Atomic-scale mechanisms of He-induced dislocation loop growth in α-Fe from molecular dynamics simulations

Abstract

The interaction between helium (He) and irradiation damage is crucial for understanding the degradation mechanisms and performance of structural materials for fusion applications. However, the atomic-scale mechanisms underlying the helium influence on dislocation loop growth remain poorly understood. In this work, we investigated the interactions between He and interstitial dislocation loops in bcc iron using molecular dynamics simulations. It was found that the formation of He bubbles around dislocation loops enhances loop growth through the dislocation climb mechanism. An increased He implantation rate results in a higher growth rate of dislocation loops, with more He bubble nucleation on the loops leading to greater loop extension. Furthermore, the interactions between dislocation loops and immobile He bubbles contribute to loop enlargement through the dislocation loop absorption mechanism. Larger He bubbles induce a more substantial rise in loop length. These findings provide valuable insights into the atomic-scale processes by which He promotes dislocation loop growth in α-Fe, advancing our understanding of He-induced irradiation damage in fusion materials.