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 conductivit y (OFHC) grade and a dispersion strengthened copper alloy, Glid Cop(TM) CuA l-25 was examined with and without irradiation exposure. Mechanical testing was carried out to establish the fatigue lives of these materials in the u nirradiated and irradiated states. Fatigue specimens of these two materials were irradiated with fission neutrons in the DR-3 reactor at Ris phi with a flux of approximate to 2.5 x 10(-17) n/m(2) s (E > 1 MeV) to fluence leve ls of 1.5-2.5 x 10(24) n/m(2) (E > 1 MeV) at approximate to 47 and 100 degr ees C. Specimens irradiated at 47 degrees C were fatigue tested at room tem perature, whereas those irradiated at 100 degrees C were tested at the irra diation temperature. These investigations demonstrated that, while irradiat ion causes significant hardening of the materials, the hardening appears to have no negative impact on fatigue performance. In fact, the fatigue perfo rmance of the CuAl-25 alloy is considerably better in the irradiated than t hat in the unirradiated state tested both at 22 degrees C and 100 degrees C . Microstructural observations of the fatigue microstructures and the fract ure surfaces are useful in understanding this conclusion. (C) 1999 Elsevier Science B.V. All rights reserved.