US3297497A

US3297497A - Copper base alloy

Info

Publication number: US3297497A
Application number: US341121A
Authority: US
Inventors: Jr George H Eichelman; Broverman Irwin
Original assignee: Olin Corp
Current assignee: Olin Corp
Priority date: 1964-01-29
Filing date: 1964-01-29
Publication date: 1967-01-10
Anticipated expiration: 1984-01-10

Description

3,297,497 COPPER BASE ALLOY George H. Eichelman, Jr., and Irwin Broverman, Cheshire, Conn., assignors to Olin Mathieson Chemical Corporation, a corporation of Virginia No Drawing. Filed Jan. 29, 1964, Ser. No. 341,121 8 Claims. (Cl. 14832.5)

The present invention relates to improved aluminumbronze alloys and to the preparation thereof. More particularly, the present invention resides in novel and inexpensively prepared copper base alloys containing from 9.0 to 11.8 percent aluminum, from 0.05 to 5.0 percent of at least one additional element having a solid solubility in copper of less than 4.0 percent and which forms one or more intermetallic compounds with aluminum, with the total quantity of said additional elements being less than 10.0 percent and preferably less than 5.0 percent, and the balance essentially copper. The additional element is preferably one or more of the following elements: iron; chromium; titanium; zirconium; molybdenum; columbium; and vanadium. The foregoing alloys are prepared in such a manner as to be characterized by physical properties heretofore unattainable in alloys of this type. For example, the novel alloys of the present invention attain surprisingly high tensile strengths combined with high ductility. This combination of properties provides superior toughness and formability. In addition, the novel alloys of the present invention have reasonably good electrical conductivity plus good brazability, solderability, Weldability, corrosion resistance, stress corrosion resistance, and fatigue strength.

I The novel and inexpensively prepared alloys of the present invention readily attain a combination of strength and ductility heretofore unattainable in these alloys, for example, tensile strengths ranging from 120,000 to 160,000 p.s.i. and yield strengths ranging from 60,000 to 80,000 p.s.i. at 0.2 percent offset in combination with elongations ranging from 12 to 9 percent. In addition, electrical conductivity values ranging from 10 to 16 percent IACS are attained. Properties of this type approximate those provided by the relatively expensive beryllium-copper alloys. A lower cost of series of alloys exhibiting properties similar to the reltaively expensive beryllium-copper alloys, such as provided in accordance with the present invention, would therefore, find wide application in a Wide variety of fields, as a replacement for beryllium-copper in the manufacture of electrical springs, contacts, and diaphragms. In fact, considerable effort has been expended in the art, heretofore unsuccessful, to develop such a lower cost substitute for beryllium-copper.

Alloys exhibiting the foregoing properties would also tend to replace lower cost copper base alloys having lower strengths. In addition, these alloys would tend to replace a variety of other copper base alloys which are in a lower price range than beryllium-copper, e.g., Phosphor-bronze.

The alloys of the present invention are extremely versatile and have a wide variety of other uses exemplificative of which are: corrosion resistant parts, such as condenser tubes and valves; metal bellows; heat resistant parts in which resistance to corrosion at high temperature is required, such as parts for internal combustion engines; wear resistant parts; and metal forming dies.

Accordingly, it is an object of the present invention to provide new and improved aluminum-bronze alloys and methods for the preparation thereof.

It is a further object of the present invention to provide an alloy as aforesaid which is characterized by physical properties heretofore unattainable in alloys of this type, and especially possessing a greatly improved combination of yield strength, tensile strength and ductility.

It is a still further object of the present invention to provide an alloy as aforesaid which attains these greatly improved physical properties without degradation of other properties so desirable in alloys of this type.

It is a still further object of the present invention to provide an alloy and process as above conveniently, expenditiously and at reasonable cost.

Further objects and advantages of the present invention will appear hereinafter.

In accordance with the present invention it has noW been found that the foregoing objects and advantages of the present invention may be readily accomplished. The process of the present invention comprises: hot working at a temperature of from -1850 F. to 1000 F. a copper base alloy containing from 9.0 to 11.8 percent aluminum, from 0.05 to 5.0 percent of at least one additional element having a solid solubility in copper of less than 4.0 percent and which forms at least one intermetallic compound with aluminum, with the total quantity of said additional elements added being less than 10.0 percent and preferably less than 5.0 percent, and the balance essentially copper; and cold Working said alloy at a temperature below 500 F.

In the improved aluminum-bronze alloy of the present invention, the additional element referred to above which has a solid solubility in copper of less than 4.0 percent and which forms one or more intermetallic compounds with aluminum, is preferably selected from the group consisting of the following elements in the following preferred amounts: iron from 2.0 to 5.0 percent; chromium from 0.4 to 2.0 percent; titanium from 0.4 to 2.0 percent; zirconium from 0.05 to 0.2 percent; molybdenum from 0.4 to 2.0 percent; columbium from 0.4 to 2.0 percent; vanadium from 0.4 to 2.0 percent; and mixtures thereof. In addition, the improved alloy of the present invention has a metallographic structure containing from 5 to percent beta phase and the remainder alpha phase. The micro-structure of the present alloy contains a dispersion which likely consists in part of one or more intermetallic compounds which is formed between aluminum and each of the additional elements of the present invention. The present alloy also has a uniformly fine metallographic grain structure with a grain size less than 0.065 mm. and generally less than 0.040 mm.

In co-pending application Serial No. 328,184, filed December 5, 1963 by George H. Eichelman Jr., and Irwin Broverman, there is described a novel aluminum-bronze alloy containing from 9.0 to 11.8 percent aluminum and the balance essentially copper. The improved alloy of said co-pending application has a metallographic structure containing from 5 to 95 percent beta phase and remainder alpha phase. In addition, the alloy of said copending application has a uniformly fine metallographic grain structure with a grain size less than 0.065 mm. The alloys of said co-pending application readily attain a combination of strength and ductility heretofore unattainable in alloys of this type.

The improved alloys of the present invention represent a still further improvement over the alloys of said co-pending application. This improvement is attained by the addition of from 0.05 to 5.0 percent of at least one additional element having a solid solubility in copper of less than 4.0 percent and which forms at least one interrnetallic compound with aluminium. The additional element is preferably selected from the following group of elements, although the present invention is not necessarily limited to these elements, iron, chromium, titanium, zirconium, molybdenum, columbium, vanadium and mixtures thereof in the preferred amounts set forth hereinabove. The additional element or elements serve to inhibit the grain growth so that it is possible to obtain a still finer grain size than is attained in accordance with the teaching of said co-pending application. This further improvement in grain size is due to the formation of the abovementioned dispersion, including the intermetallic compound or compounds. The overall effect is to develop even higher strength levels in the present alloys than is attained in accordance with the teaching of said co-pending application for comparable ductilities.

The alloys of the present invention contain from 9.0 to 11.8 percent aluminum. The aluminum content must critically 'be within the aforementioned range and preferably is within the more limited range 9.4 to 10.4 percent aluminum and optimally is between 9.8 to 10.0 percent aluminum. In addition, the alloy of the present invention must critically contain from 0.05 to 5.0 percent of at least one additional element as defined above, with the following being preferred: iron; chromium; titanium; zirconium; molybdenum; columbium; and vanadium. Iron is preferably present in an amount of from 2 to percent and optimally from 3 to 4 percent. Chromium, titanium, molybdenum, columbium, and vanadium are each preferably present in an amount of from 0.4 to 2.0 percent, and optimally in an amount of from 1 to 2 percent. Zirconium is preferably present in an amount of from 0.05 to 0.2 percent and optimally from 0.1 to 0.2 percent.

The additional element must, as discussed above, have limited solid solubility in copper and be an intermetallic compound former with aluminum. Preferably, the additional element should be a strong intermetallic compound former with aluminum and should in fact preferentially form intermetallic compounds with aluminum. In addition, the additional element and/or intermetallic compounds formed should preferably form a dispersion in copper with limited solid solubility at temperatures up to 1800 F. The presence of this dispersion acts to prevent grain growth at high heat treatment temperatures.

The remainder or balance of the alloy is essentially copper, i.e., the alloy may contain incidental impurities or other materials which do not materially degrade the physical characteristics of the alloy. Examples of such elements which can be present include tin, zinc, lead, nickel, silicon, silver, phosphorus, magnesuim, antimony, bismuth, and arsenic.

The alloy of the present invention is prepared in accordance with the foregoing critical combination of steps to provide the surprisingly improved composition of the present invention.

The first critical step in the process of the present invention is the hot working step in the aforementioned critical temperature range. Preparatory to the hot working step the alloy may naturally be melted and cast in a suitable 'bar or ingot form using conventional practices to insure compositional and structural homogeneity. For example, cathode copper may be induction melted under a charcoal cover or suitable salt flux. High purity or commercial aluminum in the requisite quantity may then be added and the melt thoroughly stirred to insure adequate mixing. The additional elements may be added in the same manner, that is, high purity or commercial iron, chromium, titanium, zirconium, molybdenum, columbium, and/ or vanadium may be added in the desired amount and the melt thoroughly stirred to insure adequate mixing. The molten charge may then be cast by any commercial method which will insure a sound cast structure that is essentially free from entrained aluminum oxide.

The foregoing is, of course, intended to be illustrative and not restrictive. It is only necessary that there be provided a homogeneous, sound and clean aluminum-bronze alloy satisfying the foregoing compositional requirements.

The resultant as-cast structure of the alloys of the present invention contains a dispersion distributed throughout the alpha, beta matrix as discussed above. This dispersion contributes to a finer as-cast grain structure than the 'binary alloys of the above-identified co-pending application Serial No. 328,184.

As stated above, the alloy is hot worked in the foregoing temperature range. The term hot working is employed in its conventional sense, although, in accordance with the present invention hot rolling is the preferred operation and the present process will be described in more detail with reference to this preferred mode of operation. Naturally, other methods of hot working will readily suggest themselves to those skilled in the art, e.g., forging and extrusion.

The manner of bringing the material into the hot rolling temperature range is not critical and any convenient heating rate or method may be employed.

The temperature of hot rolling is, as stated above, from l850 to 1000 F., with it being preferred to utilize a narrower temperature range of from 1650 F. to 1000 F.

In the process of the present invention, the as-cast material may simply be heated up to the starting temperature. The time at temperature is not critical and generally the casting is simply held long enough to insure uniformity of temperature. We then may hot roll directly from this temperature. During rolling of the ingot, some cooling occurs through natural causes. It is not necessary to maintain the ingot at any one starting temperature. In fact, it is preferred not to maintain the ingot at any one starting temperature, since, as the material cools alpha phase continuously precipitates and the series of reductions at progressively lower temperatures results progressively in structural refinements. In other Words, it is peferred to commence the hot rolling at the more elevated temperatures in the hot rolling temperature range and gradually decrease the temperature in order to refine the grain structure.

The length of time of hot rolling is not critical. The alloy may, if desired, be hot rolled until reaching the lower temperature in the hot rolling temperature range, i.e., 1000 F.

It is an advantage of the alloy of the present invention that the hot rolling characteristics thereof are at least as good as those of much lower strength copper base alloys, such as 70-30 brass, i.e., with respect to, for example, power consumption and amount of reduction per pass.

Subsequent to hot rolling the alloy contains the maximum amount of alpha phase possible, as governed by the phase equilibrium for the particular composition, and in addition a relatively large volume of the previously described dispersion. The maximum amount of alpha phase is obtained by insuring that the alloy, either during or subsequent to hot rolling, is held in the temperature range of 1050 to 1100 F. for at least two minutes. This may be done in a variety of ways either during the hot rolling or by a thermal treatment subsequent thereto. For example, the alloy may be cooled slowly through this temperature range during the normal course of hot rolling and held there for at least two minutes and preferably longer.

Subsequent to the hot working step the alloy is cold worked at a temperature of below 500 F., and preferably from 0 to 200 F.

The term cold working is employed in its conventional sense, although, in accordance with the present invention cold rolling is preferred and the present process will be described in more detail with reference to this preferred mode of operation. Naturally, other methods of cold working will readily suggest themselves to those skilled in the art, for example, drawing, swaging, and cold forging.

As in the above-identified co-pending application Serial No. 328,184, it is especially surprising and unexpected that the alloys of the present invention can be readily cold worked, for example, within the optimum compositional range (9.8 to 10.0 percent aluminum) cold rolling reductions as high as 50 percent are attained, and even higher reductions of over 50 percent aluminum are attained within the broad compositional range (9.0 to 11.8 percent aluminum) toward the low aluminum end.

This surprising and unexpected ability permits the introduction of a whole new class of commercial products utilizing thi composition. Particularly important is that these alloys can now be made commercially available in light gage, coiled strip or sheet form. Such products fill a significant commercial need and have heretofore not been available commercially.

The particular method of cooling the alloy to cold rolling temperature is not critical and any convenient method may be employed at any convenient cooling rate, for example, the alloy may be spray quenched, cooled in water or air cooled.

The reduction effected during the cold rolling step is dependent upon many factors. If no additional rolling steps are to be performed, the alloy may be cold rolled to final gage. The exact percentage reduction in the cold rolling is not critical, with the percentage and number of cold rolling steps dependent upon manufacturing economics. If desired, in order to minimize the cold rolling reduction, the alloy may be reheated within the specified hot rolling range and be further reduced to a smaller thickness for cold rolling.

If desired the alloy may be supplied in this cold rolled form, i.e., temper rolled.

After the desired reduction has been effected in the cold rolling step, the alloy may be annealed at a temperature of from 1000 F. to 1400 F., preferably from 1000 F. to 1100 F. and optimally from 1050 F. to 1100 F. As the annealing temperature is increased, the amount of beta phase increases and if subsequent cooling does not precipitate the maximum amount of alpha phase, the amount of reduction on subsequent cold rolling is reduced.

The particular method of reheating the alloy to this elevated temperature is not especially critical and any convenient heating procedure may be employed. The alloy should be held at this elevated temperature for at least two minutes.

In the preferred embodiment the cold rolling and annealing steps are repeated, preferably a plurality of times. Optimum results have been found at three cycles of cold rolling and annealing. The practice of the present invention, and in particular the three cycles of cold rolling and annealing, effectively develops a fine grained structure. It is this fine grained structure that results in the attainment of a superior combination of strength and ductility in these alloys. If desired the alloy may be supplied in the as-annealed condition also having a fine grain size. This form provides the maximum formability.

The process of the present invention is extremely versatile and a great many variations will readily suggest themselves to those skilled in the art. For example, the alloy may be heat treated after cold rolling at 1100 F. to 1800 F. followed by rapid cooling. The temperature of heat treating varies inversely in relation to the aluminum content, i.e., the lower the aluminum content the higher the temperature of the heat treatment. For the composition containing the optimum amount of aluminum, the heat treatment temperature is 1500 F. to 1650 F. The time at temperature is immaterial, it

being necessary only to allow sufficient time to insure uniformity of temperature. After heat treatment the alloy is rapidly cooled below at least 1000 F.; thereafter, the rate of cooling is not critical. The preferred mode of cooling is to cool in water, however, the alloy may also be oil quenched or cooled in circulating air.

The heat treatment converts most of the alloy to the beta phase. In the rapid cooling, the alloy retains a high proportion of beta phase and the beta phase undergoes a structural transformation known as a martensitic transformation which results in a significant increase in strength and results in an alloy having an excellent combination of strength and ductility. Thus, this combination of heat treatment and rapid cooling will be termed a betatizing procedure.

The dispersion present in the micro-structure of the present alloy acts to effectively inhibit grain growth during betatizing and thereby contributes to a finer final grain size. This is an important distinction between the present alloys and the alloys of co-pending application Serial No. 328,184, since the finer grain size contributes to the improved properties of the present alloys.

In the rapid cooling, it is necessary only that the alloy be cooled rapidly at least to below 1000 F., i.e., to at least below the eutectoid transformation temperature, although the alloy may be rapidly cooled to a lower temperature if desired.

Still greater improvements may be attained by a tempering procedure following betatizing. This results in still better strength, principally yield strength. It is accomplished by holding the alloy for at least 30 minutes at a temperature of from 500 F. to 900 F. and preferably from 600 to 750 F. Still further improvements in strength may be had by cold rolling either prior to or subsequent to tempering.

Upon tempering, the present alloys develop higher strength levels than those of co-pending application Serial No. 328,184 and also gain greater strength during tempering. 'It is believed that this increased gain in strength is due to precipitation hardening effects superimposed upon the normal tempering effects. It is further believed that the precipitation hardening is associated with the precipitation from supersaturated solid solution of the intermetallic compounds referred to above. 1

Another modification of the present invention is to form the annealed alloy into component shapes taking advantage of its excellent formability. The alloy is then heat treated in the formed shape to high stength levels. This is particularly useful in, for example, bellows and diaphragms.

Another modification is to form the annealed or temper rolled alloy into the desired shape. The formed part is then joined by such a treatment as brazing at 1400 F. to 1700 F., during which treatment the part is automatically converted to a high proportion of beta phase and if subsequently rapidly quenched very high strength levels are developed, i.e., betatizing. The presence of the dispersion in the present alloys has the same advantageous effects discussed above.

Alternatively, subsequent to the brazing or heat treatment in the formed shape, further strength increases may be attained due to tempering, with the dispersion having the same beneficial effects discussed above. This may be accomplished by any subsequent treatment either by special thermal treatment or by. additional joining, e.g., soldering, which is carried out in the tempering range.

As will be apparent, the process of the present invention is exceptionally versatile and numerous other modifications will readily suggest themselves to one skilled in the art within the spirit of the present invention.

In accordance with the present invention it has been found that the simple and convenient process discussed above results in a new and improved aluminum-bronze alloy possessing highly desirable, and in fact surprising,

physical properties heretofore unattainable in alloys of this type.

The alloy contains from 9.0 to 11.8 percent aluminum, from 0.05 to 5.0 percent of at least one additional element as defined above, and the balance essentially copper. In addition, the alloy has metallographic structure containing from to 95 percent beta phase and the remainder alpha phase, preferably 85 to 95 percent beta phase. In addition, the alloy contains a dispersion, as discussed above. The alloy has a uniformly fine metallographic grain structure with a particle size less than 0.065 mm., and generally less than 0.040 mm.

The alloys of the present invention possess properties which are unexpected and surprising in alloys of this type, especially with regard to strength and ductility. For example, tensile strengths ranging from 120,000 to 160,- 000 p.s.i. and yield strengths from 60,000 to 80,000 p.s.i. (0.2 percent otfset) may be developed in combination with elongations ranging from 12 to 9 percent. The electrical conductivities are good for alloys of this type, ranging from 10 to 16 percent IACS. In addition, modifications of the present invention improve the properties still further. For example, tempering increases the yield strength considerably, e.g., to from 60,000 to 11,000 p.s.i., at the expense, however, of ductility. In another modification consisting of cold rolling the alloy following an annealing operation, yield strength values as high as 115,000 p.s.i. and higher may be achieved together with tensile strengths as high as 148,000 p.s.i.

Still further, these properties are obtained with retention of the other desirable properties in alloys of this type, for example good brazability, solderability, weldability, corrosion resistance, stress corrosion resistance, and fatigue strength.

The present invention and improvements resulting therefrom will be more readily apparent from a consideration of the following illustrative examples.

Example 1 (A .-C0pper-Aluminum-Iron Alloys Alloys having the following compositions were prepared from a charge of cathode copper, aluminum-iron master alloy and commercial purity aluminum in the form of 1%" x 1%" x 4 /2" chill castings.

. Al9.4%, Fe-5.0%, Cuessentially balance Al9.8%, Fe3.0%, Cuessentially balance Al10.0%, Fe4.0%, Cu-essentially balance Al-l0.0%, P e-1.8%, Cuessentially balance Al10.0%, Fe5.0%, Cuessentially balance \Each of the alloys were hot rolled in the temperature range of from 1600 to 1300 F. Reductions of about 10 to 20 percent per pass were used in reducing the gage from 1.75" to 0.050". These reductions were limited primarily by the roll diameter, with greater reductions readily obtainable especially on alloys containing 10% or more aluminum having all beta structures at 1600 F. and, therefore, exhibiting maximum hot rollability.

Example I(B) Following hot rolling all of the alloys of Example I(A) were betatized at 1150 F. for minutes and subsequently air cooled for maximum cold rollability. In the low temperature, betatized condition the above alloy containing 10.0% Al and 5.0% Fe, for example, could be cold rolled The microstructures of all of the alloys were then further refined by cold rolling from 0.050" to 0.025". This was accomplished in three steps with intermediate annealing at 1150 F. after each cold roll. A grain size of about 0.010 mm. in diameter was developed in the alloys by this cold reduction.

The microstructures of the alloys contained a discrete, uniformly distributed dispersion rich in the additional element iron.

8 Example I (C) Maximum tensile properties were developed in the alloys after the treatment of Example I(B) by betatizing in the range of 1500 to 1750" F. to produce about beta phase and 5% alpha phase. For the 10% Al5.0% Fe alloy, maximum properties were obtained by betatizing at 1550 F. for 30 minutes followed by water quenching to give:

Yield strength p.s.i 56,600 Tensile strength p.s.i 165,100 Elongation percent 10.0

Further improvement in yield strength was accomplished by betatizing at 1570 F. and tempering at 650 F. for one hour to give:

Yield strength p.s.i. 101,500 Tensile strength p.s.i 165,000 Elongation "percent-.. 5.0

Electrical conductivity of the 10% Al5.0% Fe alloy was 10.3% IACS betatized at 1500 F. followed by water quench. Improvement in conductivity was obtained by subsequent tempering at 650 F. for one hour. The electrical conductivity increased to 11.4% IACS.

Similar properties were obtained in the other alloys by achieving a comparable proportion of alpha and beta phase by suitable adjustment of the betatizing temperature.

Example II(A).C0pper-aluminum-ir0n alloys Alloys having the following compositions were prepared from a similar charge as in Example I(A) in the form of 2 /2" x 12" x 30" D.C. castings.

1. Al9.2% Fe-4.4% Cuessentially balance 2. Al9.3 Fe4.3 Cuessentially balance 3. Al9.5 Fe4.9%, Cuessentially balance 4. Ail-10.1%, Crl.06%, Cuessentially balance The alloys were hot rolled in the temperature range of from 1600 to 1300 F. Reductions of about 5 to 10 percent per pass were used in reducing the gage from 2.5" to 0.35", with the reductions being limited by the roll diameter as in Example I(A).

Example II(B) Yield strength p.s.i 50,000 Tensile strength p.s.i 96,000 Elongation "percent" 33 Cold rolling this alloy 54% gave the following properties:

Yield strength p.s.i 115,800 Tensile strength p.s.i 148,000 Elongation percent 2.0

Similar properties were developed in the other alloys.

Example II(C) Maximum tensile properties were developed in the alloys of Example II(B) by betatizing to produce maximum beta phase in a manner after Example I(C) For example, the alloy containing 9.5 A1 and 4.9% Fe was betatized at 1628 F. for 30 minutes followed by water quenching. As a result of this treatment this alloy exhibited:

Yield strength p s 1' 64,000 Tensile strength p s 1' 161,000 Elongation percent 7 Yield strength p.s.i 106,200 Tensile strength p s i 168,000 Elongation percent 5.0

Similar properties were developed in the other alloys of Example lI(B).

Example III(A).-Cpper-alummum-chromium alloys Alloys having the following compositions were prepared from a charge of cathode copper, aluminum-chromium master alloy and commercial purity aluminum in the form of 1% x 1%" x 4 /2" chill castings.

l. Al9.'7%, Crl.2%, Cuessentially balance 2. Al-9.9%, Cr--0.46%, Cu-essentially balance 3. All0.0%, Cr1.04%, Cu-essentially balance 4. Al10.1%, Cr1.06%, Cu-essentially balance Each of the alloys were hot rolled in the temperature range of from 1600 to 1300" F. Reductions of about 10 to 20 percent per pass were used in reducing the gage from 1.75 to 0.050, with reductions being limited by the roll diameter.

Example 111(B) Example 1II(C) Maximum tensile properties were developed in all the alloys in a manner after Example I(C) by betatizing to produce maximum beta phase. For example, the alloy containing 10.1% Al and 1.06% Cr was betatized at 1550 F. for 30 minutes followed by water quenching to give:

Yield strength p.s.i 67,000 Tensile strength p.s.i 162,800 Elongation percent 10 Further improvement in yield strength was accomplished by betatizing at 1570 F. for 30 minutes followed by tempering at 650 F. for one hour to give:

Yield strength p.s.i. 111,700 Tensile strength p s 1' 169,200 Elongation percent 5 Electrical conductivity of this alloy was 12.5% IACS betatized at 1500 F. followed by water quench. Improvement in conductivity was obtained by subsequent tempering at 650 F, for one hour. The electrical conductivity increased to 15.1% LACS.

Similar properties were developed in the other alloys by achieving a comparable proportion of alpha and beta phase by suitable adjustment of the betatizing tempera ture.

Example I V(A).C0pper-alummum-zirconium alloys Alloys having the following compositions were prepared as in Example I(A) in the form of 1%" x 1% x 4 /2" chill castings.

1. Al-9.9% Zr-0.l7%, Cuessentially balance 2. Al10.0%, Zr0.24%, Cuessentially balance 3. Al--10.1%, Zr0.08%, Cuessentially balance Each of the alloys were hot rolled in a manner after Example I(A).

Example IV(B) Following hot rolling all of the alloys of Example IV(A) were betatized in a manner after Example I(B) at 1150 F. for 30 minutes and subsequently air cooled for maximum cold rollability. In the low temperature, betatized condition the above alloy containing 9.9% A1 and 0.17% Zr, for example, could be cold rolled 50 percent.

The microstructures of all of the alloys were then further refined by cold rolling as in Example I(B) to develop a grain size of about 0.010 mm. in diameter. The microstructures of the alloys contained a discrete, uniformly distributed dispersion rich in zirconium.

Example IV(C) Maximum tensile properties were developed in all of the alloys of Example IV(B) by betatizing in a manner after Example I(C) to produce about beta phase and 5% alpha phase. For example, in the above alloy contaning 10.1% Al and 0.08% Zr, maximum properties were obtained by betatizing at 1550 F. for 30 minutes followed by Water quenching to give:

Yield strength p.s.i 82,600 Tensile strength p.s.i 143,000 Elongation percent Further improvement in yield strength was obtained by betatizing at 1570 F. for 30 minutes followed by a water quench and tempering at 650 F. for one hour to give:

Yield strengt p.s.i 115,600 Tensile strength p.s.i 152,200 Elongation percent 2 Electrical conductivity of this alloy was 12.4% IACS betatized at 1500 F. followed by water quench. Improvement in conductivity was obtained by subsequent tempering at 650 F. for one hour to give a value of 13.7% IACS.

Similar properties were developed in the other alloys by achieving a comparable proportion of alpha and beta phase by suitable adjustment of the betatizing temperature.

Example V( A .C 0p per-a l umin um-titaizium alloys Alloys having the following compositions were prepared as in Example I(A) in the form of 1%" x 1%" X 4 /2 chill castings, except that the charcoal cover was removed and a KCl flux cover was used when the aluminum-titanium master alloy was added.

1. Al10.3 Ti2.0% Cu-essentially balance 2. Al-11.4%, Ti1.1%, Cu-essentially balance 3. All 1.6%, Ti--1.2%, Cu-essentially balance Each of the alloys were hot rolled in a manner after Example I(A).

Example V(B) Following hot rolling all of the alloys of Example V(A) microstructures of the alloys contained a discrete, uniformly distributed dispersion rich in titanium.

xample V(C) Maximum tensile properties were developed in all of the alloys of Example V(B) by betatizing in a manner after Example I(C) to produce about 95% beta phase and 5% alpha phase. For example, in the above alloy containing 10.3% Al and 2.0% Ti, maximum properties were obtained by betatizing at 1550 F. for 30 minutes followed by water quenching to give:

Yield strength p.s.i 93,600 Tensile strength p.s.i 143,200 Elongation percent 3 Tempering caused a slight increase in yield strength but a reduction in tensile strength. Electrical conductivity of this alloy was 10.8% IACS betatized at 1500 F. followed by water quench. Improvement in conductivity was obtained by subsequent tempering at 650 F. for one hour to give a value of 13.2% IACS.

Example VI.Cmparative Alloys containing 9.0, 10.0, 10.3, 10.5 and 11.1 percent aluminum and the balance essentially copper were made from a charge of cathode copper and commercial purity aluminum in the form of 1%" x 1%" x 4 /2 chill castings.

The alloys were hot rolled in the temperature range of from 1600 to 1300 F. Reductions of about 10 to 20 percent per pass were used in reducing the gage from 1.75 to 0.1.

Following hot rolling, the alloys were betatized at 1100 F. for 30 minutes and subsequently air cooled for maximum cold rollability.

The microstructures of the alloys were further refined by cold rolling in three steps with intermediate annealing at 1100 F. after each cold roll. The gage was reduced from 0.100" to 0.050". As a result of this cold rolling with inter anneals at 1100 F., grain sizes of about 0.020 mm. in diameter were obtained for each of the above alloys. There was no discrete dispersion, as in the previous examples.

Maximum tensile properties were developed in the alloys by betatizing at suitably high temperatures to produce about 95 percent beta phase and 5 percent alpha phase. For the percent aluminum alloy, maximum properties were obtained by betatizing at 1525 F. for 30 minutes followed by water quenching. As a result of this treatment, the 10 percent aluminum alloy exhibited a yield strength of 53,800 p.s.i., a tensile strength of 125,000 p.s.i. and 8.5 percent elongation. Further improvement in strength was accomplished by tempering at 650 F. for one hour. The yield strength of the 10 percent aluminum alloy was increased to 127,000 p.s.i. with a corresponding reduction in elongation to 1.5 percent.

Example VII.-Comparative An alloy was cast in a manner after Example I containing 9.4 percent aluminum and the balance essentially copper. The alloy was hot worked by extrusion and then drawn into a final plate form. The resultant alloy had a tensile strength of 75,000 p.s.i., a yield strength of 35,000 p.s.i. and an elongation of 28 percent.

The maximum properties that were developed by betatizing at 1600 F. and water quenching were only 109,000 p.s.i. tensile strength, 28,000 p.s.i. yield strength and 29 percent elongation owing to a comparatively coarse grained structure, none of the grains being under 0.065 mm. in diameter.

The response of this material to tempering increased the yield strength only a small amount to about 35,000 p.s.i.

Example VIII.Comparative In a manner after Example I, an alloy containing 12.0 percent aluminum and the balance essentially copper was hot rolled, betatized and cold rolled. Cold rolling was extremely diflicult and at reduction of about 5 percent the alloy fragmented beyond further use.

Example IX.C0mparative An alloy containing 8 percent aluminum and the balance essentially copper was treated in a manner after Example I. The properties attained were: 140,000 p.s.i. tensile strength; and 65,000 p.s.i. yield strength. Further heat treatment did not result in further improvement.

As pointed out heretofore, both the alloys of the present invention and the alloys of co-pending application S.N. 328,184 are extremely versatile and susceptible of a great many uses. For example, in unfired cryogenic pressure vessels wherein exceptionally high weld strengths can be developed. When an alloy in the softened condition, i.e., maximum alpha, is TIG welded using the parent metal as filler, the tensile failures always occur in the base plate. Thus, the properties of the weldrnent are easentially those of the base material.

Other uses of the present alloys and those of the above co-pending application include uses similar to berylliumcopper where high strength and non-sparking is required. Also in cutlery where exceptionally high levels of hardening and cutting ability are obtained by combination of heat treatment and cold rolling. In this application, a high corrosion resistance material will preserve the cutting edge for long periods. In addition, the alloys may be used as Wire alloys in Fourdrinier machines due to their high strength and corrosion resistance, providing superior performance than copper base alloys conventionally used. A further use is as a bearing material in steel backed bearings because of a multi-cornponent structure in which a hard phase can be distributed through a soft matrix.

This invention may be embodied in other form or carried out in other ways without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered as in all respects illustrative and not restrictive; the scope of the invention being indicated by the appended claims, and all changes which come within the meaning and range of equivalency are intended to be embraced therein.

What is claimed is:

1. A high strength cold rolled and heat treated aluminum-bronze alloy having a minimum tensile strength of 120,000 p.s.i., a minimum yield strength of 60,000 p.s.i. at 0.2 percent offset consisting essentially of (A) from 9.0 to 11.8 percent aluminum; (B) from 0.05 to 5.0 percent of at least one additional element having a solid solubility in copper of less than 4.0 percent and which forms at least one intermetallic compound with aluminum, with the total quantity of said additional elements being less than 10.0 percent; and (C) the balance essentially copper, said alloy having a metallographic structure containing from 5 to 95 percent beta phase, wherein the beta phase has a martensitic structure, and remainder alpha phase and having a uniformly fine metallographic grain structure with a grain size less than 0.065 mm., said alloy containing a discrete, uniformly distributed dispersion rich in said additional element.

2. An alloy according to claim 1 containing from to percent beta phase.

3. An alloy according to claim 1 with the total quantity of said additional elements being less than 5 percent.

4. An alloy according to claim 1 wherein said additional element is selected from the group consisting of cent.

6. An alloy according to claim 4 wherein said additional element is chromium in an amount of from 0.4 to

2.0 percent.

7. An alloy according to claim 4 wherein said additional element is titanium in an amount of from 0.4 to

2.0 percent.

8. An alloy according to claim 4 wherein said additional element is zirconium in an amount of from 0.05 to 0.2 percent.

References Cited by the Examiner UNITED STATES PATENTS Richardson 14811.5

Klement 75162 X Klement 75162 Klement 75162 10 HYLAND BIZOT, Primary Examiner.

DAVID L. RECK, Examiner. H. F. SAITO, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 297 ,497 January 10 1967 George H. Eichelman, Jr., et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 43, for "cost of" read cost column 8, line 39, for "Al-10.1%, (Ir-1.06%" read Al-9.6%, e-4.3%

Signed and sealed this 15th day of October 1968.

(SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

Claims

1. A HIGH STRENGTH COLD ROLLED AND HEAT TREATED ALUMINUM-BRONZE ALLOY HAVING A MINIMUM TENSILE STRENGTH OF 120,000 P.S.I., A MINIMUM YIELD STRENGTH OF 60,000 P.S.I. AT 0.2 PERCENT OFFSET CONSISTING ESSENTIALLY OF (A) FROM 9.0 TO 11.8 PERCENT ALUMINUM; (B) FROM 0.05 PERCENT OF AT LEAST ONE ADDITIONAL ELEMENT HAVING A SOLID SOLUBILITY IN COPPER OF LESS THAN 4.0 PERCENT AND WHICH FORMS AT LEAST ONE INTERMETALLIC COMPOUND WITH ALUMINUM, WITH THE TOTAL QUANTITY OF SAID ADDITIONAL ELEMENTS BEING LESS THAN 10.0 PERCENT; AND (C) THE BALANCE ESSENTIALLY COPPER, SAID ALLOY HAVING A METALLOGRAPHIC STRUCTURE CONTAINING FROM 5 TO 95 PERCENT BETA PHASE, WHEREIN THE BETA PHASE HAS A MARTENSITIC STRUCTURE, AND REMAINDER ALPHA PHASE AND HAVING A UNIFORMLY FINE METALLOGRAPHIC GRAIN STRUCTURE WITH GRAIN SIZE LESS THAN 0.065 MM., SAID ALLOY CONTAINING A DISCRETE, UNIFORMLY DISTRIBUTED DISPERSION RICH IN SAID ADDITIONAL ELEMENT.