Effects of pre-existing vacancy-type dislocation loop on the irradiation resistance in FeNiCoCrCu high-entropy alloy

Abstract

Several high-entropy alloys (HEAs) show considerable promise as structural materials for nuclear energy applications, owing to their exceptional mechanical properties and radiation resistance. However, there is limited understanding of how pre-existing dislocation loops in these HEAs influence their radiation resistance. This study employs molecular dynamics (MD) simulations to investigate the influence of pre-existing dislocation loops on the irradiation resistance of FeNiCoCrCu HEA, focusing on the evolution of point defects, the formation of defect clusters, and the interactions between dislocation loops and point defects during irradiation process. Consequently, the interaction between irradiation-induced point defects and pre-existing dislocation loops leads to an increase in the number of point defects and defect clusters. This is attributed to the reduction in formation energy of point defects by the dislocation loop, which promotes their generation and alters their distribution, thereby inhibiting recombination between them. Point defects migrate toward the dislocation loop under stress field interactions, with the loop exhibiting preferential absorption of interstitial atoms over vacancies, serving as predominant sinks for defect accumulation. Furthermore, the presence of dislocation loops mitigates elemental segregation. During irradiation, dislocation loops absorb vacancies via positive climb and interstitials via negative climb. Meanwhile, the position and shape of the dislocation loop undergo changes, and its length increases. Notably, the FeNiCoCrCu HEA demonstrates enhanced resistance to pre-existing vacancy loop interactions compared to pure Ni, as evidenced by fewer irradiation-induced defects and reduced dislocation loop evolution post-irradiation. These findings elucidate the intricate interplay of defect dynamics in irradiated HEAs and provide critical insights for designing radiation-tolerant HEA systems.