Effect of bonding and bakeout thermal cycles on the properties of copper alloys irradiated at 350°C

Screening experiments were carried out to determine the effect of bonding and bakeout thermal cycles on microstructure, mechanical properties and electrical resistivity of the oxide dispersion strengthened (GlidCop, CuAl-25) and the precipitation hardened (CuCrZr, CuNiBe) copper alloys. Tensile specimens were given heat treatments corresponding to solution anneal, prime-aging, bonding thermal treatment followed by re-aging and the reactor bakeout treatment. A number of specimens were irradiated at 350°C to a dose level of ≃0.3 dpa in the DR-3 reactor at Risø. Both unirradiated and irradiated specimens were tensile tested at 350°C. The microstructure and electrical resistivity were determined in the unirradiated and irradiated conditions. The post-deformation microstructure and fracture surfaces of unirradiated and irradiated specimens were examined. The main results are described and their salient features discussed. The most significant effect of neutron irradiation is a severe loss of ductility in the case of CuNiBe alloys.