Note: Descriptions are shown in the official language in which they were submitted.
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Plewes, .J. T. 7
Background of the Invention
1. Field of the Invention
-
The inven-tion is concerned with copper based
alloys having predominantly spinodal structure.
2. ~ n of the _rlor Art
Alloys containing copper, nickel, and tin have
been proposed as economical substitutes for
copper-beryllium and phosphor-bronze alloys in the
manufacture of shaped articles such as wire, wire
connectors, springs, and relay elements~ ~mong alloy
properties on which such use is based are high strength,
good formability, corrosion resistance, solderability, and
electrical conductivity. Cu-Ni^Sn alloys exhibiting
desirable combinations of proper~ies are disclosed in U.S~
patent No~ 3,937,638, U.S. patent ~o. 4,052,204 and U.S.
patent No. 4,090,890, all in the name of J. T. Plewes~
U. SO patent No. 3,937,638 discloses a treatment
of a Cu-Ni-Sn cast ingot which involves homogenizing,
cold working, and aging and which leads to a
20predominantly spinodal structure in the treated alloy.
For example in the case of an alloy containing seven
percent Ni, eight percent Sn, and remainder copper, an
exemplary method calls for homogenizing the cast ingot,
cold working to achieve 9~ percent area reduction, and
aging for eight seconds at a temperature of 425 degrees
C. The resulting article has 0.01 percent yield strength
of 173,000 psi and ductility o~ 47 percent area reduction
to fracture~
U.S. Patent No. 4,052,204 discloses
30 quaternary alloys containing not only Cu, Ni, and Sn, but
also at least one additional element selected from among
-- 1 --
Plewes, J. T. 7
the elements Fe, Zn, ~n, Zr, Nb, Cr, Al, and Mg. A
predominantly spinodal structure is produced in these
alloys by a treatment of homogenizing, cold working, and
aging analogous to the treatment disclosed in U. S.
patent No. 3,937,538.
U.S. Patent No. 4,090,890 discloses cold
rolled and aged strip material made of alloys having a
composition similar to the composition of alloys disclosed
in U. S. patent No. 3,937,638 and U.S. patent No.
10 4,052,204 and having not only high strength, but also
essentially isotropic formability. As a consequence, such
strip material is particularly suited for the manufacture
of articles which require bending of the strip in
directions having a substantial component perpendicular to
the rolling direction.
Cu7Ni--Sn alloys and their properties are a subject
also of the following papers: L. H. Schwartz, S. ~ahajan,
and J. T. Plewes, "Spinodal ~ecomposition in a Cu~g wt%
Ni 6 wt% Sn Alloyi', Acta Metallurgica, Vol. 22, May 1974,
20pp. 601-509; L. H. Schwartz and J. T. Plewes, "Spinodal
Decomposition in Cu~9wt% Ni~6wt% Sn'II. A Critical
Examination of Mechanical Strength of Spinodal Alloys",
Acta Metallurgica, Vol. 22, July 1974, pp. 911~921; John
T. Plewes, "Spinodal Cu~Ni 5n Alloys are Strong and
Superductile", Metal_P_~ress, July 1974, pp. 46~50; J. T.
Plewes, "High~Strength Cu~Ni Sn Alloys by
Thermo~mechanical Processing", Metallur~al Transactions
A, Vol. 6A, March 1975, pp. 537~544.
The achievement of good strength and bend
30 properties in copper based alloys containing Ni and Sn is
an object also of the method disclosed in U. S. patent
No. 3,941,620, M. J. Pryor et a]., "Method of Processing
Copper Base Alloys". Pryor discloses a method for treating
an ingot by homogenizing7 cold rolling, aging, and again
cold rolling.
Summary of the Invention
In accordance with an aspect of the invention
there is provided a method for manufacturing a body of a
predominantly spinodal alloy by a treatment of an initial
body which, in an amount of at least 95 percent by weight,
consists of Cu, Ni, .Sn and at least one additional element,
wherein Ni is present in an amount of from 3-20 weight
percent, Sn is present in an amount of from 3.5 to 10 weight
percent at 3 percent Ni to 3.5 to 12 weight percent at 20
percent Ni, and said additional element is selected from Mo
in an amount of from 0.02-0.07 weight percent at 3 percent
Ni to 0.05-0.1 weight percent at 20 percent Ni, Nb ln an
amount of from 0.05-0.3 weight percent at 3 percent Ni to
0.08-0.35 weight percent at 20 percent Mi, Ta in an amount
of from 0.02-0.1 weight percent at 3 percent Ni to 0.05-0.3
weight percent at 20 percent Ni, V in an amount of from
0.1-0.5 weight percent at 3 percent Ni to 0.02-0.5 weight
percent at 20 percent Ni, and Fe in an amoun-t of from 1-5
weight percent at 3 percent Ni to 2-7 weight percent at 20
percent Ni, wherein said treatment is conducted so as to
terminate with the steps of short term low temperature
annealing so as to form a solid solution of the Cu-Ni-Sn
component of the alloy and to precipitate the said at least
one additional element, rapid ~uenching and aging, carried
out in the order stated, and, optionally, including in the
said treatment a cold working in an amount of less than 25
percent area reduction to be conducted prior to the said
aging.
It has been discovered that in copper based alloys
containing from 3-20 weight percent Ni, from 3.5-10 weight
percent Sn at 3 percent Ni and from 3.5-12 weight percent Sn
at 20 percent Ni, an element selected from the group
consisting of Mo, Nb, Ta, V, and Fe, and remainder copper, a
predominantly spinodal structure can be developed by a
treatment of annealing, ~uenchingl and aging. Since the
treatment does not require cold deformation, such alloys are
equally suited Eor the manufacture of articles by hot
working, cold working, casting, forging, extruding, hot
pressing, or cold working. Resulting article are strong,
ductile, and have isotropic formability.
Brief Description of the Drawing
FIG. 1 is a diagram which shows combinations of
yield strength on the ordinate and fracture elongation on
the abscissa realized in two prior art alloys (designated 1
and 2) and four alloys of the invention (designated 3, 4, 5
and 6).
FIG. 2 is a diagram which shows combinations of
yield strength on the ordinate and elongation on the
abscissa of ~ Cu-15Ni-8Sn-0.2Nb alloy which was annealed and
aged by various amounts.
Detailed Description
FIG. 1 shows curves 1 and 2 corresponding to prior
art al]oys Cu - ]5 percent Ni - 8 percent Sn and Cu
- 3a -
Ple~es, J. T. 7
- 2 percent Be, and curves 3, 4, 5 and ~ corresponding,
respectively, to new alloys Cu - 15 percent Ni - 8 percent
Sn - 0.07 percent Mo, Cu - 15 percent Ni - 8 percent Sn -
0.02 percent Ta, Cu - 15 percent Ni - 8 percent Sn - 0.18
percent Nb, and Cu - 15 percent Ni - ~ percent Sn - 0.38
percent V. Cu-Be alloy is as commercially available.
Cu-Ni-Sn alloys have been annealed a~ 825 degrees C~ for
one hour, water quenched, and aged at 400 degrees C. by
varying amounts, longer aging times corresponding to
10 higher levels of yield strength an~ shorter aging times
corresponding to higher levels of fracture elongation.
FIG. 1 illustrates the superior strength and ductility of
the new a11QYS as compared with prior art alloys.
~ IG. 2 shows properties of 0.03" (0.076 cm.~ wire
of a Cu - 15 percent Ni - 8 percent Sn - 0.2 percent Nb
alloy. Solid curves correspond to properties of a wire
which was annealed at a temperature of 825 degrees C. for
periods of from 7-20 minutes, 1 hour, 4 hours, and 17
hours, followed by quenching and aging at ~00 degrees C.
20 for 1 hour~ Dashed curves correspond to properties of a
wire which was annealed at 900 degrees C. for periods of 1
hour, 4 hours, and 17 hours, followed by quenching and
aging at 400 degrees C. for 1 hour~ FIG. 2 illustrates
the influence of anneal temperature on ultimate properties
of the alloy and, for fixed anneal temperature, the
influence of anneal time on such properties. Apparent, in
view of FIG. 2, is the desirability of short anneal times
and low anneal temperatures.
Alloys of the invention contain 3-20 weight
30 percent Ni, 3.5-10 weight percent Sn at 3 percent Ni and
3.5-12 weight percent Sn at 20 percent Ni. Limits on Sn
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Plewes, J. T. 7
contents for intermediary levels of ~i may be obtained by
linear interpolation between limits at 3 percent
and 20 percent Ni.
While the preparation of a melt of a Cu-Ni-Sn Fe
alloy of the invention may proceed by customary
metallurgical practice, special care is required in the
preparation of melts containing refractory elements Mo
Nb, Ta, or V.
Preparation of such latter melts may proceed~ for
10 example, as follows. Cu and Ni or a Cu-Ni alloy are
melted in air at a temperature in the vicinity of 1300
degrees C. resulting in a melt high in oxygen and low in
hydrogen contents. To reduce oxygen contents a cover oE
dry graphite chips is placed on the melt.
Simultaneously, an inert gas such as argon is bubbled
through the melt for a period of about one half hour to
prevent hydrogen contents of the melt from increasing.
Sn is added while bubbling of the inert gas is
maintained, and the temperature of the Cu~Ni~Sn melt is
20 reduced to the vicinity of 1250 degrees C. It has been
found beneficial to add a small amount of Mn to the melt
at this point to tie up residual sulfur. It is also
beneficial at this point to plunge a small amount of Mg
into the melt as a pre~deoxidant. Amounts of Mn in the
range oE 0.1-0.3 percent and ~g in the range of 0.05:0.1
percent are generally adequate for such purposes, Mg
being added preferably in the form of CuMg alloy. Mo,
Nb, Ta, or V is now plunged into the melt, preferably as
a eutectic mixture with Ni to facilitate mixing~ Lo~
30 meltin~ point eutectic compositions are as follows:
-- 5
.4, Il,
~le~es, J T. 7
Ni-50 percent ~b, Ni-35 percent Ta, Ni-47 percent ~,
Ni-46 percent Mo.
rhe process described above for adding refractory
metals Mo, ~b, Ta, or V to a melt of Cu, Ni, and Sn has
been found to have a yield of 60-80 percent. To ensure
the presence in the final alloy of a desired percentage
of the refractory metal, a correspondingly greater amount
of starting material has to be added initially.
The addition of Mg to the melt as called for
10above may result in residual amounts of Mg to be present
in the alloy. Such presence does not materially diminish
optimal alloy properties and is tolerable in amounts of
up to 0.1 percent Mg. Mn may be tolerated in even larger
amounts and may be intentionally added in amounts up to 5
percent/ e.g., as a less expensive substitute for copper.
Similarly, amounts of up to 5 percent gn may replace Cu
without undue degradation of alloy preperties. Other
impurities, such as may be present in commercially
available alloy ingredients, are tolerable in amounts of
20 up to 0.2 percent Co, 0.1 percent Al, 0~01 percent P,
0.05 percent Si, 0.005 percent Pb. ~xygen contents
should be kept below 100 ppm to prevent the formation of
refractory metal oxides. Combined amounts of impurities
in the alloy should preferably not exceed 5 weight
percent.
An article of the invention may be shaped as cast
or a cast ingot may undergo processing and shaping at
temperatures at or above the recrystallization
temperature by means such a forging, extruding, hot
30 working, or hot pressing. The shaped article is annealed
at a temperature in a range which depends on Ni and Sn
- 6 _
Plewes, J. T. 7
contents of the alloy as shown in Table 1 for four
exemplary alloys. In general, for fixed amounts of Ni,
the upper limit on anneal temperature decreases with
increasing amounts of Sn and the lower limit on anneal
temperature increases with increasing amounts of Sn.
Conversely, for fixed amounts of Sn, both the upper and
the lower limit on anneal temperature increase with
increasing amounts of Ni. To prevent coarsening of the
dis~ribution, annealing temperatures are preferably
10 chosen close to ~he lower limit of the permissible range
as shown in Table 1 for exemplary combinations of Cu,
Ni, and Sn. Moreover, as illustrated in FIG. 2,
annealing times should preferably not exceed four hours.
Annealing times as short as 7-~0 minutes may be
sufficient for small articles. Such annealing causes
formation of a solid solution of the Cu-Ni-Sn component
of the alloy and, simultaneously~ precipitation of the
additional element at the grain boundaries as well as
within the matrix.
After annealing, the article is water or brine
quenched and aged at a temperature in the range of from
300 degrees C. to 475 degrees C. An aging temperature in
the range of 375-425 degrees C. may be considered
typical; however, aging temperature may be adjusted to
compensate for longer or shorter aging time as may be
practical depending on the size and shape of the article.
Specifically, in the interest of uniform internal
temperature distribution, bulky articles are preferably
aged for a longer perlod of time while wire and strip
30 material may be aged, e.g., in a continuous process, Eor
a shorter period of time. An increase in aging time by a
-- 7
3~ .
Plewes, J. T. 7
factor of ten typically corresponds to a decrease in
aging temperature by about 50 degrees C. and conversely.
However, aging time must not exceed approximately 475
degrees C, higher temperatures beiny conducive to an
undesirable embrittling nucleation-and-growth
transformation. It is a characteristic feature of the
disclosed method that no use need be made of cold working
to develop a spinodal structure and that, consequently,
an article of manufacture according to the invention may
be shaped as cast, forged, hot worked, hot pressed, or
e~truded, i~e., shaped at temperatures at or above the
recrystallization temperature of the alloy. While
processing involving no cold work is a preferred mode of
manufacturing articles according to the invention, a step
of cold working prior to aging to further shape an
article by any desired amount is not precluded. The
presence of an additional element selected from the group
consisting of Mo, Nb, Ta, V, and Fe in the alloy has the
additional beneficial effect that, in applications in
29 which strength o~ the shaped article is a primary
requirement, higher levels of strength are achieved for a
given amount of cold work compared with strength achieved
in a correspondin~ Cu-I~i Sn alloy not containing such
additional element. Amounts of cold work oE less than 25
percent area reduction or even less than 20 percent or 15
percent area reduction are beneficial in this context.
In the event cold working is utilized r customary
duplexing of cold working and aging is not precluded.
Specifically, instead of terminating in se~uential
30annealing, quenching, cold working, and aging, such
treatment may terminate, e.g., in the sequential steps of
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Plewes, J T. 7
annealing, quenching, cold working, aging, quenching,
cold working, aging. Still more eleborate methods are
also within the scope of the invention provided they
comprise, in the order stated, the steps of annealing,
quenching, and aging, which order is implied throuyhout
this disclosure.
It has been ascertained that amounts of Mo, Nb,
Ta, V, or Fe which are desirable for the purpose of the
invention lie within relatively narrow and well-defined
ranges outside of which distinctly inferior properties
are realized. Specific limits for an alloy containing 3
percent Ni are 0.02-0.07 weight percent Mo, ~.05-0.3
weight percent Nb, 0.02-~.1 weight percent Ta, ~.10-0.5
weight percent V, or 1-5 weight percent Fe. For an
alloy containing 20 percent Ni, corresponding limits are
0.05-0.1 weight percent Mo, 0.08-0.35 weight percent Nb,
0.05-0.3 weight percent Ta, 0.2-0.5 weight percent V, or
2-7 weight percent Fe. For intermediary amounts of
nickel, limits for Mo, Nb, Ta, and V may be obtained by
20 linear interpolation between limits at 3 percent and at
2~ percent Ni. Amounts below the given lower limits are
less desirable because of insufficient precipitation of
the additional element during annealing, amounts
exceeding the given upper limits favor the presence of
Ni-refractory intermetallics which may cause reduced
ductility. For the purpose of the invention, additives Mo,
Nb, Ta, V, and Fe may also be used in combination in
which case at least one o~ them should preferably be
present in an amount within the stated limits.
Examples 1 through 18 are shown in Table 2.
Melts containing refractory elements Mo, Nb, Ta, or V
_ g _
Plewes, J. T. 7
were prepared by the method described a~ove. Cast ingots
were cold rolled by an amount o~ 50 percent area
reduction prior to annealing, quenching, and aging.
Annealing temperature was 825 degrees C. for examples
1-10, 850 degrees C. for examples 11-14, and 900 degrees ~;
C. for examples 15-18.
- 10 - '
~A~LE 1 Plewes, J. T. 7
Annealin~ Ten~per~ture T:~e~rees ~,
,0 Ni ~ Sn P~n~e rel erred ~an~e
~25 ~ 975 652 - 700
~ 67 5 - ~6û 67 5 - 7 50
~; 740 - 975 75~ - 800
9 825 - 900 82 ~ - 850
77~ - 975 775 - 825
820 - 900 820 - 8~0
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