Fracture behavior of high-strength, high-conductivity copper alloys

The fracture behavior of three copper alloys, namely, one dispersion-strengthened alloy: GlidCopTMCuAl25, and two precipitation-hardened alloys: Hycon3HPTMCuNiBe and Elbrodur CuCrZr, was investigated in the temperature range 20-300 deg. C in vacuum. The results show that all these three alloys experienced a loss of fracture resistance with increasing test temperature. In the case of the CuNiBe alloy, the fracture resistance drops very rapidly as test temperature increases, and the other two alloys also experience drops in toughness, but not quite to the same extent. In fact, the fracture resistance of CuCrZr is affected only moderately by test temperature. The reduction of fracture resistance with increasing temperature in vacuum shows that the environment is not the only factor responsible for poor toughness. Further, microstructural analysis of the CuNiBe alloy shows that changes in grain boundary microstructure resulted from discontinuous precipitation. This is assumed to have a significant effect on the fracture behavior of this alloy