Note: Descriptions are shown in the official language in which they were submitted.
~3~3~
AMORPHOUS METAL ALLOY POWDERS
AND BULK OBJECTS AND SYNTHESIS OF
SAME BY SOLID STATE DECOMPOSITION REACTIONS
FIELD OF THE INVENTION
This invention relates to amorphous metal alloy powders and
shapes and the novel preparation of such powders by solid state
reactions. More specifically, this invention relates to the
synthesis of amorphous metal alloy powders by the thermal
decomposition no metal-bearing compounds and the synthesis of
amorphous metal alloy shapes by solid state reactions that utilize a
ductile matrix precursor.
BACKGROUND OF EYE INVENTION
Amorphous metal alloy materials have become of interest in
recent years due to their unique combinations of mechanical, chemical
and electrical properties that are especially well-suited for
newly-emerging applications. Examples of amorphous metal material
properties include the following:
- uniform electronic structure,
- compositional variable properties,
- high hardness and strength,
; - flexibility,
- soft magnetic and ferroelectronie properties,
- very high resistance to corrosion and wear,
- unusual alloy compositions, and
- high resistance to radiation damage.
These characteristics are desirable for applications such as
low temperature welding alloys magnetic bubble memories, high field
superconducting devices and soft magnetic materials for power
transformer cores.
The unique combination of properties of amorphous metal
alloy materials may be attributed to the disordered atomic structure
of amorphous materials which ensures that the material is chemically
homogeneous and free from the extended defects, such as dislocations
I
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and grain boundaries, that are known to limit the performance of
crystalline materials. The amorphous state is characterized by a
lack of long range periodicity, whereas a characteristic of the
crystalline state it its long range periodicity.
Generally, the room temperature stability of amorphous
materials depends on various kinetic barriers to the growth of
crystal nuclei and to nucleation barriers that hinder the formation
of stable crystal nuclei. Such barriers typically are present if the
material to be made amorphous it first heated to a molten state then
rapidly quenched or cooled through the crystal nucleation temperature
range at a rate that is sufficiently fast to prevent significant
nucleation to occur. Such cooling rates are on the order of
lo C~second. Rapid cooling dramatically increases the viscosity
of the molten alloy and quickly decreases the length over which atoms
can diffuse. This has the effect of preventing crystalline nuclei
from forming and yields a metastable, or amorphous phase.
Processes that provide such cooling rates include
sputtering vacuum evaporation plasma spraying and direct quenching
prom the liquid state. It has been found that alloys produced by one
method often cannot be similarity produced by another method even
though the pathway to formation is in theory the same.
Direct quenching from the liquid state has found the
greatest commercial success since a variety of alloys are known that
can be manufactured by this technique in various forms such as thin
films, ribbons and wires. United States patent number 3,856,513 to
Chin et at. describes novel metal alloy compositions obtained by
direct quenching from the melt and includes a general discussion of
this process. Chin et at. describes magnetic amorphous metal alloys
formed by sub~ectlng the alloy composition to rapid cooling from a
temperature above its melting temperature. A stream of the molten
metal is directed into the nip of rotating double rolls maintained at
room temperature. The quenched metal, obtained in the form of a
ribbon, was substantially amorphous as indicated by x-ray diffraction
measurements, was ductile, and had a tensile strength of about
350,000 psi.
United States patent number ~,036,63B to Ray ok 31.
describes binary amorphous alloys of iron or cobalt and boron. The
claimed amorphous alloys were formed by a vacuum melt-casting process
wherein molten alloy was ejected through an orifice and against a
rotating cylinder in a partial vacuum of about lo molter. Such
amorphous alloys were obtained as continuous ribbons and all
exhibited high mechanical hardness and ductility.
The thicknesses of essentially all amorphous foils and
ribbons formed by rapid cooling from the melt are limited by the rate
of heat transfer through the material. Generally the thicknesses of
such f11~s are less than So m. The few materials that can be
prepared in this manner include those disclosed by Chin et at. and
Ray et at.
Amorphous metal alloy materials prepared by
electrode position processes have been reported by Lash more and
Weinroth in Plating and Surface Finishing, 72 (August 1982). These
materials include Co-P, Nip, Core and Co-W compositions. However,
the as-formed alloys are in homogeneous and so can be used in only a
limited number of applications.
The above-listed prior art processes for producing amorphous
metal alloys depend upon controlling the kinetics of the
solidification process; controlling the formation of the alloy from
the liquid (molten) state or from the vapor state by rapidly removing
heat energy during solidification. Most recently, an amorphous metal
alloy composition was synthesized without resort to rapid heat
removal. Ye et at. reported that a metastable crystalline compound
Zr3Rh, in the form of a thln-film could be transformed into a
thln-fllm, amorphous metal alloy by the controlled introduction of
hydrogen gas; Applied Physics Letter 42 (3), pp. 242-244, February l,
1983. The amorphous metal alloy had an approximate composition of
Zr3RhH~ 5.
Ye et at. specified three requirements as prerequisites for
the formation of amorphous alloys by solid state r reactions: at
least a three component system; a large disparity in the atomic
diffusion rates of two of the atomic species; and an absence of a
polymorphic crystalline alternative as a final state. Thus, Ye et
at. teach that solid state reactions would have muted applications
for the synthesis of amorphous metal alloy materials.
The known amorphous metal alloy and processes for making
such alloys which are discussed above suffer from the disadvantage
that the so-formed amorphous alloy is produced in a limited form,
that is, as a thin film such as a ribbon, wire or platelet. These
limited shapes place severe restrictions on the applications for
which amorphous metal materials may be used.
To produce bulk amorphous metal alloy objects the formed
amorphous alloy must be mechanically reduced to a powder as by
chipping, crushing, grinding and ball milling, and then recombined in
the desired shape. These are difficult processes when it is realized
that most amorphous metal alloys have high mechanical strengths and
also possesses high harnesses.
What is lacking in the area of amorphous metal alloy
preparation is a simple process for the direct formation of a large
variety of amorphous metal alloys. Especially lacking is a process
that would synthesize amorphous metal alloy materials directly as
powders suitable for forming bulk amorphous metal alloy shapes.
Hence, it is one object of the present invention to provide
novel amorphous metal alloy compositions.
It is another object of the present invention to provide a
process for the direct preparation of a large variety of homogeneous
amorphous metal alloy compositions.
It is a further object of the present invention to provide a
process for the direct preparation of a large variety of homogeneous
amorphous metal alloy compositions in a powder form.
It it till another object of the present invention to
provide a process for the direct preparation of a large variety of
homogeneous amorphous metal alloy powders by solid state reaction.
It is yet another object of this invention to provide novel
bulk amorphous metal alloy objects.
It is another object of the present invention to provide a
process for the synthesis of bulk amorphous metal alloy objects.
These and additional objects of the present invention will
become apparent in the description of the invention and examples that
follow.
SUMMARY US THE INYE~TION
The present lnvent10n relate to a process for the synthesis
of a substantially amorphous metal alloy comprising thornily
decomposing at least one precursor m~tal-hear~ng compound at
temperature below the crystalline temperature of the amorphous metal
alloy to be formed the at least one precursor ~etat-bear7ng compound
having a decomposit10n temperature below the crystall~zat10n
temperature of the amorphous alloy to be wormed and containing the
metals which ccmpr~se the substantially amorphous metal alloy.
Thus invention also relates to a process for the synthesis
of a substantially amorphous metal alloy comprising the steps of:
a) decomposing at least one precursor met21-bearing
compound at a temperature below the
crystal kitten temperature of the amorphous eel
alloy to be synthesized so as to form an ~nt1mate
mixture of the components of the amorphous metal
alloy to be synthesized, the at least one
precursor metal-bear1ng compound containing the
metals which comprise the substantially amorphous
alloy; and
b) heat-treating the notate mixture so as to form
the amorphous metal alloy.
The present ~nvent10n also relates to process for the
product10n of substantially amorphous metal alloy objects comprising:
a) preparing an 1nt~mate mixture of the components of
the amorphous metal alloy by solid state ricketiness, at least one
component of the ~nt1m~te mixture being a ductile component; and
b) forming the intimate mixture into an object at a
temperature below the crystall~zat10n temperature of the metal alloy
so as to form an amorphous Allah Lowe object.
The present invention further relates to a process for the
synthesis of an enhanced substantially amorphous metal alloy comprising
thermally decomposing at least one precursor metal-bearing compound in
the presence of an initial substantially amorphous metal alloy at a
temperature below the crystallization temperatures of the initial sub-
staunchly amorphous metal alloy and the enhanced substantially amorphous
metal alloy to be formed, the at least one precursor metal-bearing compound
" ~3~3~
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containing addition elements to be incorporated into the initial
metal alloy so as to form an enhanced substantially amorphous metal
alloy.
The present invention still further relates to a process
for the synthesis of an enhanced substantially amorphous metal
alloy comprising the steps of:
(a) decomposing at least one precursor, metal-bearing
compound in the presence of an initial substantially amorphous
metal alloy at a temperature below the crystallization temperature
of the enhanced substantially amorphous metal alloy to be sync
the sized so as to form an intimate mixture of the components of the
enhanced amorphous metal alloy to be synthesized and
(b) heat treating the mixture so as to form an enhanced
substantially amorphous metal alloy.
The invention yet further relates to a process for the
production of substantially amorphous metal alloy objects
comprising:
a) preparing an intimate mixture of the components of
the amorphous metal alloy by a solid state reaction, at least one
component of the intimate mixture being a ductile component; and
b) forming the intimate mixture into an object at a
temperature below the crystallization temperature of the metal alloy
so as Jo form an amorphous metal alloy object.
The present invention also relates to novel, substantially
amorphous metal alloy objects synthesized in accordance with the
above-summarized process.
Therefore the present invention also relates to a
substantially amorphous metal alloy powder synthesized by
Jo .
I.
-5b
thermally decomposing at least one precursor metal-bearing compound
at a temperature below the crystallization temperature of the
amorphous metal alloy, the at least one precursor metal-bearing
compound containing the metals that comprise the substantially
amorphous metal alloy.
Detailed DESCRIPTION OF THE INVENTION
In accordance with this invention, there are provided novel
processes for the synthesis of substantially amorphous metal alloys.
I
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There are also provided novel, substantially amorphous metal alloy
objects and a process for the production of such substantially
amorphous metal alloy objects. The term "substantially" us used
herein in reference to the amorphous metal alloy means that the metal
alloys are at least fifty percent amorphous. Preferably the metal
alloy us at least eighty percent amorphous and most preferably about
one hundred percent amorphous, as indicated by x-ray diffraction
analysis. The use of the phrase amorphous metal alloys" herein
refers to amorphous metal-contain1ng alloys that may also comprise
non-metallic elements. Amorphous metal alloys my include
non-metallic elements such as boron, carbon, nitrogen, silicon,
phosphorus, arsenic, germanium and antimony.
The solid state processes disclosed herein include the step
of thermally decomposing at least one metal-bearing compound at a
temperature below the crystallization temperature of the amorphous
metal alloy to be formed. The at least one precursor metal-bear~ng
compound is preferably chosen so that its decomposition temperature
is at least 25C below the crystallization temperature of the
amorphous metal alloy to be formed and most preferably is at least
100C below the crystallization temperature of the amorphous metal
alloy to be formed.
Typical precursor metal-bearing compounds have decomposition
temperatures between about 20C and about 500C. A substantial
number of precursor metal-bearing compounds suitable for use in the
processes of this invention have decomposition temperatures between
about 150C and about 400C.
The thermal decomposition of the at least one precursor
metal-bearing compound yields an intimate mixture of the components
of the desired metal alloy. This decomposition step is preferably
performed in a reactor having collection means so that about a one
hundred percent yield of material will be realized. This may be
achieved by maintaining a cooled reactor portion downstream of the
thermal decomposition portion of the reactor wherein the thermally
decomposed products will be deposited. Alternatively and most
preferably, the decomposition step may be performed in a sealed
reactor to prevent evaporation of the metal alloy components. Upon
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cooling, about a one hundred percent yield of the reaction products
may be recovered therefronl.
The decomposition of the precursor compounds may occur under
an atmosphere suitable for the synthesis of the desired amorphous
metal alloy. the precursor compounds may be disposed in a sealed
reaction vessel thaw has been partially or fully evacuated prior to
heating. If the amorphous metal alloy to be synthesized does not
contain oxygen, then it is preferred that the thermal decomposition
of the precursor compounds be done under an inert or reducing
atmosphere or in a sealed reaction vessel that has been partially or
fully evacuated. If some tolerance to oxygen is possible then an
inert or reducing atmosphere or vacuum may not be necessary.
A precursor compound may also exist at room temperature in
the gaseous state and may itself provide the initial atmosphere under
which the thermal decomposition will be performed. In this manner, a
reactive atmosphere exists for the thermal decomposition reaction.
Precursor compounds may also be used that are solid at about 20C,
but which vaporize at slightly elevated temperatures. These
compounds may be disposed in an evacuated reactor and upon heating,
provide a reactive atmosphere for the decomposition reaction.
The precursor metal-bearing compounds suitable for use in
this invention may include organometallic compounds such as monomers,
d7mers, trimmers and polymers having metallo-organic ligands composed
of saturated and/or unsaturated hydrocarbons, aromatic or
heteroaromat k Lindsey, and may also include oxygen, boron, carbon,
nitrogen, phosphorus, arsenic, germanium, antimony and/or
silicon-containing ligands, and combina~lons thereof. Precursor
metalk~bearing compounds may also be halogen compounds, oxides,
nitrates, nitrides, carbides, brides or metal-bearing salts, with
the restriction that the decomposition temperature of the precursor
compound be less than the crystallization temperature of the
amorphous metal alloy to be synthesized.
As disclosed earlier, precursor compounds may also be
provided that do not contain a metal but which contribute a
non-metallic element to the amorphous alloy composition.
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The thermal decomposition of precursor compounds yields a
product consisting essentially of the components of the desired
amorphous metal alloy. The components are intimately mixed, the
maximum size of the particles in the mixture preferably being from
about 10 Angstroms to about 1000 Angstroms, and most preferably from
about 10 Angstroms to about 500 Angstroms. These decomposition
products may be represented by the following empirical formulae:
Maul a
wherein M is at least one metal selected from the metals in
Groups VI-B, VII-B, VIII, I-B, JIB and III~ of the
Periodic Table; and
: X is at least one element selected from groups III-A,
IV-A and V-A of the Periodic Table; and
wherein a ranges from about 0.1 to about 0.9;
and b l-b
: wherein N it at least one metal selected from the metals in
Groups III-B, IV-B, Y-B and VI-B of the Periodic Table;
and
Y is selected from Groups VIII, I-B and II-B of the
Periodic Table; and
wherein b ranges from about 0.2 to about 0.8
The thermal decomposition of the precursor compounds may
occur at high enough temperatures and for a period of time long
enough to permit alloying of the metal elements concurrent with the
decomposition. Under such circumstances the product which results
from the decomposition step is a substantially amorphous metal alloy.
This product is synthesized as a solid, powder material
having a maximum particle size of from abut 10 Angstroms to about
3L~3~
1000 Angstroms. This powder is suitable for compaction, with or
without a binder, into a solid shape.
If the decomposition temperature is not sufficiently high,
or the period of decomposition is too brief, to enable alloying of
the reactant products during the decomposition of the precursor
compounds, then the powder that is obtained is an intimate mixture
comprising the alloy components. A subsequent heat-treating step at
a temperature below the crystallization temperature of the amorphous
metal alloy will allow diffusion of at least one metal component so
as to form an amorphous metal alloy. This heat-treating step is
carried out under an atmosphere conducive to the formation of the
amorphous metal alloy. This may occur under vacuum conditions, from
about O torn. to about 500 torn., or in an inert, reducing or
reactive atmosphere.
Prior to the heat-treating step, the powder obtained from
the decomposition of the precursor compounds may be pressed into a
shape so that, upon heat-treating, a bulk amorphous metal alloy shape
is obtained. It is also possible to compact the heat-treated
amorphous petal alloy powder into a solid shape.
It has also surprisingly been found that the amorphous metal
alloy products of thermal decomposition and
decomposition/heat-treating processes may be mixed with another
precursor metal-bearing compound Jo yield a new, enhanced amorphous
metal alloy material which has incorporated into the prior amorphous
metal alloy elements from the newly-added precursor. This may be
accomplished by disposing the prior amorphous metal alloy on a
reactor with the newly-added precursor metal-bearlng compound and
heat-treating this mixture at a temperature that will decompose the
precursor compound but that is below the crystallization temperatures
of the prior amorphous metal alloy and the enhanced amorphous metal
alloy that is to be synthesized. The newly-added precursor may be a
solid, liquid or gaseous material upon insertion into the reaction
vessel. As with the above-discussion, the decomposition of the
precursor material may occur in a partial or full vacuum, or under an
inert, reducing, or reactive atmosphere.
I 7
The solid state reaction that occurs to ally an intimate
mixture of elements may be viewed by examining the free energy of the
system. The intimate mixture of elements corresponds to a relatively
high free energy of the system. At about room temperature such
mixtures are generally canticle restricted to this state. Adding
energy to this system, as at the thermal decomposition temperature or
during subsequent heat-treatments, allows the components to begin to
inter-diffuse. The free energy of the system is lowered by an
increase in the entropy of mixing a decrease in the enthalpy due to
the formation of heteropolar bonds. The absolute minimuln in free
energy in these systems will occur far the equilibrium crystalline
alloys. For many alloy combinations, however, a local minimum in the
free energy can exist in an amorphous phase. For alloy combinations
such as these, the requirements for the formation of an amorphous
phase by a solid state reaction are that the intimate mixture of
components have a free energy higher than that of the amorphous phase
and that the diffusion process to form the alloy be performed at
temperatures sufficiently below the characteristic temperatures for
the formation of crystalline nuclei.
Amorphous metal alloys are generally characterized as having
high strengths and harnesses and so are quite resistant to
deformation. Typical amorphous shapes, such as ribbons and wires,
are formed simultaneously with the formation of the amorphous state.
These shapes exhibit the characteristics of an amorphous material.
However, attempts to form bulk amorphous shapes, that is, shapes
having significant thicknesses in all dimensions, have not been
satisfactory. These attempts generally include reducing an amorphous
metal alloy, such as a ribbon, to an amorphous powder by physical
means and then compacting the powder into a shape. Generally, the
compacted shape does not retain all the desirable traits of the
individual particles.
Whereas the process disclosed herein above teaches the
synthesis of amorphous metal alloy powders, it now becomes known, in
accordance with the invention claimed herein, that the intimate
mixture obtained as an intermediate in the formation of Applicants'
amorphous metal alloy powders may be effectively formed unto bulk
~3~3~'7
objects when at least one component of the intimate mixture is
Dakota. By ductile is meant a component that it mailable, pliant and
easily molded without cracking or fracturing. A typical Dakota
component will demonstrate deformation of at least ten percent under
a moderate load of between about Lowe psi and 5,000 psi. the
ductile component of the intimate mixture provides an infrastructure
that, when subjected to forming processes, deforms and binds the
other components of the alloy within a matrix.
The ductile component of the alloy originates in a precursor
compound that is used in the solid state reactions to form the
intimate mixture of the alloy components. Examples of ductile
components include pure metal elements, such as iron, nickel, copper,
cobalt and tantalum, and metal solid solutions. Preferably the
ductile component is a pure metal element.
To provide enhanced bonding strength and properties to the
formed amorphous metal alloy object, it is preferred that the ductile
component comprise from about lo atomic percent to about 95 atomic
percent of the amorphous metal alloy based on the total composition
of the amorphous metal alloy.
The intimate mixture of the components of the amorphous
metal alloy, which has not yet been heat-treated to induce the
amorphous state is subjected to a forming process. Forming processes
include well-known powder forming techniques such as cold-pressing,
hot-pressing, pressure less sistering, slipcast1ng, injection molding
and extrusion In accordance with this invent10n, the only
restriction on the forming process is that the process be performed
at a temperature below the crystallization temperature of the metal
alloy.
If the forming process includes the use of temperature above
ambient temperature, then the intimate mixture may be formed and made
amorphous simultaneously. If the forming process does not include
elevated temperatures, then a further step, heat-treating, will be
required to induce the amorphous state
Many intimate mixtures may be reactive with oxygen, and so,
may require forming and heat-treating processing which occurs in an
oxygen-free atmosphere such as an inert, reducing or reactive
11
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atmosphere or under vacuum conditions. A reactive atmosphere may be
provided that reacts with the bulk object so as to enhance the
formation of the amorphous alloy.
Amorphous metal alloy shapes generally have a density of
from about 10 percent to about 99 percent of theoretical. The
density may be controlled by the forming process so as meet a variety
of needs. Thus, the same amorphous metal alloy composition may be
formed into an amorphous metal alloy shape having a density between
about lo percent and about 90 percent of theoretical. It has also
been observed that the process of this invention permits the
attainment of a desired-density object at temperatures lower than
those necessary to achieve the same sistered state when the metal
alloy powder used to form the object is derived from the physical
reduction of a prior art, thin-film amorphous shape such as a ribbon.
The forming process may be used to provide an amorphous
metal alloy in a finished shape or in a solid shape amenable to
further machining. Thus, billies, rods, flat plates may be formed as
well as cylindrical shapes, toxoids and other intricate, finished
shapes.
The above-described processes for synthesizing amorphous
metal alloys are not hindered by the processing limitations of prior
art processes. The methods disclosed herein do not depend on
extremely high cooling rates or heat transfer properties, nor i; very
high temperature or very low vacuum equipment necessary. Further,
the processes of this invention provide or the synthesis of
substantially amorphous metal alloy powders, which amorphous alloy
powders may be pressed into desired shapes to form solid amorphous
alloy shapes. Alternatively, the methods disclosed herein provide an
intonate mixture of elements that may be formed into a desired shape
and, upon subsequent heat-treating, may be converted into a
substantially amorphous metal alloy shape. The method disclosed
herein does not depend on reducing an amorphous material to a powder
state and then recombining an amorphous powder but utilizes an
intimate mixture of the components of a metal alloy into a bulk shape
and thereafter, or concurrently, inducing the amorphous state by heat
treating at a temperature below the crystallization temperature of
12
the metal alloy. These bulk amorphous metal alloy shapes may find
new and useful applications, since such shapes have not teen
conveniently fabricated by any other techniques.
EXAMPLE
The following examples more thoroughly illustrate the
present invention and are not intended in any way to be limitative
thereof. Each of the following examples describes the
co-decomposition of organometallic compounds to yield amorphous metal
alloy powders.
Example 1
This example demonstrates the formation of an amorphous
iron-molybdenum composition.
Equimolar amounts of about 2 Molly each of
cyclopentadienyliron dicarbonyl diver [C5H5Fe(C0~]2and
cyclopentadienylmolybdenum tricarbonyl diver [C5H5Mo~C03)]2
were disposed in a stainless steel bomb reactor. The reactor was
purged with argon and sealed under an argon atmosphere. the bomb
reactor was then heated to a temperature of about 300C for about 24
hours. The decomposition temperature of cyclopentadienyliron
dicarbonyl diver is about 195C, and the decomposition temperature of
cyclopentadienylmolybdenum tricarbonyl diver is about 180C.
After cooling to about 20C, the reactor was opened and a
black-colored solid, in powder form, was removed therefrom. The
powder was washed with tetrahydrofuran to remove any organic-soluble
materials, then dried at a temperature of about 60C under vacuum.
The powder was next divided into four fractions, a first
fraction was set aside for later analysis, and the other three
fractions were Further treated in the following manner; one fraction
was heat-treated at about 270C under vacuum for about 168 hours,
another fraction was heat-treated at about 325C under vacuum for
about 168 hours, and still another fraction was heat-treated at about
800C under vacuum for about 10 minutes.
X-ray diffraction data indicated that the powder removed
from the bomb reactor after co-decomposition of the precursor
materials comprised an amorphous iron-molybdenum alloy having an
approximate composition of Fume. The fractions of the powder
13
that were heat-treated at about 270C and about 325C were also
found to comprise an amorphous lron-molybdenum alloy of approximate
composition Foe, as indicated by x-ray diffraction, but the
fraction of the powder that was heat-treated at about 800C was
crystalline.
Differential scanning calorimetry was implemented to
determine that the amorphous alloy powder fractions had glass
transition temperatures of about 325~C and crystallization
temperatures of about 420C. Mossbauer Effect Spectra of the
amorphous powder fractions indicated that these amorphous
iron-molybdenum alloy powders have internal magnetic fields and
magnetic moments similar to other iron-containing amorphous alloys.
Amorphous iron-molybdenum alloy compositions have not been
reported as formed by any other method except sputtering, which
method cannot synthesize the amorphous alloy in powder form.
Example 2
This example demonstrates the formation of an amorphous
iron-molybdenum composition using alternative precursor
organometallic compounds.
Equimolar amounts of iron pentacarbonyl (Fake and
molybdenum carbonyl (Mohawk) could be sealed under an inert
atmosphere such as an argon atmosphere or under a vacuum in a bomb
reactor and heated to about 270~C for about 120 hours to thermally
decompose about all of the precursor compounds and to alloy the
reactant product elements. the decomposition temperature of iron
pentacarbonyl is about 150C, and the decomposition temperature of
molybdenum carbonyl is about 150C.
The resultant solid, powder material that is obtained by
this decomposition can be confirmed by x-ray diffraction to be
amorphous iron-molybdenum alloy. The approximate composition will be
amorphous Fume.
,,
I k7
This example demonstrates the formation of an amorphous
iron-molybdenum nitrogen composition.
Equimolar amounts of iron pentacarbonyl fake) and
mo91ybdenum carbonyl (Mohawk) may be disposed in a reactor and
sealed under an atmosphere of ammonia. The reactor could then be
heated to a temperature above the decomposition temperatures of iron
pentacarbonyl and molybdenum carbonyl, which it above about 270~C for
a period of time that would insure decomposition of the reactant
materials and alloying of the component elements.
The product that would be obtained as a solid powder
material will be an amorphous iron-molybdenum-nitrogen alloy of
approximate composition Famine the nitrogen having been
derived from the ammonia atmosphere under which the solid products
were sealed prior to heating.
Example 4
This example describes the formation of an amorphous
iron-chromium-molybdenum composition.
Top following three organometallic precursor materials could
be disposed in a bomb reactor in about the following molar ratios:
1.0 mow equivalent iron dodecarbonyl (Fake), 0.5 mow
equivalent chromium carbonyl (Crook), and 3 mow equivalents
molybdenum carbonyl (Mohawk). the decomposition temperature of
Ron dodecarbonyl is about 140C. The decomposition temperature of
chromium carbonyl is about 200C. The decomposition temperature of
molybdenum carbonyl is about 150C.
The reactor may then be sealed under an inert atmosphere and
heated to a temperature above about 270C for a period of lime
suPPicient to decompose the precursor compounds and to alloy the
elements of the amorphous composition.
The solid, powder material that is obtained from this
thermal decomposition will be an amorphous iron-chromium-molybdenum
material of approximate composition Faker Moe.
Example 5 1~33~47
Example q above could also have been performed under an
atmosphere other than an inert atmosphere so as to modify the product
amorphous metal alloy.
The inert atmosphere of Example 4 may be replaced with a
phosphorus atmosphere obtained by disposing solid elemental
phosphorus, such as red phosphorus in the reactor with the other
precursor compounds and sealing the reactor under a vacuum. At
elevated temperatures, the phosphorus would vaporize producing a
phosphorus atmosphere during the decomposition of the other precursor
compounds. The resultant amorphous metal alloy from the thermal
decomposition reaction may have an approximate composition of
3 0.5 3-
Example 6
This example demonstrate the formation of an amorphous
tungsten-nickel-carbon capstone.
Precursor materials, mes~tylene tungsten tricarbonyl
(CgH12W(CO)3) and bis(triphenylphosphine) nickel dicarbonyl
[)(C6H5)3P]2Ni(CO)2, may be disposed in a bomb reactor in a
molar ratio of about 1:2. The decomposition temperature of
mesitylene tungsten tricarbonyl is about 165C, and the decomposition
temperature of bis(triphenylphosphine) nickel dicarbonyl is about
215C. The reactor may be sealed under an inert atmosphere such as
an argon atmosphere and then heated to a temperature above about
215C for a time long enough to insure that the precursor compounds
have substantially decomposed and alloyed.
A solid, powder material would result that is an amorphous
tungsten-nickel-carbon-phoszphorus maternal having an approximate
composition of Wink UP.
~Ej~m~le 7
The formation of an amorphous cobalt rhenium composition is
described in this example.
The following two organometallic precursor materials may be
disposed in a bomb reactor in about the following molar ratios: 1
mol. rhenium carbonyl (Wreck) and 2 mows cobalt carbonyl
(C02(CO)8). The reactor may then be sealed under an inert
16
atmosphere, such as an argon atmosphere and heated to bout at least
170C for a time sufficient to thermally decompose the precursor
compounds. the decomposition temperature of rhenium carbonyl is
about 170C. The decomposition temperature so cobalt carbonyl is
about 55C. The resultant solid, powder material that is obtained by
this decomposition will be an amorphous alloy of cobalt rhenium. The
approximate composition will be amorphous Core.
Example 8
The formation of an amorphous tungsten-cobalt-iron
composition is described in this example.
The following organometallic precursor materials may be
disposed in a bomb reactor in about the following molar ratios: 1
mow equivalent tungsten carbonyl (WACO), 1 mow equivalent cobalt
carbonyl (Cook), and 2 mows equivalents iron nonacrbonyl
(Fake). Tungsten carbonyl has a decomposition temperature of
about 170C. Cobalt carbonyl has a decompos~tlon temperature of
about 55C. Iron nonacrbonyl has a decomposition temperature of
about 100C.
The reactor may be sealed under an inert atmosphere and
heated to a temperature above about 270~C so as to substantially
thermally decompose the precursor compounds and to alloy the product
elements.
The powder removed from the bomb reactor after the
co-decomposit~on of the precursor materials will comprise an
amorphous tungsten-cobalt-iron composition of approximately
2 4
Example 9
This example demonstrates the formation of an amorphous
chromium-iron-nickel-boron composition synthesized by adding a
chromium-hearing precursor compound to an amorphous iron-nickel-boron
alloy.
Chromium carbonyl (Crook) was mixed with a substantially
amorphous metal alloy of iron-nickel-boron, having an approximate
composition Fe2Ni2B, in a molar ratio of about 1:2 and were then
disposed in a bomb reactor, evacuated and sealed. Chromium carbonyl
thermally decompose at about 200~C. The crystallization temperature
1~33~7
of the amorphous Fe2Ni2B alloy is abut 410C, its glass
transition temperature is about 330C.
The sealed reactor was heated to about 250C and maintained
t about that temperature for about 120 hours. Upon cooling and
opening the reactor and examining its components, no chromium
carbonyl was found to be present. However, x-ray diffraction
analysis determined that the powder that was removed from the reactor
after this heat-treating was amorphous, having an approximate
composition of Cry 5Fe2Ni2B. Thus, the process disclosed
herein may include the enhancement of an amorphous metal alloy by
further decomposing a metal-bearing precursor compound in the
presence of an amorphous metal alloy whereby the metal in the
precursor compound is incorporated into the alloy, and which alloy
remains substantially amorphous.
The above-described examples demonstrate the formation of
amorphous metal alloy compositions by decomposition of precursor
metal-bearing materials. The formation of such amorphous materials
could only be obtained previously by processes that utilize high
temperature, energy intensive equipment. In addition, the novel
processes described herein above produce amorphous metal alloy
powders, whereas prior art processes yield the amorphous material
only in a solid, thin-film or ribbon-like form which must first be
reduced to a powder if it is to be formed into a solid shape.
This example demonstrates the formation of a solid shape
having amorphous characteristics and an approximate composition ox
Phony 2B .
Exam e 10
In this Example, an intimate mixture of the components of
the amorphous metal alloy was obtained by a chemical reduction
process.
Equimolar amounts of iron chloride, Focal, and
nickel chloride, Nucleus, were dissolved in distilled water to
form a reaction solution. This solution was degassed with argon so
as to purge oxygen from the solution. An argon-degassed solution of
sodium bordered, Nub, was then added drops to the reaction
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aye
solution. The solution was stirred for about sixteen hours to insure
that the reaction had gone to completion.
A black precipitate was recovered from the solution and
dried at about 60C under vacuum. This precipitate was an intimate
mixture of the components of the metal alloy to be formed. The
intimate mixture comprised iron metal and nickel bride. Thy pure
iron metal is the ductile component of the mixture.
This powder mixture was kept under an argon atmosphere to
prevent oxidation and compacted into a disc having a diameter of
about 1 cm and a thickness of about 0 1 cm at a pressure of about
1~,000 psi and at about 20C. The disc was sealed in an evacuated
glass tube and heat treated at about 250C for about 312 hours.
X-ray diffraction analysis revealed that the resultant disc
was a solid amorphous metal alloy having a composition of about
Fe2Ni2B. This disc had a density that was about 98 percent of
theoretical.
The formation of amorphous metal alloy shapes could only be
formed previously by first reducing an already-amorphous material
into a powder and then compacting the powder. Such a process is not
desirable since it inherently is energy 1ntensiYe and cannot reliably
produce consistent, homogeneous amorphous shapes. The disadvantages
of the prior art are removed with the 3bove-described process.
The selection of precursor materials, decomposition
temperatures, heat-treating temperatures and other reactant
conditions can be determined from the proceeding Specification
without departing from the spirit of the Invention herein disclosed
and described. The scope of the invention is intended to include
modifications and variations that fall within the scope of the
appended claims.
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