Enhanced recombination suppresses the void swelling in bcc multi-component alloys

Abstract

Multi-component alloys, e.g., high-entropy alloys, exhibit excellent mechanical and radiation tolerance properties, making them potential candidate materials in nuclear applications. In this work, the void swelling in a single-phase body-centered cubic (bcc) reduced activation multi-component alloy FeCrV under high dose Au-ion irradiation was investigated. It is found that FeCrV has a significantly suppressed void swelling compared to α-Fe, with voids of smaller size distributed in a narrower region. To understand the difference between these two alloys in the defect evolution and its possible effect on the void swelling, the diffusion of point defects in α-Fe and FeCrV was investigated. Combined Density Functional Theory (DFT) and kinetic Monto Carlo (kMC) method based on the environment-dependent vacancy migration energies was used to simulate the vacancy diffusion. It is shown that vacancy diffusion is enhanced, which is because vacancies prefer to migrate through the easy migration channels which have lower values of the wide migration energy distribution in multi-component alloys. Ab initio molecular dynamics (AIMD) was employed to simulate the interstitial diffusion. The results show the interstitial diffusion is sluggish in FeCrV due to the atomic traps existing that slow down interstitials’ migration. The migration process of point defects in bcc multi-component alloy shows clear chemical environment dependence. The closer mobilities of vacancies and interstitials enhance the local recombination of point defects and suppress the void swelling.