Fluctuations in stacking fault energies improve irradiation tolerance of concentrated solid-solution alloys

Abstract

Concentrated solid-solution alloys (CSAs) have stimulated great interest over recent years because of their excellent mechanical properties and irradiation tolerance. However, since their compositional space can be tuned vastly by varying elemental species and concentrations, it is of great significance to explore the relationship between their mechanical and irradiation performance with their intrinsic properties. In this work, we show that there is a link between the irradiation resistance of CSAs and the fluctuations in their intrinsic stacking fault energies (SFEs). Based on four CSA systems with distinct SFE properties, we find that large fluctuations in SFE distributions, together with the unique heterogeneity of defect diffusion process, can effectively suppress defect number and defect cluster growth under accumulated cascade conditions. We further demonstrate that the reason responsible for the enhanced damage tolerance is that the fluctuations in SFE distributions can effectively impede dislocation movement by increasing the onset stress required for dislocation motion. Our results thus provide evidence that the improved mechanical and irradiation properties of CSAs can be predicted by monitoring their intrinsic SFE characteristics.