Unveiling the interactions between preexisting dislocations and displacement cascades in the refractory high-entropy alloy WTaCrV

Refractory high-entropy alloys (RHEAs) represented by WTaCrV are excellent candidates for future nuclear reactor structures. Both the preexisting edge dislocations (EDs) and screw dislocations (SDs) can significantly impact the irradiation performance of RHEAs. To explore the influence of preexisting dislocations on the generation and evolution of irradiation point defects in the RHEA WTaCrV, the interactions between preexisting dislocations (including EDs and SDs) and displacement cascades are studied by molecular dynamics simulations in this work. In addition, the results of the RHEA WTaCrV without preexisting dislocations and of pure W with preexisting dislocations are included for comparison. It is found that the presence of preexisting dislocations leads to a significant increase in the number of remained point defects after the cascades. However, the absorption of vacancies by dislocation cores in the RHEA WTaCrV is more significant than that in the pure W. Therefore, preexisting dislocations can reduce the possibility of void formation and act as sites for recombination of vacancies and interstitials in the subsequent long-term evolution. For the preexisting EDs in the RHEA WTaCrV, the local pinning of EDs, the attraction of vacancies, and the severe lattice distortion jointly cause the bowing out of EDs, which is conductive to accommodate vacancies. For the preexisting SDs, the abundant cross kinks tend to bind vacancies or interstitials, promoting the motion of SDs as well as the annihilation of point defects. In this sense, the preexisting dislocations in the RHEA WTaCrV can significantly enhance the irradiation resistance. The results of this research can provide design guidance for regulating the anti-irradiation performance of RHEAs.