Tailoring the radiation tolerance of eutectic high-entropy alloy via phase-composition control

Eutectic high-entropy alloys (EHEAs) take advantage of heterogeneous crystal structures, numerous interfaces, and multicomponent composition designs, implying a potential radiation tolerance in the nuclear environment. In this work, we employed the He ion irradiation to study the irradiation behavior of two types EHEAs (Fe₄₂Ni₃₁Al₁₇Cr₁₀, abbreviated as Fe42, and Fe₄₇Ni₂₆Al₁₇Cr₁₀, abbreviated as Fe47) with different phase designs. The results showed that the FCC + B2 constituted Fe42 EHEA and BCC + B2 constituted Fe47 EHEA retained their general phase-composition features up to ∼ 1.2 dpa at 1073 K, while the long-range order of B2 phase was slightly disrupted in both alloys and more severe in the Fe42 EHEA. The quantification on He bubbles formation in different phases further indicated that the ordered B2 phase in Fe47 EHEA has a superior radiation resistance with smaller bubble size and less population. The differences in phase compositions and structures were believed to influence the vacancy-mediated helium diffusion during irradiation, which can account for the He bubble behaviors in the two kinds of alloys. The analysis on the width of bubble denuded zone along the phase boundary further suggested a higher energy barrier for the vacancy migration in the B2 phase, which consistently supported our inference on the underlying mechanism of bubble formation resistance of Fe47 EHEA. We believe that this work will provide a new strategy for designing EHEAs with excellent resistance to irradiation at elevated temperatures.