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

The fracture behavior of three copper alloys, namely, one dispersion-streng thened alloy: GlidCop(TM)CuAl25, and two precipitation-hardened alloys: Hyc on3HP(TM)CuNiBe and Elbrodur CuCrZr, was investigated in the temperature ra nge 20-300 degreesC 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 rapid ly 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 show s that the environment is not the only factor responsible for poor toughnes s. 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. (C) 2000 Elsevier Science B.V. All rights reserved.