Naturally Hard Copper Alloys

Alloys like brasses (CuZn), tin bronzes (CuSN), and German silver (CuNiZn), for which the required hardness is achieved by cold working are defined as naturally hard alloys. Included in this group are also the silver bronzes (CuAg) with 2 – 6 wt% of Ag.

5.1.4.1 Copper-Zinc Alloys (Brasses)

Copper-zinc alloys are widely used as contact carrier materials in switching devices for electrical power engineering because of their high electrical conductivity, the higher mechanical strength combined with good formability compared to pure copper (Tables 5.7 and 5.8), and at the same time their reasonable economic costs. Especially suitable are the brasses with up to 37 wt% Zn content which are according to the phase diagram all made up from the " -phase of the CuZn system (Fig. 5.5). it is important to note the strong dependence of the electrical conductivity and mechanical strength on the zinc content (Fig. 5.6).