Atomic scale structure dominated FCC and B2 responses to He ion irradiation in eutectic high-entropy alloy AlCoCrFeNi2.1

Abstract

Radiation-tolerant materials are widely desired in nuclear reactors. High-entropy alloys (HEAs) exhibiting superior mechanical performance and swelling tolerance are being considered as next-generation nuclear structural materials. However, an understanding of HEAs irradiation tolerance at an atomic scale is still lacking. In this study, the atomic scale irradiation response of AlCoCrFeNi2.1, composed of face-centered cubic (FCC) phase and B2 phase, has been systematically investigated at 298 and 723 K. The bubble volume ratio of the B2 phase is much larger than that of the FCC phase under the same irradiation conditions, and hence, the FCC phase has superior swelling tolerance than the B2 phase. Also, order-disorder transformation occurred in both L12 and B2 phases. The different irradiation responses between the FCC and B2 phases, depend firstly on composition and secondly on crystal structure. The higher compositional complexity and complicated atomic-level lattice environment of the FCC phase contribute to better radiation performance than B2 phase. The results pave a way for exploring radiation-tolerant structural high-entropy alloys.