Compositional and structural origins of radiation damage mitigation in high-entropy alloys

The ability of high-entropy alloys to resist radiation damage is rooted in their compositional complexity and associated high configurational entropy. In addition, grain boundaries within all alloys serve as effective sinks for defects. Using atomistic modeling, we investigated defect-grain boundary interaction mechanisms near ordered and amorphous grain boundaries in pure nickel and in a model, quaternary, high-entropy alloy (FeCoCrNi). Our results demonstrate that a combination of compositional complexity with amorphization of the grain boundary leads to much more efficient recombination and annihilation mechanisms. Coupling these two microstructural features results in the lowest amount of residual damage, indicating that these effects compound to increase radiation tolerance. These observations are rooted in locally dependent defect migration barriers in the high-entropy alloy and the strong trapping at both ordered and amorphous grain boundaries.