Changes

Besides the low-allowed CuAg0.1 other copper materials with higher silver contents (2-6 wt%) are also used as contacts carrier materials. Some of them contain additionally 1.5 wt% Cd. The phase diagram ''(Fig. 5.17) '' shows that in principle the CuAg alloys can be precipitation hardened, but the possible increase in mechanical strength is rather small. Copper-silver alloys have good spring properties and compared to other spring materials have a high electrical conductivity ''(Tables 5.13 and 5.14)''. The mechanical strength values in the strongly worked condition are comparable to those of the copper-tin alloys. Work hardening and softening behavior are shown for the example of CuAg2 ''(Figs. 5.18 – 5.20)''. For the relaxation behavior the silver bronzes are superior to German silver and tin bronze. Because of their good spring properties combined with high electrical conductivity silver bronzes are suitable for the use contact springs in relaysunder higher current loads. Taking advantage of their high temperature stability they are also used as current carrying contacts in high voltage switchgear and as electrode material for resistance welding. Fig. 5.17: Phase diagram of copper-silver for the range of 0 – 40 wt% silver Table 5.13: Physical Properties of Selected Copper-Silver-(Cadmium) Alloys (2 teile!) Table 5.14: Mechanical Properties of Selected Copper-Silver-(Cadmium) Alloys (2 teile!) Fig. 5.18: Strain hardening of CuAg2 by cold working Fig. 5.19: Softening of CuAg2 after 1 hr annealing after 40% cold working Fig. 5.20: Softening of CuAg2 after 1 hr annealing after 80% cold working