A computational study of dislocation evolution and radiation-induced segregation at a grain boundary

Abstract

Radiation-induced segregation (RIS) influences the chemical and mechanical properties of the structural materials of fusion and fission reactors. In this study, such RIS and dislocation sink strength evolution were investigated on the basis of computer simulation for solute segregation at and near a grain boundary. A new continuity equation model for RIS, based on the rate theory, which includes the simultaneous evolution of faulted dislocation loops and network dislocations, has been developed. A di-interstitial was assumed to be the nucleus of a dislocation loop in the present work, and we calculated dislocation evolution due to absorption of interstitials and vacancies. The dependencies of irradiation temperature, irradiation rate and dose on the RIS at a grain boundary under electron irradiation in high-voltage electron microscope (HVEM) were clarified. We also considered the effect of probe size used in TEM-EDS analysis in order to satisfy the relationship with measured compositional profiles. The present work sheds a light on the accomplishment of performing ‘combined calculation’ which deals with both RIS and various kinds of internal sink evolution.