Changes

====<!--5.1.6.2 -->Other Precipitation Hardening Copper Alloys====

=====<!--5.1.6.2.1 -->Copper-Chromium Alloys=====

As the phase diagram shows, copper-chromium has a similar hardening profile compared to CuBe <xr id="fig:Copper corner of the copper-chromium phase diagram for up to 0.8 wt% chromium"/><!--(Fig. 5.32)-->. In the hardened stage CuCr has limitations to work hardening. Compared to copper it has a better temperature stability with good electrical conductivity. Hardness and electrical conductivity as a function of cold working and precipitation hardening conditions are illustrated in [[#figures8|(Figs. 6 – 9)]] <!--Figs. 5.33-5.35-->, <xr id="tab:Physical Properties of Other Precipitation Hardening Copper Alloys"/> <!--(Tables 5.19) --> and <xr id="tab:Mechanical Properties of Other Precipitation Hardening Copper Alloys"/> <!--(Tab. 5.20)-->.

<xr id="fig:Copper corner of the copper-chromium phase diagram for up to 0.8 wt% chromium"/> <!--Fig. 5.32: --> Copper corner of the copper-chromium phase diagram for up to 0.8 wt% chromium

<xr id="fig:Softening of precipitation hardened and subsequently cold worked CuCr1"/> <!--Fig. 5.33: --> Softening of precipitation-hardened and subsequently cold worked CuCr1 after 4hrs annealing

<xr id="fig:Electrical conductivity of precipitation hardened CuCr 0.6"/> <!--Fig. 5.34 a: --> Electrical conductivity of precipitation hardened CuCr 0.6 as a function of annealing conditions

<xr id="fig:Hardness of precipitation hardened CuCr 0.6"/> <!--Fig. 5.34 b: --> Hardness of precipitation hardened CuCr 0.6 as a function of annealing conditions

<xr id="fig:Electrical conductivity and hardness of precipitation hardened CuCr 0.6"/> <!--Fig. 5.35: --> Electrical conductivity and hardness of precipitation hardened CuCr 0.6 after cold working

<caption>'''<!--Table 5.19: -->Physical Properties of Other Precipitation Hardening Copper Alloys'''</caption>

<caption>'''<!--Table 5.20: -->Mechanical Properties of Other Precipitation Hardening Copper Alloys'''</caption>

=====<!--5.1.6.2.2 -->Copper-Zirconium Alloys=====

The solubility of Zirconium in copper is 0.15 wt% Zr at the eutectic temperature of 980°C <xr id="fig:Copper corner of the copper zirconium for up to 0.5-wt zirconium"/> <!--(Fig. 5.36)-->. Copper-zirconium materials have a similar properties spectrum compared to the one for copper-chromium materials. At room temperature the mechanical properties of copper-zirconium are less suitable than those of copper chromium, its temperature stability is however at least the same.

=====<!--5.1.6.2.3 -->Copper-Chromium-Zirconium Alloys=====

The earlier used CuCr and CuZr materials have been partially replaced over the years by the capitation hardening three materials alloy CuCr1Zr. This material exhibits high mechanical strength at elevated temperatures and good oxidation resistance as well as high softening temperatures. In its hardened condition CuCr1Zr has also a high electrical conductivity <xr id="fig:Softening of CuCr1Zr after 1hr annealing"/> <!--(Bild 5.37)-->. Their usage extends from mechanically and thermally highly stressed parts such as contact tulips in high voltage switchgear to electrodes for resistance welding.

<xr id="fig:Copper corner of the copper zirconium for up to 0.5-wt zirconium"/> <!--Fig. 5.36: --> Copper corner of the copper- zirconium for up to 0.5 wt% zirconium

<xr id="fig:Softening of CuCr1Zr after 1hr annealing"/> <!--Fig. 5.37: --> Softening of CuCr1Zr after 1 hr annealing and after 90% cold working