Analysis of the Factors That Cause Unstable Deformation and Loss of Plasticity in Neutron-Irradiated Copper

Abstract

Copper is used as an example to analyze the effect of radiation on the stress-strain curves and deformation stability of radiation-hardened metals. The analysis is based on an equation that describes the evolution of the dislocation density with deformation in a plastically deformed material. Deformation instability in the initial stage of the stress-strain curve is caused by strong deformation localization at the microscopic level as a result of the transformation of immobile radiation defects (vacancy and interstitial loops) into mobile dislocations. The channeling of a large number of dislocations along slip planes causes the appearance of a yield drop and a yield plateau in the stress-strain curves. The critical conditions for their appearance, as well as the theoretical irradiation-dose dependences of the yield-plateau length and the uniform strain to necking, are found.