Tension tests and fractography were used to examine the radiation-induced evolution of Cu-5Ni and three commercially prepared precipitation-strengthened alloys after irradiation in the Fast Flux Test Facility (FFTF) at 684 and 800 K. The addition of nickel to copper resulted in increased ductility prior to irradiation but decreased ductility after irradiation. The postirradiation difference appears to arise from the influence of nickel on void swelling.

The precipitation-strengthened alloys in general exhibited drops in yield strength after irradiation and increased ductility. The major effect appeared to be related primarily to overaging of the precipitates (radiation-enhanced recrystallization).