Atomistic insights into the irradiation response and mechanical properties of FeCrNiAl high-entropy alloys

FeCrNiAl high-entropy alloys (HEAs) have emerged as promising structural materials for nuclear applications due to their exceptional radiation resistance. This study employs molecular dynamics simulations to investigate the atomistic mechanisms underlying their irradiation tolerance, focusing on the influence of Fe content. The results reveal that the equiatomic FeCrNiAl HEA exhibits superior radiation resistance compared to non-equiatomic hvariants (Fe 0.5 CrNiAl and Fe 0.25 CrNiAl HEAs). This advantage stems from enhanced defect recombination facilitated by elevated temperatures during cascade collisions. Nickel interstitials and Aluminum vacancies dominate the defect populations due to their low formation energies. Furthermore, the dual-phase equiatomic FeCrNiAl HEA demonstrates even better irradiation resistance than its single-phase counterpart. The introduction of the B2 phase increases the material's cohesive energy, and the fully coherent BCC/B2 interface further improves performance. The increased cohesive energy raises the displacement threshold, while the distorted stress field and energy traps at the coherent interface capture defects and promote recombination. Nanoindentation tests show that low irradiation doses produce minimal radiation hardening, as they mainly generate isolated point defects that have little effect on dislocation nucleation. These findings provide critical insights into the radiation damage behavior of FeCrNiAl HEAs.