Mechanism of Suppressed Void Swelling in Bcc Multi-Component Alloys

Using a high dose Au-ion irradiation and transmission electron microscope, the void swelling in a novel bcc reduced activation multi-component alloy FeCrV was investigated. Compared to α-Fe, FeCrV has a stronger suppression effect on void swelling, showing a narrow distribution of smaller voids. Considering void swelling results from the aggregation of the mobile vacancies produced by displacement collisions, the migration of vacancies was investigated based on ab initio calculations. Migration energies and minimum energy paths of vacancies in FeCrV show after several zigzag steps the vacancies soon fall into intrinsic two-location traps, making the migration of vacancies locally dragged, which contributes to suppressed void swelling. The vacancy formation energies show local energy minimums commonly exist in Fe-rich and Cr-poor environments, which are potential two-location traps.