The influence of neutron irradiation on the fatigue performance of OFHC copper and a dispersion strengthened copper alloy

The fatigue performance of pure copper of the oxygen free, high conductivity (OFHC) grade and a dispersion strengthened copper alloy, Glid CopTM CuAl-25 was examined with and without irradiation exposure. Mechanical testing was carried out to establish the fatigue lives of these materials in the unirradiated and irradiated states. Fatigue specimens of these two materials were irradiated with fission neutrons in the DR-3 reactor at Risoe with a flux of ∼2.5 x 10-17 n/m2 s (E 1 MeV) to fluence levels of 1.5-2.5 x 1024 n/m2 (E 1 MeV) at ∼47 and 100 C. Specimens irradiated at 47 C were fatigue tested at room temperature, whereas those irradiated at 100 C were tested at the irradiation temperature. These investigations demonstrated that, while irradiation causes significant hardening of the materials, the hardening appears to have no negative impact on fatigue performance. In fact, the fatigue performance of the CuAl-25 alloy is considerably better in the irradiated than that in the unirradiated state tested both at 22 C and 100 C. Microstructural observations of the fatigue microstructures and the fracture surfaces are useful in understanding this conclusion. (orig.)