Effect of sinks on defect formation and dislocation loop growth in α-zirconium

Abstract

Using 3MeV proton beam irradiation on Zircaloy-2 alloy, a majority of dislocation loops near grain boundaries was identified as a-type vacancy loops by in situ transmission electron microscopy (TEM). To explain such unbiased residual defects distribution, we perform molecular dynamics simulations of collision cascade in α-Zr for the volume having various defects. The post-cascade population as well as distribution of residual defects are analyzed after a quenching stage while at the beginning of an annealing stage. Our results show that a-type dislocation loops are unbiased cascade sinks for irradiation-induced point defects, and c-component vacancy loops show weak sink ability to self-interstitial atoms (SIAs). However, c-component interstitial loops and tilt grain boundaries are strong cascade sinks for vacancies and SIAs, respectively. Further the absorption of a-type dislocation loops in the grain boundaries can be accelerated with a help of cascade-induced defects.