Changes

====<!--5.1.4.1-->Copper-Zinc Alloys Test (Brasses)====

Because of their good elastic spring properties and formability the copper-tin alloys CuSn6 and CuSn8 are standard materials for spring contact elements in electrome-chanical components such as connectors, switches, and relays <xr id="tab:Physical Properties of Copper-Tin Alloys"/><!--(Tab. 5.9)--> and <xr id="tab:Mechanical Properties of Copper-Tin Alloys"/><!--(Tab.5.10)-->. Besides these other alloys such as CuSn4 and CuSn5 and the multi-metal tin bronze CuSn3Zn9 have significant usage – mainly in North America. <!--Figure 5.10--> <xr id="fig:Phase diagram of the Cu-Sn system for the range of 0 – 30 wt% Sn"/> shows the copper rich side of the phase diagram for the CuSn system. The mechanical property values achieved by cold forming are superior to these of the brass alloys <xr id="fig:Mechanical properties of tin bronze depending on the tin content (cold working 0 and 50%)"/><!--(Fig. 5.11)-->. They increase significantly with increasing Sn content. The work hardening and softening behavior are shown for the example of CuSn8 in <xr id="fig:Strain hardening of CuSn8 by cold working"/><!--Figures 5.12--> and <xr id="fig:Softening of CuSn8 after 3 hrs annealing after 50% cold working"/><!--Fig. 5.13-->. The stress relaxation properties for CuSn alloys are good for up to 100°C, deteriorate however quickly for temperatures above 150°C.

====<!--5.1.4.3 -->Copper-Nickel-Zinc Alloys (German Silver)====

Despite its lower electrical conductivity, the good spring properties, high corrosion resistance, and the good workability make copper-nickel-zinc alloys a frequently used spring contact carrier in switches and relays. As illustrated in the phase diagram the most commonly used materials are in the &alpha; -range which means that they are single-phase alloys <xr id="fig:Copper rich region of the ternary copper-nickel-zinc phase diagram with indication of the more commonly available german silver materials"/> <!--(Fig. 5.14)-->. The formability and strength properties of german silver are comparable to those of the copper-tin alloys. The work hardening and softening behavior is illustrated on the example of CuNi12Zn24 in <xr id="fig:Strain hardening of CuNi12Zn24 by cold working"/> <!--Figures 5.15 --> and <xr id="fig:Softening of CuNi12Zn24 after 3 hrs annealing after 50% cold working"/> <!--5.16-->.

<caption>'''<!--Table 5.11: -->Physical Properties of Copper-Nickel-Zinc Alloys'''</caption>

<caption>'''<!--Table 5.12: -->Mechanical Properties of Copper-Nickel-Zinc Alloys'''</caption>

<xr id="fig:Copper rich region of the ternary copper-nickel-zinc phase diagram with indication of the more commonly available german silver materials"/> <!--Fig. 5.14: --> Copper rich region of the ternary copper-nickel-zinc phase diagram with indication of the more commonly available german silver materials

<xr id="fig:Strain hardening of CuNi12Zn24 by cold working"/> <!--Fig. 5.15: --> Strain hardening of CuNi12Zn24 by cold working

<xr id="fig:Softening of CuNi12Zn24 after 3 hrs annealing after 50% cold working"/> <!--Fig. 5.16: --> Softening of CuNi12Zn24 after 3 hrs annealing after 50% cold working

====<!--5.1.4.4 -->Copper-Silver-(Cadmium) Alloys (Silver Bronze)====

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 <xr id="fig:Phase diagram of copper-silver for the range of 0 – 40 wt% silver"/> <!--(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 <xr id="tab:tab5.13"/> <!--(Tab. 5.13) --> and <xr id="tab:tab5.14"/> <!--(Tab. 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 [[#figures5|(Figs. 13 – 15)]]<!--(Figs. 5.18 – 5.20)-->. For the relaxation behavior the silver bronzes are superior to German silver and tin bronze.

<caption>'''<!--Table 5.13: -->Physical Properties of Selected Copper-Silver-(Cadmium) Alloys'''</caption>

<caption>'''<!--Table 5.14: -->Mechanical Properties of Selected Copper-Silver-(Cadmium) Alloys'''</caption>

<xr id="fig:Phase diagram of copper-silver for the range of 0 – 40 wt% silver"/> <!--Fig. 5.17: --> Phase diagram of copper-silver for the range of 0 – 40 wt% silver

<xr id="fig:Strain hardening of CuAg2 by cold working"/> <!--Fig. 5.18: --> Strain hardening of CuAg2 by cold working

<xr id="fig:Softening of CuAg2 after 1 hr annealing after 40% cold working"/> <!--Fig. 5.19: --> Softening of CuAg2 after 1 hr annealing after 40% cold working

<xr id="fig:Softening of CuAg2 after 1 hr annealing after 80% cold working"/> <!--Fig. 5.20: --> Softening of CuAg2 after 1 hr annealing after 80% cold working