US2126386A - Copper-silver-beryllium-magnesium alloy - Google Patents

Description

' Patented Aug. 9, 1938 UNITED STATES PATENT. OFFICE COPPER- SILVER-BERYLLIUM-MAGNE- SIUM ALLOY Franz R. Hensel and Earl I.- Larsen, Indianapolis,

Ind., assignors to P.

It. Mallory & 60., Inc.,

Indianapolis, Ind., a corporation of Delaware No Drawing. Original application October 12,

1937, Serial No. 168,568. Dividedand this application May 27, 1938, Serial No. 210,443

4 Claims. (01. 75-153 Another object is to improve a copper-silver 10 alloy which can be age hardened by the additions of beryllium;

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

The present invention-comprises the 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 20 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 as Without departing from the spirit of the invention.

We are aware that a. great deal of work has been done on silver-copper-beryllium alloys. In most cases, however, the silver content wasrather so high and we are not aware of anyl prior art on silver contents below 5%. Silver is a rather expensive element and the alloys produced up to the present time have not found commercial use, because of their high price. In our re:

5 searches, we have discovered that considerably lower percentages of silver can beemployed than heretofore described, and that very excellent properties are obtained with such alloys.

Copper-silver alloys are susceptible to age 40 hardening. This age hardening, however, is manifested. more in improvements in electrical conductivity than in improvements in hardness. ,The hardness of alloys usually has to'be obto the very, limited solid solubility of silver in copper.

We have found that at 600' degrees ones proximately 2.5% silver is heldin solid solution,

55 while at 200 degrees 0., only 3% of silver is held in solid solution, and at room temperature, this solubility is still less. Thisindicates definitely that with small percents of silver, below 5% definite effects can be obtained, as for as precipitation hardening is concerned.

By combining the effects of age hardening of the copper-silver and the copper-beryllium system, an alloy can be produced which shows a very high hardness obtained with the copperberyllium system and an improved electrical conductivity, such as is obtained in the coppersilver system.

According to the present invention the alloy is further improved by the addition of magnesium.

The alloy may preferably contain the essential ingredients in the following proportions:

Percent Beryllium 0.03 to 3 Silver 0.05'to 4- Magnesium 0.05 to Copper Balance Within these composition ranges, there are a number of specific alloys which have been found to be of particular importance. Twb of the alloys are listed below:

\ Percent A. Magnesium 0.1 to2 Beryllium 0.2 to 1 Silver 0.1 to 2.5 Copper Balance Percent 3. Magnesium 0.1 to 2 Beryllium 1 to 2.3 Silver I 0.1 to 2.5 Coppernnr Balance The alloys can be made according to standard alloying methods, such as melting the copper and adding the desired amounts oi silver and magnesium. Afterwards the correct amount of beryllium may be introduced in the form of a copper-beryllium master alloy or any other form and the material can be cast either in a chill mould or in sand mould, at the correct temperature.

Aiter the alloy has been prepared according to standard alloying methods, the heat treatment may be carried out as follows: i

I The alloy in the form of a billet or a sand casting or. any desired form, is raised in temperature a to above 700 degrees C. and its melting point. The alloy is then quenched from this temperature and subsequently aged. at temperatures at or below 600 degrees C. This heat treatment results in considerable improvements in the physical properties of the alloy. The alloy is particularly suitable for applications where high hardness and high electrical conductivity are required and where physical properties have to be retained at elevated temperatures. The alloys have found further very extensive use in applications where the material is used for electrical contacting purposes, such as contactor contacts where arcs are drawn and surface oxidation produces high,

resistance films on ordinary copper alloys.

The alloys have further found considerable use for wear resistance purposes and applications, such as pressure welding electrodes and resistance welding dies in general.

The alloys are furthermore very suitable for springs, particularly springs which have to carry current or which have to withstand certain temperature rises without losing their elastic properties.

The material is also suitable for special applications where springs of intricate design must be formed in the soft condition; that is, after quenching, and where a high hardness can be reached after a suitable age hardening treatment.

The alloys can be manufactured into the form of extruded bars, or sheets or fine wire. The alloys have also particular merit if used in the form of sand castings. Certain compositions, particularly with higher cadmium contents, can not be hot or cold worked, but are ideally suitable for making strong and hard copper base castings.

The alloys are particularly suitable for any parts in electrical machinery where the silver content, in combination with the beryllium content, produces the desirable characteristics required for such applications.

. While the present invention as to its objects and advantages has been described herein, as carried out in specific embodiments thereof, it is not desired to be limited thereby but it is intended to cover the invention broadly within the spirit and scope of the appended claims.

What is claimed is: 1. An alloy composed of 0.03 to 3% beryllium, 0.05 to 4% silver, 0.05 to 10% of magnesium and the balance copper.

2. An age-hardened alloy composed of 0.03 to 3% beryllium, 0.05 to 4% silver, 0.05 to 10% of magnesium and the balance substantially all copper, characterized by high hardness and electrical conductivity and further characterized by