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→5.1.4.2 Copper-Tin Alloys (Tin Bronze)
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 ''(Tables 5.9 and 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 softeningbehavior 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"/> 5.13. The stress relaxation properties for CuSn alloys are good for up to 100°C, deteriorate however quickly for temperatures above 150°C.
Fig. 5.9: Softening of CuZn36 after 3 hrs annealing after 50% cold working
[[File:Softening of CuZn36 50.jpg|right|thumb|Softening of CuZn36 after 3 hrs annealing after 50% cold working]]
<figure id="fig:Phase diagram of the Cu-Sn system for the range of 0 – 30 wt% Sn">Fig. 5.10: Phase diagram of the Cu-Sn system for the range of 0 – 30 wt% Sn.
[[File:Phase diagram of the Cu Sn system.jpg|right|thumb|Phase diagram of the Cu-Sn system for the range of 0 – 30 wt% Sn]]
</figure>
'''Table 5.7: Physical Properties of Selected Copper-Zinc Alloys'''
2 teile!
<figure id="fig:Mechanical properties of tin bronze depending on the tin content (cold working 0 and 50%)">
Fig. 5.11: Mechanical properties of tin bronze depending on the tin content (cold working 0 and 50%)
[[File:Mechanical properties of tin bronze depending on the tin content.jpg|right|thumb|Mechanical properties of tin bronze depending on the tin content (cold working 0 and 50%)]]
</figure>
<figure id="fig:Strain hardening of CuSn8 by cold working">
Fig. 5.12: Strain hardening of CuSn8 by cold working
[[File:Strain hardening of CuSn8 by cold working.jpg|right|thumb|Strain hardening of CuSn8 by cold working]]
</figure>
<figure id="fig:Softening of CuSn8 after 3 hrs annealing after 50% cold working">
Fig. 5.13: Softening of CuSn8 after 3 hrs annealing after 50% cold working
[[File:Softening of CuSn8 50.jpg|right|thumb|Softening of CuSn8 after 3 hrs annealing after 50% cold working]]
</figure>
====5.1.4.3 Copper-Nickel-Zinc Alloys (German Silver)====