Revealing the governing factors for long-term radiation damage evolution in multi-principal elemental alloys through atomistically-informed cluster dynamics

Multi-principal elemental alloys (MPEAs) exhibit unusual mechanical properties and irradiation resistance. It has been reported that the irradiation tolerance of MPEAs originates from the long-term defect evolution stage rather than the ballistic collision phase. However, understanding the long-term evolution of MPEAs is exceptionally challenging due to intrinsic chemical disorder. In this work, we apply atomistically-informed cluster dynamics to study defect evolution in MPEAs for the first time, which enables us to elucidate the critical features responsible for the irradiation performance of MPEAs. With suitable irradiation parameters, our obtained cluster size distributions are in good agreement with experiments. We further discuss the influences of defect migration energy heterogeneity, cluster geometry, and temperature on the produced defect cluster forms. Our results suggest that the small clusters during the collision phase in MPEAs suppress the formation of large-sized defect clusters in the long term. Contrary to the common belief, a broader migration energy distribution due to chemical disorder cannot reduce the maximal defect cluster size but increase the proportion of small clusters. Our results thus reveal that the major role of chemical complexity in MPEAs is to modify the growth mechanism of clusters by promoting small cluster formation and suppressing overall defect diffusivities.