US2030921A - Copper-beryllium alloys - Google Patents

Description

Patented Feb. 18, 1936 COPPER-BEBYIJJUM ALLOYS Werner Hessenbruch, Hanau-on-the- Germany, assignor to Heeus-Vacuumschmelse,

ermany No Drawing. Application June 15, 1934, Serial N0. 730,727. In Germany June 17, 1933 2 Claims. (Cl- 75-1) This invention relates to improvements in copper beryllium alloys. Its nature, objects and advantages wlll be best understood from the 101- lowing.

5 If one adds to copper about 3.0% beryllium, one gets alloys improvable by heat treatment, which, after quenching at about 750 C. and subsequent heating to about 250 C. to 350 C., show a sharp increase of hardness and of other mechanical properties. I These alloys have, how-'- ever, the disadvantage that on account of the high beryllium content their price is so high that frequently they cannot be produced economically. Furthermore, the binary alloys of' copper and berylliumshow phenomena of softening if the temperature necessary for heat treatment is maintained for a substantial period, the softening occurring because the beryllid segregates and agglomerates in certain places. Cold working, in

:0 addition, introduces the detrimental influence of re-crystallization. The net result is that heat treated pieces or parts assume, after a short time, a comparatively considerable hardness but lose this hardness on remaining a certain time at a temperature of from about 300 C. to 400 C.

I have discovered that this softening may be overcome and that also the amount of beryllium for a determined hardness may be reduced. I obtain these results by adding titanium, which will 80 alloy with the copper but decreases the solubility of the beryllium in the solid copper, i. e., by decreasing the amount of alpha mixed crystals. Experiments have shown that nearly all additions of other elements to copper beryllium decrease the'territory of the alpha-mixed crystals with the exception of nickel.

Aside from thus influencing the territory of the mixed crystals, the addition of titanium increases the crystallization temperature so that with such 40 alloys the danger of the softening is considerably less than with the binary copper-beryllium alloys.

Extensive investigations with many various additions have shown that the best results with respect to improvement by heat-treatment can be obtained by employing titanium which, by itself,

is able to form copper alloys improvable by heat treatment. Nickel, the alkaline metals, the low melting metalloids and the noble gases, apparently are not suitable. 5.

The surprising efiect of additions of the character above described is shown by the following examples. If one adds about 1% of beryllium to copper, heat treatment of 350 C. has practically no effect. The critical hardness oi Brinell 10 rises only to Brinell in 14 hours. If one adds to the copper, in addition to the 1% of beryllium, for instance 3% titanium, .the hardness after heat treatment of about 10 hours rises to 260 Brinell. If one starts with a hard worked piece 15 of this alloy which before had already to 200 Brinell, the hardness by heattreatment up to 1350 C. rises to about 280 to 300 Brinell and remains constant even for a long time. By more cold working it is even possible to still increase 2 the intial hardness without disturbing the efiect of the heat treatment on account of recrystallization.

I prefer to employ beryllium in substantial amounts above a trace up to 2.5%, although I 25 may go as high as 3%. i

I prefer to use titanium in a range of from about 0.5% to about 8%. This metal will alloy with copper but tends to reduce the solubility of beryllium in the copper on heat treatment, which 30 gives the best results.

The copper in all cases should be the base metal of the alloy and should constitute above 50% of the total;

1. An alloy consisting of beryllium in quantities in excess of a trace up to about 3%, titanium from about .5% to about 8%, and the balance copper.

2. An alloy consisting of beryllium in quantities 40 in excess of a trace up tc about 3%, titanium in an amount about 3%, and the balance copper.

WERNER HESSENBRUCH.