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→5.1.6.1 Copper-Beryllium Alloys (Beryllium Bronze)
The cause for precipitation hardening of CuBe materials is the rapidly diminishing solubility of beryllium in copper as temperature decrease. As the
phase diagram for CuBe shows, 2.4 wt% of Be are soluble in Cu at 780°C ''<xr id="fig:Phase diagram of copperberyllium with temperature ranges for brazing and annealing treatments"/> (Fig. 5.28)''. In this temperature range annealed CuBe alloys are homogeneous(solution annealing). The homogeneous state can be frozen through rapid cooling to room temperature (quenching). Through a subsequent annealing at 325°C the desired precipitation hardening is achieved which results in a significant increase in mechanical strength and electrical conductivity of CuBe ''(Table 5.17)''. The final strength and hardness values depend on the annealing temperature and time as well as on the initial degree of cold working ''(Table 5.18)'' and ''(Figs. 5.29 - 5.31)''.
<figure id="fig:Phase diagram of copperberyllium with temperature ranges for brazing and annealing treatments">
Fig. 5.28: Phase diagram of copperberyllium with temperature ranges for brazing and annealing treatments
[[File:Phase diagram of copper beryllium with temperature ranges.jpg|right|thumb|Phase diagram of copper- beryllium with temperature ranges for brazing and annealing treatments]]
</figure>
As precipitation hardening alloys CuBe materials, mainly CuBe2 and CuBe1.7 have gained broad usage as current carrying contact springs because of their outstanding mechanical properties. Besides these CuCo2Be and CuNi2Be, which have medium mechanical strength and a relatively high electrical
