Radiation-induced Fe segregation in the dual-phase FeCrNiMnAl high-entropy alloy under high-dose helium ion irradiation.

• Unveiled Fe segregation at HEA phase boundaries under high helium doses. • Demonstrated novel insights into radiation-enhanced diffusion mechanisms. • Employed advanced STEM and EDS to elucidate microstructural changes. • Revealed the segregation dynamics in FeCrMn with metastable FCC structure. This study investigates the radiation-induced Fe segregation in the dual-phase FeCrNiMnAl high-entropy alloy (HEA) under the helium (He) ion irradiation with a dose of 5 × 1017 ions/cm2. The superior bubble swelling resistance of the chemical-ordered NiAlMn phase with B2 structure is observed compared to the FCC FeCrMn matrix, which can be attributed to their differences in atomic packing factors. Fe segregation at phase boundaries (PBs) is detected after irradiation, as evidenced by a higher concentration of Fe at PBs than in the matrix by about 10 at.%. This phenomenon can be ascribed to the migration of Fe interstitials induced by irradiation cascades and the punching mechanism during bubble growth. In essence, the Fe segregation in this study is driven by the radiation-enhanced diffusion and metastable state of FCC-structured FeCrMn with supersaturated Fe atoms. These insights provide theoretical foundations and innovative perspectives for the radiation-induced segregation (RIS) in HEAs. [ABSTRACT FROM AUTHOR]