b'added complexity of multiple phases.ties that may vary drastically evenFigure 2. Defect cluster densities As such, single-phase alloy candidatesover relatively small atom percents.of FCC (left) and BCC HEAs (right) were selected for further study. Experi- High-throughput sample fabrication,compared to less compositionally complex reference materialsmental studies of radiation damageexperimentation, and CALPHAD mechanisms support the Departmentphase predictions were developed to of Energy (DOEs) objectives byaddress this problem, and support DOE enhancing the fundamental under- efforts to expediate nuclear materials standing of extended defect formationdiscovery, and to some extent qualifica-and growth which guides alloy designtion, to meet the increasing demands efforts and further modeling efforts.of future reactor designs.In addition to a damaging radiationAccomplishments:field, nuclear structural materials mustSeveral irradiation damage experiments perform at the intersection of corrosiveand the respective post-irradiation coolants and mechanical stresses, all atexamination were conducted byhigh temperature. The project set out toCalvin Parkin and supplemented by benchmark the mechanical propertiesother teammates:and thermal stability of selected alloys against other well-understood struc-A paper concerning high temperature tural materials, as well as the corrosionand cryo in-situ irradiations at the behavior in current and advancedIVEM-Tandem experiment at Argonne reactor coolants. HEAs present theNational Laboratory was published unique challenge of an extensivein Acta Materialia. In the cryogenic compositional space, with proper- irradiations, diffusion of point 2021|AFC ACCOMPLISHMENTS 105'