Effect of irradiation on the deformation of copper and copper-aluminium alloys

Abstract

The effect of low-temperature irradiation (<70°C) on the deformation of pure copper, Cu-0.09 wt% Al alloy, and Cu-0.19 wt% Al alloy was investigated. Tensile specimens were prepared from single crystals of various orientations, and were exposed to a neutron fluence of 6.85 ×1019 n/cm2(E>1 MeV) at a temperature less than 70°C. All irradiated and unirradiated specimens were pulled. A large increase in critical shear stress due to irradiation was observed; the increase was smaller in Cu-0.19 wt% Al alloy than in pure copper and Cu-0.09 wt% Al alloy. Ultimate shear stress and shear strain were less influenced by irradiation. Yield points were observed in all irradiated specimens. The yield drop was large in irradiated pure copper, and decreased with the increase of aluminium content in copper-aluminium alloys. All unirradiated specimens showed a high work-hardening coefficient (n) in the beginning of the deformation, followed by a lower value. By irradiation, the first value drastically decreased, while the second remained nearly constant. Shear stress and shear strain were influenced by crystal orientation.