Recovery of copper alloys after neutron irradiation at low temperatures

Abstract

The effects of fast neutron irradiation near 4.2°K on dilute Cu, Cu₃Au, α-CuZn, β-CuZn and CuNi alloys were studied by electrical resistivity measurements. For Cu₃Au, the recovery stage at ∼ 100°K becomes more distinct with increasing long-range order, and is attributed to migration of interstitials. The ratio of the number of replacements to the number of displacements (C _R /C _F ) is estimated to be about 50 for neutron irradiation, in contrast to the previously reported value of ∼2 for electron irradiation. For α-CuZn, a large recovery stage at ∼150°K is found and attributed to annihilation of interstitids whose migration produces ordering. For β-CuZn, migration of interstitials also produces ordering. It is also suggested that in β-CuZn, the ratio C _R /C _F is larger for neutron irradiation than for electron irradiation as in the case of Cu₃Au. The results on CuNi alloys are presented without explanation.