b'Nuclear Science User Facilities Radiation Damage in High-Entropy AlloysMohamed ElbakhshwanUniversity of Wisconsin, Madisonelbakhshwan@wisc.eduM our fundamental understanding of aterials in fast reactors are expected to withstand highirradiation effects in these multi-temperatures, damagingcomponent alloys and to assess their radiation levels, and corrosivepotential applications in future SFRs.environments for extended periods ofResultstime. They must be resistant to voidTwo high entropy alloys, swelling up to several hundreds of dpa,Cr 18.1 Fe 27.3 Mn 27.3 Ni 27.3 , and maintain adequate creep strength upCr 15 Fe 35 Mn 15 Ni 35 , along with reference to 650C, fracture toughness at 320C,materials (model Alloy 709, Ni, and and exhibit high levels of corrosionV) were irradiated at 500 C with resistance in liquid-sodium or liquid- 3.7 MeV self-ions Ni2+ to 50 dpa. The lead-alloy coolants. Therefore, theirradiations of FCC materials resulted deployment of sodium fast reactorsin the formation of perfect dislocation (SFRs) is, in part, limited by theloops against a dislocation network. development of materials that canThe average size of all loops is quite sustain these conditions [1]. High- similar, ranging from approximately entropy alloys (HEAs) are composed of13 to 20 nm in the longest dimension. four or more metallic elements mixedVoids (shown in Figure 1) were also in equimolar (or near to equimolar)found in Cr 15 Fe 35 Mn 15 Ni 35 , but not ratio to favor single-phase solid-solutionin Cr 18.1 Fe 27.3 Mn 27.3 Ni 27.3beyond the formation [2]. FCC HEAs based on 3ddamage peak predicted by the Stopping transition metals are characterized byand Range of Ions in Matter (SRIM), low stacking-fault energy; thus, theywhich supports the idea that interstitial deform by twinning, which increasesloops are generally less mobile with their dislocation-storage capacityincreased compositional complexity.and, hence, their ductility [3]. On the other hand, HEAs based on lightConclusionrefractory metals exhibit high strengthThe mobility of interstitial loops and limited softening up to very highdepends on the compositional temperatures [4]. These properties makecomplexity of the material, decreasing them potentially attractive candidatesas the complexity increases. In an for investigations as cladding alloysisotropic neutron-irradiation environ-in the extreme SFR conditions. Thement, the formation of dislocations, goal of this study is to understand thewhich are immobile even after microstructural changes inproposedunfaulting, may increase the sink HEAs under heavy ion irradiation tostrength and reduce the time needed evaluate its radiation damage to enhanceto form a supersaturation of vacancies and for voids to grow to larger sizes.62'