodium, lithium, cesium, and the rare earth metals such as
yttrium, lanthanum,
samarium, europium, gadolinium, terbium, dysprosium, holmium, and ytterbium.
The magnesium
alloy can optionally include over 50 wt.% magnesium and one or more metals
selected from the
group consisting of aluminum, boron, bismuth, zinc, zirconium, and manganese.
The magnesium
alloy can optionally include over 50 wt.% magnesium and one or more metals
selected from the
group consisting of aluminum in an amount of about 0.5-10 wt.%, zinc in amount
of about 0.1-3
wt.%, zirconium in an amount of about 0.01-1 wt.%, manganese in an amount of
about 0.15-2 wt.%,
boron in amount of about 0.0002-0.04 wt.%, and bismuth in amount of about 0.4-
0.7 wt.%. The
additive can optionally include about 0.05-45 wt.% nickel. The first additive
can optionally
include about 0.05-45 wt.% copper. The first additive can optionally include
about 0.05-45 wt.%
cobalt. The first additive can optionally include about 0.05-45 wt.% antimony.
The first additive
can optionally include about 0.05-45 wt.% gallium. The first additive can
optionally include about
0.05-45 wt.% tin. The first additive can optionally include about 0.05-45 wt.%
bismuth. The
second additive can optionally include 0.05-35 wt.% calcium. The magnesium
composite can
optionally have a hardness above 14 Rockwell Harness B. The magnesium
composite can
optionally have a dissolution rate of at least 5 mg/cm2-hr. in 3% KCl at 90 C.
The magnesium
composite can optionally have a dissolution rate of about 5-300 mg/cm2-hr in 3
wt.% KC1 water
mixture at 90 C. The magnesium composite can optionally be subjected to a
surface treatment to
improve a surface hardness of said magnesium composite, said surface treatment
including peening,
29
CA 3019702 2018-10-03

heat treatment, aluminizing, or combinations thereof A dissolution rate of
said magnesium
composite can optionally be controlled by an amount and size of said in situ
formed galvanically-
active particles whereby smaller average sized particles of said in situ
formed galvanically-active
particles, a greater weight percent of said in situ formed galvanically-active
particles in said
magnesium composite, or combinations thereof increases said dissolution rate
of said magnesium
composite.
[0078]
In still another and/or alternative non-limiting aspect of the invention,
there is provided
a dissolvable component for use in downhole operations that is fully or
partially formed of a
magnesium composite, said dissolvable component including a component selected
from the group
consisting of sleeve, frac ball, hydraulic actuating tooling, mandrel, slip,
grip, ball, dart, carrier,
tube, valve, valve component, plug, or other downhole well component, said
magnesium composite
includes in situ precipitation of galvanically-active intermetallic phases
comprising a magnesium
or a magnesium alloy and an additive constituting about 0.05-45 wt.% of said
magnesium
composite, said magnesium having a content in said magnesium composite that is
greater than 50
wt.%, said additive forming metal composite particles or precipitant in said
magnesium composite,
said metal composite particles or precipitant forming said in situ
precipitation of said galvanically-
active intermetallic phases, said additive including one or more first
additives having an
electronegativity of greater than 1.5. The dissolvable component can
optionally further include
one or more second additives having an electronegativity of less than 1.25.
The first additive can
optionally have an electronegativity of greater than 1.8. The first additive
can optionally include
one or more metals selected from the group consisting of copper, nickel,
cobalt, bismuth, silver,
gold, lead, tin, antimony, indium, arsenic, mercury, and gallium. The first
additive can optionally
include one or more metals selected from the group consisting of copper,
nickel, cobalt, bismuth,
tin, antimony, indium, and gallium. The second additive can optionally include
one or more metals
selected from the group consisting of calcium, strontium, barium, potassium,
sodium, lithium,
cesium, and the rare earth metals such as yttrium, lanthanum, samarium,
europium, gadolinium,
terbium, dysprosium, holmium, and ytterbium. The second additive can
optionally include 0.05-
35 wt.% calcium. The magnesium alloy can optionally include over 50 wt.%
magnesium and one
or more metals selected from the group consisting of aluminum, boron, bismuth,
zinc, zirconium,
and manganese. The magnesium composite can optionally have a hardness above 14
Rockwell
Harness B. The magnesium composite can optionally have a dissolution rate of
at least 5 mg/cm2-
CA 3019702 2018-10-03

hr. in 3% KC1 at 90 C. The magnesium composite can optionally have a
dissolution rate of at least
mg/cm2-hr in a 3% KC1 solution at 90 C. The magnesium composite can optionally
have a
dissolution rate of at least 20 mg/cm2-hr in a 3% KC1 solution at 65 C. The
magnesium composite
can optionally have a dissolution rate of at least 1 mg/cm2-hr in a 3% KCl
solution at 65 C. The
magnesium composite can optionally have a dissolution rate of at least 100
mg/cm2-hr in a 3% KC1
solution at 90 C. The magnesium composite can optionally have a dissolution
rate of at least 45
mg/cm2/hr. in 3 wt.% KCl water mixture at 90 C and up to 325 mg/cm2/hr. in 3
wt.% KC1 water
mixture at 90 C. The magnesium composite can optionally have a dissolution
rate of up to 1
mg/cm2/hr. in 3 wt.% KCl water mixture at 21 C. The magnesium composite can
optionally have
a dissolution rate of at least 90 mg/cm2-hr. in 3% KC1 solution at 90 C. The
magnesium composite
can optionally have a dissolution rate of at least a rate of 0.1 mg/cm2-hr. in
0.1% KCl solution at
90 C. The magnesium composite can optionally have a dissolution rate of a rate
of <0.1 mg/cm2-
hr. in 0.1% KCl solution at 75 C. The magnesium composite can optionally have
a dissolution rate
of, a rate of <0.1 mg/cm2-hr. in 0.1% KCl solution at 60 C. The magnesium
composite can
optionally have a dissolution rate of <0.1 mg/cm2-hr. in 0.1% KC1 solution at
45 C. The
magnesium composite can optionally have a dissolution rate of at least 30
mg/cm2-hr. in 0.1% KC1
solution at 90 C. The magnesium composite can optionally have a dissolution
rate of at least 20
mg/cm2-hr. in 0.1% KC1 solution at 75 C. The magnesium composite can
optionally have a
dissolution rate of at least 10 mg/cm2-hr. in 0.1% KCl solution at 60 C. The
magnesium composite
can optionally have a dissolution rate of at least 2 mg/cm2-hr. in 0.1% KC1
solution at 45 C. The
metal composite particles or precipitant in said magnesium composite can
optionally have a
solubility in said magnesium of less than 5%. The magnesium alloy can
optionally include over
50 wt.% magnesium and one or more metals selected from the group consisting of
aluminum, boron,
bismuth, zinc, zirconium, and manganese. The magnesium alloy can optionally
include over 50
wt.% magnesium and one or more metals selected from the group consisting of
aluminum in an
amount of about 0.5-10 wt.%, zinc in an amount of about 0.1-6 wt.%, zirconium
in an amount of
about 0.01-3 wt.%, manganese in an amount of about 0.15-2 wt.%, boron in an
amount of about
0.0002-0.04 wt.%, and bismuth in amount of about 0.4-0.7 wt.%. The magnesium
alloy can
optionally include over 50 wt.% magnesium and one or more metals selected from
the group
consisting of aluminum in an amount of about 0.5-10 wt.%, zinc in an amount of
about 0.1-3 wt.%,
zirconium in an amount of about 0.01-1 wt.%, manganese in an amount of about
0.15-2 wt.%, boron
31
CA 3019702 2018-10-03

in an amount of about 0.0002-0.04 wt.%, and bismuth in an amount of about 0.4-
0.7 wt.%. The
magnesium alloy can optionally include at least 85 wt.% magnesium and one or
more metals
selected from the group consisting of 0.5-10 wt.% aluminum, 0.05-6 wt.% zinc,
0.01-3 wt.%
zirconium, and 0.15-2 wt.% manganese. The magnesium alloy can optionally
include 60-95 wt.%
magnesium and 0.01-1 wt.% zirconium. The magnesium alloy can optionally
include 60-95 wt.%
magnesium, 0.5-10 wt.% aluminum, 0.05-6 wt.% zinc, and 0.15-2 wt.% manganese.
The
magnesium alloy can optionally include 60-95 wt.% magnesium, 0.05-6 wt.% zinc,
and 0.01-1 wt.%
zirconium. The magnesium alloy can optionally include over 50 wt.% magnesium
and one or more
metals selected from the group consisting of 0.5-10 wt.% aluminum, 0.1-2 wt.%
zinc, 0.01-1 wt.%
zirconium, and 0.15-2 wt.% manganese. The magnesium alloy can optionally
include over 50
wt.% magnesium and one or more metals selected from the group consisting of
0.1-3 wt.% zinc,
0.01-1 wt.% zirconium, 0.05-1 wt.% manganese, 0.0002-0.04 wt.% boron, and 0.4-
0.7 wt.%
bismuth.
[0079] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable magnesium alloy including 1-15 wt.% aluminum and a dissolution
enhancing
intermetallic phase between magnesium and cobalt, nickel, and/or copper with
the alloy
composition containing 0.05-25 wt.% cobalt, nickel, and/or copper, and 0.1-15
wt.% calcium.
[0080] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable magnesium alloy including 1-15 wt.% aluminum and a dissolution
enhancing
intermetallic phase between magnesium and cobalt, nickel, and/or copper with
the alloy
composition containing 0.05-25 wt.% cobalt, nickel, and/or copper, and 0.1-15
wt.% of calcium,
strontium, barium and/or scandium.
[0081] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable magnesium alloy wherein the alloy composition includes 0.5-8 wt.%
calcium, 0.05-20
wt.% nickel, 3-11 wt.% aluminum, and 50-95 wt.% magnesium and the alloy
degrades at a rate that
is greater than 5 mg/cm2-hr. at temperatures below 90 C in fresh water (water
with less than
1000ppm salt content).
[0082] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable magnesium alloy wherein the alloy composition includes 0-2 wt.%
zinc, 0.5-8 wt.%
calcium, 0.05-20 wt.% nickel, 5-11 wt.% aluminum, and 50-95 wt.% magnesium and
the alloy
32
CA 3019702 2018-10-03

degrades at a rate that is greater than 1 mg/cm2-hr. at temperatures below 45
C in fresh water (water
with less than 1000ppm salt content).
[0083] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable alloy can optionally include calcium, strontium and/or barium
addition that forms an
aluminum-calcium phase, an aluminum-strontium phase and/or an aluminum-barium
phase that
leads to an alloy with a higher incipient melting point and increased
corrosion rate.
[0084] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable alloy can optionally include calcium that creates an aluminum-
calcium (e.g., AlCa2
phase) as opposed to a magnesium-aluminum phase (e.g., Mg i7A112 phase) to
thereby enhance the
speed of degradation of the alloy when exposed to a conductive fluid vs. the
common practice of
enhancing the speed of degradation of an aluminum- containing alloy by
reducing the aluminum
content to reduce the amount of Mg17Al12 in the alloy.
[0085] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable alloy can optionally include calcium addition that forms an
aluminum-calcium phase
that increases the ratio of dissolution of intermetallic phase to the base
magnesium, and thus
increases the dissolution rate of the alloy.
[0086] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable alloy can optionally include calcium addition that forms an
aluminum-calcium phase
reduces the salinity required for the same dissolution rate by over 2x at 90 C
in a saline solution.
[0087] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable alloy can optionally include calcium addition that increases the
incipient melting
temperature of the degradable alloy, thus the alloy can be extruded at higher
speeds and thinner
walled tubes can be formed as compared to a degradable alloy without calcium
additions.
[0088] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable alloy wherein the mechanical properties of tensile yield and
ultimate strength are
optionally not lowered by more than 10% or are enhanced as compared to an
alloy without calcium
addition.
[0089] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable alloy wherein the elevated mechanical properties of yield
strength and ultimate
strength of the alloy at temperatures above 100 C are optionally increased by
more than 5% due to
the calcium addition.
33
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[0090] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable alloy wherein the galvanically active phase is optionally present
in the form of an
LPSO (Long Period Stacking Fault) phase such as Mg12Zni-xNix RE (where RE is a
rare earth
element) and that phase is 0.05-5 wt.% of the final alloy composition.
[0091] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable alloy wherein the mechanical properties at 150 C are optionally
at least 24 ksi tensile
yield strength, and are not less than 20% lower than the mechanical properties
at room temperature
(77 F).
[0092] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable alloy wherein the dissolution rate at 150 C in 3% KCl brine is
optionally 10-150
mg/cm2/hr.
[0093] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable alloy that optionally can include 2-4 wt.% yttrium, 2-5 wt.%
gadolinium, 0.3-4 wt.%
nickel, and 0.05-4 wt.% zinc.
[0094] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable alloy that can optionally include 0.1-0.8 wt.% manganese and/or
zirconium.
[0095] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable alloy that can optionally be use in downhole applications such as
pressure
segmentation, or zonal control.
[0096] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable alloy can optionally be used for zonal or pressure isolation in a
downhole component
or tool.
[0097] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a method for forming a degradable alloy wherein a base dissolution of enhanced
magnesium alloy
is optionally melted and calcium is added as metallic calcium above the
liquids of the magnesium-
aluminum phase and the aluminum preferentially forms A1Ca2 vs. Mgi7A112 during
solidification of
the alloy.
[0098] In still another and/or alternative non-limiting aspect of the
invention, there is provided
a degradable alloy can optionally be formed by adding calcium is in the form
of an oxide or salt that
is reduced by the molten melt vs. adding the calcium as a metallic element.
34
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[0099]
In still another and/or alternative non-limiting aspect of the invention,
there is provided
a degradable alloy can optionally be formed at double the speed or higher as
compared to an alloy
that does not include calcium due to the rise in incipient melting
temperature.
[00100] One non-limiting objective of the present invention is the provision
of a castable,
moldable, or extrudable magnesium composite formed of magnesium or magnesium
alloy and one
or more additives dispersed in the magnesium or magnesium alloy.
[00101] Another and/or alternative non-limiting objective of the present
invention is the
provision of selecting the type and quantity of one or more additives so that
the grain boundaries of
the magnesium composite have a desired composition and/or morphology to
achieve a specific
galvanic corrosion rate in the entire magnesium composite and/or along the
grain boundaries of the
magnesium composite.
[00102] Still yet another and/or alternative non-limiting objective of the
present invention is the
provision of forming a magnesium composite wherein the one or more additives
can be used to
enhance mechanical properties of the magnesium composite, such as ductility
and/or tensile
strength.
[00103] Another and/or alternative non-limiting objective of the present
invention is the
provision of forming a magnesium composite that can be enhanced by heat
treatment as well as
deformation processing, such as extrusion, forging, or rolling, to further
improve the strength of the
final magnesium composite.
[00104] Yet another and/or alternative non-limiting objective of the present
invention is the
provision of forming a magnesium composite that can be can be made into almost
any shape.
[00105] Another and/or alternative non-limiting objective of the present
invention is the
provision of dispersing the one or more additives in the molten magnesium or
magnesium alloy is
at least partially by thixomolding, stir casting, mechanical agitation,
electrowetting, ultrasonic
dispersion and/or combinations of these processes.
[00106] Another and/or alternative non-limiting objective of the present
invention is the
provision of producing a magnesium composite with at least one insoluble phase
that is at least
partially formed by the additive or additive material, and wherein the one or
more additives have a
different galvanic potential from the magnesium or magnesium alloy.
[00107] Still yet another and/or alternative non-limiting objective of the
present invention is the
provision of producing a magnesium composite wherein the rate of corrosion in
the magnesium
CA 3019702 2018-10-03

composite can be controlled by the surface area via the particle size and
morphology of the one or
more additions.
[00108] Yet another and/or alternative non-limiting objective of the present
invention is the
provision of producing a magnesium composite that includes one or more
additives that have a
solubility in the molten magnesium or magnesium alloy of less than about 10%.
[00109] Still yet another and/or alternative non-limiting objective of the
present invention, there
is provided a magnesium composite that can be used as a dissolvable,
degradable and/or reactive
structure in oil drilling.
[00110] These and other objects, features and advantages of the present
invention will become
apparent in light of the following detailed description of preferred
embodiments thereof, as
illustrated in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[00111] Figs. 1-3 show a typical cast microstructure with galvanically-active
in situ formed
intermetallic phase wetted to the magnesium matrix; and,
[00112] Fig. 4 shows a typical phase diagram to create in situ formed
particles of an intermetallic
Mgx(M), Mg(Mx) and/or unalloyed M and/or M alloyed with another M where M is
any element
on the periodic table or any compound in a magnesium matrix and wherein M has
a
electronegativity that is greater than 1.5 or an electronegativity that is
less than 1.25.
DETAILED DESCRIPTION OF THE INVENTION
[00113] Referring now to the figures wherein the showings illustrate non-
limiting embodiments
of the present invention, the present invention is directed to a magnesium
composite that includes
one or more additives dispersed in the magnesium composite. The magnesium
composite of the
present invention can be used as a dissolvable, degradable and/or reactive
structure in oil drilling.
For example, the magnesium composite can be used to form a frac ball or other
structure (e.g.,
sleeves, valves, hydraulic actuating tooling and the like, etc.) in a well
drilling or completion
operation. Although the magnesium composite has advantageous applications in
the drilling or
completion operation field of use, it will be appreciated that the magnesium
composite can be used
in any other field of use wherein it is desirable to form a structure that is
controllably dissolvable,
degradable and/or reactive.
36
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[00114] The present invention is directed to a novel magnesium composite that
can be used to
form a castable, moldable, or extrudable component. The magnesium composite
includes at least
50 wt.% magnesium. Generally, the magnesium composite includes over 50 wt.%
magnesium and
less than about 99.5 wt.% magnesium and all values and ranges therebetween.
One or more
additives are added to a magnesium or magnesium alloy to form the novel
magnesium composite
of the present invention. The one or more additives can be selected and used
in quantities so that -
galvanically-active intermetallic or insoluble precipitates form in the
magnesium or magnesium
alloy while the magnesium or magnesium alloy is in a molten state and/or
during the cooling of the
melt; however, this is not required. The one or more additives are added to
the molten magnesium
or magnesium alloy at a temperature that is typically less than the melting
point of the one or more
additives; however, this is not required. During the process of mixing the one
or more additives in
the molten magnesium or magnesium alloy, the one or more additives are not
caused to fully melt
in the molten magnesium or magnesium alloy; however, this is not required. For
additives that
partially or fully melt in the molten magnesium or molten magnesium alloy,
these additives form
alloys with magnesium and/or other additives in the melt, thereby resulting in
the precipitation of
such formed alloys during the cooling of the molten magnesium or molten
magnesium alloy to form
the galvanically-active phases in the magnesium composite. After the mixing
process is
completed, the molten magnesium or magnesium alloy and the one or more
additives that are mixed
in the molten magnesium or magnesium alloy are cooled to form a solid
magnesium component
that includes particles in the magnesium composite. Such a formation of
particles in the melt is
called in situ particle formation as illustrated in Figs. 1-3. Such a process
can be used to achieve a
specific galvanic corrosion rate in the entire magnesium composite and/or
along the grain
boundaries of the magnesium composite. This feature results in the ability to
control where the
galvanically-active phases are located in the final casting, as well as the
surface area ratio of the in
situ phase to the matrix phase, which enables the use of lower cathode phase
loadings as compared
to a powder metallurgical or alloyed composite to achieve the same dissolution
rates. The in situ
formed galvanic additives can be used to enhance mechanical properties of the
magnesium
composite such as ductility, tensile strength, and/or shear strength. The
final magnesium
composite can also be enhanced by heat treatment as well as deformation
processing (such as
extrusion, forging, or rolling) to further improve the strength of the final
composite over the as-cast
material; however, this is not required. The deformation processing can be
used to achieve
37
CA 3019702 2018-10-03

strengthening of the magnesium composite by reducing the grain size of the
magnesium composite.
Further enhancements, such as traditional alloy heat treatments (such as
solutionizing, aging and/or
cold working) can be used to enable control of dissolution rates though
precipitation of more or less
galvanically-active phases within the alloy microstructure while improving
mechanical properties;
however, this is not required. Because galvanic corrosion is driven by both
the electrode potential
between the anode and cathode phase, as well as the exposed surface area of
the two phases, the
rate of corrosion can also be controlled through adjustment of the in situ
formed particles size, while
not increasing or decreasing the volume or weight fraction of the addition,
and/or by changing the
volume/weight fraction without changing the particle size. Achievement of in
situ particle size
control can be achieved by mechanical agitation of the melt, ultrasonic
processing of the melt,
controlling cooling rates, and/or by performing heat treatments. In situ
particle size can also or
alternatively be modified by secondary processing such as rolling, forging,
extrusion and/or other
deformation techniques. A smaller particle size can be used to increase the
dissolution rate of the
magnesium composite. An increase in the weight percent of the in situ formed
particles or phases
in the magnesium composite can also or alternatively be used to increase the
dissolution rate of the
magnesium composite. A phase diagram for forming in situ formed particles or
phases in the
magnesium composite is illustrated in Fig. 4.
[00115] In accordance with the present invention, a novel magnesium composite
is produced by
casting a magnesium metal or magnesium alloy with at least one component to
form a galvanically-
active phase with another component in the chemistry that forms a discrete
phase that is insoluble
at the use temperature of the dissolvable component. The in situ formed
particles and phases have
a different galvanic potential from the remaining magnesium metal or magnesium
alloy. The in
situ formed particles or phases are uniformly dispersed through the matrix
metal or metal alloy using
techniques such as thixomolding, stir casting, mechanical agitation, chemical
agitation,
electrowetting, ultrasonic dispersion, and/or combinations of these methods.
Due to the particles
being formed in situ to the melt, such particles generally have excellent
wetting to the matrix phase
and can be found at grain boundaries or as continuous dendritic phases
throughout the component
depending on alloy composition and the phase diagram. Because the alloys form
galvanic
intermetallic particles where the intermetallic phase is insoluble to the
matrix at use temperatures,
once the material is below the solidus temperature, no further dispersing or
size control is necessary
in the component. This feature also allows for further grain refinement of the
final alloy through
38
CA 3019702 2018-10-03

traditional deformation processing to increase tensile strength, elongation to
failure, and other
properties in the alloy system that are not achievable without the use of
insoluble particle additions.
Because the ratio of in situ formed phases in the material is generally
constant and the grain
boundary to grain surface area is typically consistent even after deformation
processing and heat
treatment of the composite, the corrosion rate of such composites remains very
similar after
mechanical processing.
EXAMPLE 1
[00116] An AZ91D magnesium alloy having 9 wt.% aluminum, 1 wt.% zinc and 90
wt.%
magnesium was melted to above 800 C and at least 200 C below the melting point
of nickel.
About 7 wt.% of nickel was added to the melt and dispersed. The melt was cast
into a steel mold.
The cast material exhibited a tensile strength of about 14 ksi, an elongation
of about 3%, and shear
strength of 11 ksi. The cast material dissolved at a rate of about 75 mg/cm2-
min in a 3% KC1
solution at 90 C. The material dissolved at a rate of 1 mg/cm2-hr in a 3% KC1
solution at 21 C.
The material dissolved at a rate of 325 mg/cm2-hr. in a 3% KCl solution at 90
C.
EXAMPLE 2
[00117] The composite in Example 1 was subjected to extrusion with an 11:1
reduction area.
The material exhibited a tensile yield strength of 45 ksi, an Ultimate tensile
strength of 50 ksi and
an elongation to failure of 8%. The material has a dissolve rate of 0.8 mg/cm2-
min. in a 3% KC1
solution at 20 C. The material dissolved at a rate of 100 mg/cm2-hr. in a 3%
KCl solution at 90 C.
EXAMPLE 3
[00118] The alloy in Example 2 was subjected to an artificial T5 age treatment
of 16 hours from
100-200 C. The alloy exhibited a tensile strength of 48 ksi and elongation to
failure of 5% and a
shear strength of 25 ksi. The material dissolved at a rate of 110 mg/ cm2-hr.
in 3% KCl solution at
90 C and 1 mg/cm2-hr. in 3% KC1 solution at 20 C.
EXAMPLE 4
[00119] The alloy in Example 1 was subjected to a solutionizing treatment T4
of 18 hours from
400 C-500 C and then an artificial T6 aging process of 16 hours from 100-200C.
The alloy
39
CA 3019702 2018-10-03

exhibited a tensile strength of 34 ksi and elongation to failure of 11% and a
shear strength of 18Ksi.
The material dissolved at a rate of 84mg/cm2-hr. in 3% KCl solution at 90 C
and 0.8 mg/cm2-hr. in
3% KC1 solution at 20 C.
EXAMPLE 5
[00120] An AZ91D magnesium alloy having 9 wt.% aluminum, 1 wt.% zinc, and 90
wt.%
magnesium was melted to above 800 C and at least 200 C below the melting point
of copper.
About 10 wt.% of copper alloyed to the melt and dispersed. The melt was cast
into a steel mold.
The cast material exhibited a tensile yield strength of about 14 ksi, an
elongation of about 3%, and
shear strength of 11 ksi. The cast material dissolved at a rate of about 50
mg/cm2-hr. in a 3% KCl
solution at 90 C. The material dissolved at a rate of 0.6 mg/cm2-hr. in a 3%
KC1 solution at 21 C.
EXAMPLE 6
[00121] The alloy in Example 5 was subjected to an artificial T5 aging process
of 16 hours from
100-200 C. The alloy exhibited a tensile strength of 50 ksi and elongation to
failure of 5% and a
shear strength of 25 ksi. The material dissolved at a rate of 40 mg/cm2-hr. in
3% KCl solution at
90 C and 0.5 mg/cm2-hr. in 3% KC1 solution at 20 C.
EXAMPLE 7
[00122] An AZ91D magnesium alloy having 9 wt.% aluminum, 1 wt.% zinc, and 90
wt.%
magnesium was melted to above 700 C. About 16 wt.% of 75um iron particles were
added to the
melt and dispersed. The melt was cast into a steel mold. The cast material
exhibited a tensile
strength of about 26 ksi, and an elongation of about 3%. The cast material
dissolved at a rate of
about 2.5 mg/cm2-min in a 3% KC1 solution at 20 C. The material dissolved at a
rate of 60 mg/cm2-
hr in a 3% KCl solution at 65 C. The material dissolved at a rate of 325mg/cm2-
hr. in a 3% KCl
solution at 90 C.
EXAMPLE 8
[00123] An AZ91D magnesium alloy having 9 wt.% aluminum, 1 wt.% zinc, and 90
wt.%
magnesium was melted to above 700 C. About 2 wt.% 75um iron particles were
added to the melt
and dispersed. The melt was cast into steel molds. The material exhibited a
tensile strength of 26
CA 3019702 2018-10-03

ksi, and an elongation of 4%. The material dissolved at a rate of 0.2 mg/cm2-
min in a 3% KC1
solution at 20 C. The material dissolved at a rate of lmg/cm2-hr in a 3% KCl
solution at 65 C.
The material dissolved at a rate of 10mg/cm2-hr in a 3% KC1 solution at 90 C.
EXAMPLE 9
[00124] An AZ91D magnesium alloy having 9 wt.% aluminum, 1 wt.% zinc, and 90
wt.%
magnesium was melted to above 700 C. About 2 wt.% nano iron particles and
about 2 wt.% nano
graphite particles were added to the composite using ultrasonic mixing. The
melt was cast into
steel molds. The material dissolved at a rate of 2 mg/cm2-min in a 3% KCl
solution at 20 C. The
material dissolved at a rate of 20 mg/cm2-hr in a 3% KC1 solution at 65 C. The
material dissolved
at a rate of 100 mg/cm2-hr in a 3% KC1 solution at 90 C.
EXAMPLE 10
The composite in Example 7 was subjected to extrusion with an 11:1 reduction
area. The extruded
metal cast structure exhibited a tensile strength of 38ksi, and an elongation
to failure of 12%. The
extruded metal cast structure dissolved at a rate of 2 mg/cm2-min in a 3% KCl
solution at 20 C.
The extruded metal cast structure dissolved at a rate of 301 mg/cm2-min in a
3% KCl solution at
90 C. The extruded metal cast structure exhibited an improvement of 58%
tensile strength and an
improvement of 166% elongation with less than 10% change in dissolution rate
as compared to the
non-extruded metal cast structure.
EXAMPLE 11
[00125] Pure magnesium was melted to above 650 C and below 750 C. About 7 wt.%
of
antimony was dispersed in the molten magnesium. The melt was cast into a steel
mold. The cast
material dissolved at a rate of about 20.09 mg/cm2-hr in a 3% KC1 solution at
90 C.
EXAMPLE 12
[00126] Pure magnesium was melted to above 650 C and below 750 C. About 5 wt.%
of
gallium was dispersed in the molten magnesium. The melt was cast into a steel
mold. The cast
material dissolved at a rate of about 0.93 mg/cm2-hr in a 3% KCl solution at
90 C.
41
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EXAMPLE 13
[00127] Pure magnesium was melted to above 650 C and below 750 C. About 13
wt.% of tin
was dispersed in the molten magnesium. The melt was cast into a steel mold.
The cast material
dissolved at a rate of about 0.02 mg/cm2-hr in a 3% KCl solution at 90 C.
EXAMPLE 14
[00128] A magnesium alloy that included 9 wt.% aluminum, 0.7 wt.% zinc, 0.3
wt.% nickel, 0.2
wt.% manganese, and the balance magnesium was heated to 157 C (315 F) under an
SF6-0O2 cover
gas blend to provide a protective dry atmosphere for the magnesium alloy. The
magnesium alloy
was then heated to 730 C to melt the magnesium alloy and calcium was then
added into the molten
magnesium alloy in an amount that the calcium constituted 2 wt.% of the
mixture. The mixture of
molten magnesium alloy and calcium was agitated to adequately disperse the
calcium within the
molten magnesium alloy. The mixture was then poured into a preheated and
protective gas-filled
steel mold and naturally cooled to form a cast part that was a 9" x 32"
billet. The billet was
subsequently preheated to ¨350 C and extruded into a solid and tubular
extrusion profile. The
extrusions were run at 12 and 7 inches/minute respectively, which is 2x-3x
faster than the maximum
speed the same alloy achieved without calcium alloying. It was determined that
once the molten
mixture was cast into a steel mold, the molten surface of the mixture in the
mold did not require an
additional cover gas or flux protection during solidification. This can be
compared to the same
magnesium-aluminum alloy without calcium that requires either an additional
cover gas or flux
during solidification to prevent burning.
[00129] The effect of the calcium on the corrosion rate of a magnesium-
aluminum-nickel alloy
was determined. Since magnesium already has a high galvanic potential with
nickel, the
magnesium alloy corrodes rapidly in an electrolytic solution such as a
potassium chloride brine.
The KC1 brine was a 3% solution heated to 90 C (194 F). The corrosion rate was
compared by
submerging 1" x 0.6" samples of the magnesium alloy with and without calcium
additions in the
solution for 6 hours and the weight loss of the alloy was calculated relative
to initial exposed surface
area. The magnesium alloy that did not include calcium dissolved at a rate of
48 mg/cm2-hr. in the
3% KC1 solution at 90 C. The magnesium alloy that included calcium dissolved
at a rate of 91
mg/cm2-hr. in the 3% KC1 solution at 90 C. The corrosion rates were also
tested in fresh water.
The fresh water is water that has up to or less than 1000 ppm salt content. A
KCl brine solution
42
CA 3019702 2018-10-03

was used to compare the corrosion rated of the magnesium alloy with and
without calcium additions.
1" x 0.6" samples of the magnesium alloy with and without calcium additions
were submerged in
the 0.1% KCL brine solution for 6 hours and the weight loss of the alloys were
calculated relative
to initial exposed surface area. The magnesium alloy that did not include
calcium dissolved at a
rate of 0.1 mg/cm2-hr. in the 0.1% KCl solution at 90 C, a rate of <0.1 mg/cm2-
hr. in the 0.1% KC1
solution at 75 C, a rate of <0.1 mg/cm2-hr. in the 0.1% KC1 solution at 60 C,
and a rate of <0.1
mg/cm2-hr. in the 0.1% KC1 solution at 45 C. The magnesium alloy that did
include calcium
dissolved at a rate of 34 mg/cm2-hr. in the 0.1% KC1 solution at 90 C, a rate
of 26 mg/cm2-hr. in
the 0.1% KCl solution at 75 C, a rate of 14 mg/cm2-hr. in the 0.1% KC1
solution at 60 C, and a rate
of 5 mg/cm2-hr. in the 0.1% KC1 solution at 45 C.
[00130] The effect of calcium on magnesium alloy revealed that the microscopic
"cutting" effect
of the lamellar aluminum-calcium phase slightly decreases the tensile strength
at room temperature,
but increased tensile strength at elevated temperatures due to the grain
refinement effect of Al2Ca.
The comparative tensile strength and elongation to failure are shown in Table
A.
[00131] Table A
Test Tensile Strength Elongation to Tensile Strength
Elongation to
Temperature without Ca (psi) failure without Ca with 2 wt.% Ca
failure with 2
(%) (psi) wt.%
Ca (YO)
25 C 23.5 2.1 21.4 1.7
150 C 14.8 7.8 16.2 6.8
[00132] The effect of varying calcium concentration in a magnesium-aluminum-
nickel alloy was
tested. The effect on ignition temperature and maximum extrusion speed was
also tested. For
mechanical properties, the effect of 0-2 wt.% calcium additions to the
magnesium alloy on ultimate
tensile strength (UTS) and elongation to failure (Ef) is illustrated in Table
B.
[00133] Table B
Calcium Concentration (wt.%) UTS at 25 C Ef at 25 C UTS at 150 C Ef at
150 C
0% 41.6 10.3 35.5 24.5
0.5% 40.3 10.5 34.1 24.0
1.0% 38.5 10.9 32.6 23.3
2.0% 37.7 11.3 31.2 22.1
43
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[00134] The effect of calcium additions in the magnesium-aluminum-nickel alloy
on ignition
temperature was tested and found to be similar to a logarithmic function, with
the ignition
temperature tapering off The ignition temperature trend is shown in Table C.
[00135] Table C
Calcium Concentration (wt.%) 0 1 2 3 4 5
Ignition Temperature ( C) 550 700 820 860 875 875
[00136] The incipient melting temperature effect on maximum extrusion speeds
was also found
to trend similarly to the ignition temperature since the melting temperature
of the magnesium matrix
is limiting. The extrusion speed for a 4" solid round extrusion from at 9"
round billet trends as
shown in Table D.
44
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[00137] Table D
Calcium Concentration (wt.%) 0% 0.5% 1% 2% 4%
Extrusion Speed for 4" solid (in/min) 4 6 9 12 14
Extrusion speed for 4.425" OD x 1.5 2.5 4 7 9
2.645" ID tubular (in/min)
EXAMPLE 15
[00138] Pure magnesium is heated to a temperature of 680-720 C to form a melt
under a
protective atmosphere of SF6 + CO2 + air. 1.5-2 wt.% zinc and 1.5-2 wt.%
nickel were added
using zinc lump and pelletized nickel to form a molten solution. From 3-6 wt.%
gadolinium, as
well as about 3-6 wt.% yttrium was added as lumps of pure metal, and 0.5-0.8%
zirconium was
added as a Mg-25% zirconium master alloy to the molten magnesium, which is
then stirred to
distribute the added metals in the molten magnesium. The melt was then cooled
to 680 C, and
degassed using HCN and then poured in to a permanent A36 steel mold and
solidified. After
solidification of the mixture, the billet was solution treated at 500 C for 4-
8 hours and air cooled.
The billet was reheated to 360 C and aged for 12 hours, followed by extrusion
at a 5:1 reduction
ratio to form a rod.
[00139] It is known that LPSO phases in magnesium can add high temperature
mechanical
properties as well as significantly increase the tensile properties of
magnesium alloys at all
temperatures. The Mg12Zn1Nix REI LPSO (long period stacking order) phase
enables the
magnesium alloy to be both high strength and high temperature capable, as well
as to be able to be
controllably dissolved using the phase as an in situ galvanic phase for use in
activities where
enhanced and controllable use of degradation is desired. Such activities
include use in oil and gas
wells as temporary pressure diverters, balls, and other tools that utilize
dissolvable metals.
[00140] The magnesium alloy was solution treated at 500 C for 12 hours and air-
cooled to allow
precipitation of the 14H LPSO phase incorporating both zinc and nickel as the
transition metal in
the layered structure. The solution-treated alloy was then preheated at 350-
400 C for over 12 hours
prior to extrusion at which point the material was extruded using a 5:1
extrusion ratio (ER) with an
extrusion speed of 20 ipm (inch per minute).
[00141] At the nano-layers present between the nickel and the magnesium layers
or magnesium
matrix, the galvanic reaction took place. The dissolution rate in 3% KCl brine
solution at 90 C as
well as the tensile properties at 150 C of the galvanically reactive alloy are
shown in Table E.
CA 3019702 2018-10-03

[00142] Table E
Magnesium Dissolution rate Ultimate Tensile Tensile Yield Elongation
to
Alloy (mg/cm2-hr.) Strength at Strength at Failure at 150
C
150 C (ksi) 150 C (ksi) ( /0)
62 - 80 36 24 38
[00143] It will thus be seen that the objects set forth above, among those
made apparent from the
preceding description, are efficiently attained, and since certain changes may
be made in the
constructions set forth without departing from the spirit and scope of the
invention, it is intended
that all matter contained in the above description and shown in the
accompanying drawings shall be
interpreted as illustrative and not in a limiting sense. The invention has
been described with
reference to preferred and alternate embodiments. Modifications and
alterations will become
apparent to those skilled in the art upon reading and understanding the
detailed discussion of the
invention provided herein. This invention is intended to include all such
modifications and
alterations insofar as they come within the scope of the present invention. It
is also to be
understood that the following claims are intended to cover all of the generic
and specific features of
the invention herein described and all statements of the scope of the
invention, which, as a matter
of language, might be said to fall there between. The invention has been
described with reference
to the preferred embodiments. These and other modifications of the preferred
embodiments as well
as other embodiments of the invention will be obvious from the disclosure
herein, whereby the
foregoing descriptive matter is to be interpreted merely as illustrative of
the invention and not as a
limitation. It is intended to include all such modifications and alterations
insofar as they come
within the scope of the appended claims.
46
CA 3019702 2018-10-03