The effect of transmutation and displacement in irradiated copper for heat-sink materials

Abstract

High-energy neutron irradiation on copper alloys will cause atomic displacements and nuclear transmutation, which will lead to degradation of thermal conductivity and mechanical properties. To study the synergistic effects, we have utilized Cu–Ni–Zn alloys to simulate the effect of transmutation. Thermal conductivity of these alloys has been derived from electrical resistivity measurements between 298 and 770 K. These alloys were also irradiated with 2.4 MeV copper self ions at room temperature and the mechanical properties were evaluated from micro-hardness measurements. The resistivity of the copper alloys depends linearly on nickel concentration. However, the effect of zinc is complex and may be less prominent than the nickel effect. It is suspected that dezincification has taken place. The change in micro-hardness shows saturation at a displacement dose of around 0.5 dpa. There is a slight influence of alloying elements, particularly zinc, on the fluence dependence of hardness change.