Effect of neutron irradiation on the deformation of copper and internally oxidized copper-aluminium alloy

The effect of neutron irradiation on the deformation of pure copper and of internally oxidized Cu-0.09 wt% Al alloy was studied. Single crystals of different orientation were grown from pure copper and Cu-0.09 wt% Al rods, and the alloy crystals were internally oxidized. Tensile specimens were prepared from the crystals, and were irradiated to a neutron fluence of 5.5x1019 n/cm2 (E > 1 MeV) at a temperature below 700C. All control and irradiated specimens were tensile-tested. The addition of second-phase particles was found to have considerable effect on the deformation of irradiated copper. The increase in resolved critical shear stress was less in internally oxidized Cu-0.09 wt% Al (Cu-Al2O3) than in pure copper, while the change in ultimate shear stress and shear strain was much less. Yield point phenomena appeared in all crystals, but the drop in shear stress at the yield point was less in Cu-Al2O3. Two values of work-hardening coefficient (n) appeared in all unirradiated crystals, the first, a slightly larger one, was substantially decreased by irradiation, while the second was nearly unchanged. The decrease in n by irradiation was considerably larger in Cu-Al2O3. (orig.)