Non-dilute multicomponent alloys, or compositionally complex alloys (CCAs), is a promising materials class for components in fusion reactors as well as next-generation fission reactors. In some CCAs, nanoscale domains of local chemical order (LCO) have been observed despite microscale single-phase homogeneity. Because LCO can alter point defect diffusion barriers, they may also provide sites for accommodation of defects under irradiation. In this proposal, we seek to investigate the effect of LCO domains on defect mobility and accommodation as well as the effect of irradiation damage on the stability of these domains for three alloy classes in varied ion species environments. Ion species variation will target selective vacancy immobilization, changing the migratory point defect landscape of the alloy. This project leverages the unique capabilities of the University of Michigan Ion Beam Laboratory to detect real-time chemical information during in situ irradiation experimentation. This approach will provide novel insights into the role of LCO of varied domain constituency in CCAs, aimed towards tuning chemically ordered features that contribute to residual radiation damage reduction.

The mechanisms by which HEAs, particularly varied chemically ordered phases within HEAs, respond dynamically to radiation damage are not well understood. Such inquiries of defect morphology and dynamic structural domains are highly relevant to the near-term goal of the DOE to “harness dynamic interfaces and mitigate degradation of materials for fission and fusion reactors” as declared in the BES Roundtable on Foundational Science to Accelerate Nuclear Energy Innovation in 2022. The role of interfaces on radiation damage evolution is critical to understanding material tolerance and has been extensively demonstrated in work output by the Energy Frontier Research Center: Fundamental Understanding of Transport Under Reactor Extremes program. From prior results we assert that the structural landscape of a RHEA in a radiation condition is more complicated than previously anticipated, particularly in a condition that mimics transmutation impacts. By characterizing the evolutionary properties of dynamic structures, we hope to gain insight towards tuning chemically ordered features to contribute to residual radiation damage reduction.