Influence of temperature and strain amplitude on damping and modulus of electron-irradiated copper

Abstract

The changes of damping and modulus in copper during 1.5 MeV-electron irradiation were measured at different strain amplitudes, measuring and irradiation temperatures. It was found that the minimum in dislocation pinning rate at 160°K reported by Thompson and Buck occurs only as function of the measuring temperature and not of the irradiation temperature. Furthermore, it was found that the depth of the minimum decreases strongly with decreasing strain amplitude and that also the differences in pinning rates derived from damping and modulus measurements are caused mainly by amplitude dependent effects. It is concluded that the minimum does not characterize the true pinning rate but is caused by a temperature and amplitude dependent damping effect. Hence also the interpretation that the minimum characterizes the thermal conversion of crowdions is no longer justified.