Suppressed radiation damage by alloying elements mixture: a demonstration in V-Nb-based multi-principal element alloys

Ion irradiation effects are comparatively investigated in V-Nb-based alloys (V-xNb, x = 0–100 at.%) and an equiatomic VNbTaTi quaternary alloy. The smallest defect size and highest defect density are observed in V-50Nb in the binary system. This nonmonotonic composition dependence suggests an important role of compositional mixing rather than certain element additions on the irradiation response. Notably, despite smaller lattice distortion than V-50Nb, VNbTaTi exhibits superior irradiation tolerance, with suppressed irradiation defect formation, aggregation, and hardening, which highlights more sophisticated roles of compositional complexity on irradiation response beyond simply enlarging lattice distortion.