US2135254A - Copper alloys - Google Patents

Description

Patented Nov. 1, 1 938 UNITED STATES PATENTIOFFICE, 42,135,254 I.

COPPER ALLOYS No Drawing. Original application'September 15,

1937, Serial No. 164,038.

Divided and this application July 19, 1938, Serial No. 220,007

2 Claims.

This invention relates to alloys and more particularly to copper alloys of improved characteristics.- 1

The present application is a division of our co-pending application, Serial Number 164,038, filed September 15, 1937.

An object of the invention is to produce an improved copper base alloy.

Another object is to produce a copper-cadmium-cobalt alloy, having a high wear resistance.

Other objects-of the invention will be apparent from the following description taken in connection with the appended claims.

The present invention comprises a combination of elements, methods of manufacture and the product thereof, brought out and exemplified in the disclosure hereinafter set forth, the scope of the invention being indicated in the appended claims.

-While a preferred embodiment of the invention is described herein, it is contemplated that considerable variation may be made in the method of procedure and .the combination of elements without departing from the spirit of the invention.

According to the present invention, coppercobalt-cadmium are improved by the addition of beryllium, which tends to produce an intermetallic compound with the base-forming element present in the alloy; namely, cobalt. By means of the formation of an intermetallic compound, the ternary copper-cobalt-cadmium alloys can be made of greater hardness, which hardness is. also being retained at high temperatures.

According to the preferred method of carrying out the present invention,an alloy is made containing copper, cadmium and cobalt, plus beryllium, in the following proportions:

Percent Cadmium 0.1 to 10 Cobalt 0.1 to 10 Beryllium 0.01 to 5 Copper Balance.

It is possible likewise to improve the characteristics of other copper-cadmium-cobalt alloys con taining small percentages of additional ingredients, by the addition of the above-mentioned compound-forming element. Thus, copper-cadmium-cobalt alloys, containing small proportions of silver, zinc, tin, calcium, lithium, iron, nickel and manganese, can be improved by the addition of compound-forming element beryllium in substantially the proportions indicated above.

The alloy can be made according to standard alloying methods. Thus, analloy of copper and .tween 400 to 600 degrees C. Thisheat treatment alloy hasbeen prepared according to these standard methods, the heat treatment may be carried out as follows:

Thealloy is raised in temperature to above 700 degrees C. and preferably to a temperature in the'order of 800 to 1,000 degrees C. The alloy is then quenched from this high temperature and subsequently aged at a temperature below 700 degrees-C. and preferably in the range beresults in a considerable improvement of hardness in the alloy and hardness'values can be reached exceeding Rockwell, B. Another remarkable effect of the heat treatment is a marked 25 improvement in the electrical conductivity. .With some alloy combinations within the percentage range given above, a conductivity of 65% of that of pure copper has been obtained.

1 This alloy is therefore well suited for use at comparatively high temperatures, since the hardness and electrical conductivity are maintained for indefinite periods at the aging temperatures indicated above. Heat treated alloys,'with or without cold working, will retain their-properties at a temperature of 450 degrees 0., almost indefinitely. I

' Alloys which are intended for casting purposes have a preferred cadmium content of from 0.5 to 5%, while in alloys which are intended for further cold or hot working, the maximum cadmium content should be 1.5%. The material in the cast condition has a fairly high'hardness of 40 to 60 Rockwell B. This hardness can be increased by the aging treatment described above. 45 Instead of giving both treatments to the casting,

it is also possible to eliminate the quenching treatment, because the material usually gets partly chilled during the casting process and all that is necessary is. to apply the second heat treat- 50 .ment, which is generally known as the aging treatment. The materials made in accordance with the present invention were tested for con-- tact resistance after being operated as contactor contacts. It was found that the contact resistelectric machines.

suitable for welding electrode tips and welding ance remained very low during long periods of operation, the combined presence of cadmium and cobalt being responsible for the oxide oi low resistivity, while the compound forming element produced a mechanical hardness which gave the material a wear resistance superior to that of the ternary alloy of copper, cobalt, and cadmium.

The tensile properties of alloys containing cadmium, ranging from 0.25 to 1%; cobalt, from 0.5 to 5%; and beryllium, ranging from 0.3 to 1%, will reach values of 90,000 to 110,000 p. s. i., with an elongation of 10% or better, measured in 2 inches. The alloys also have very fine grain structure, which improves the physical properties.

The alloys prepared, as indicated above, are well suited for the manufacture of castings, such as commutator segments or collector rings'for In addition, these alloys are 0 wheels.

alloys is in the manufacture of a material, which must be resistant to atmospheric corrosion and to electrical erosion. The materials can also be used for parts where high thermal conductivity with high strength, are needed.

While the present invention as to its objects and advantages has been described herein, as

' the balance copper.

2. An alloy containing 0.25 to 1% cadmium, 0.5 to 5%- cobalt, 0.3 to 1% beryllium and the balance copper, said alloy having high tensile strength and fine grain structure.

' FRANZ R. HENSEL.

EARL I. LARSEN.