Irradiation behaviors of two novel single-phase bcc-structure high-entropy alloys for accident-tolerant fuel cladding

Abstract High-entropy alloys (HEAs) are potential alternative materials for accident-tolerant fuel cladding due to their excellent irradiation resistance and high-temperature corrosion resistance. In this work, two novel body-centered cubic (bcc) structured Mo0.5NbTiVCr0.25 and Mo0.5NbTiV0.5Zr0.25 HEAs were fabricated. Helium-ion irradiation was performed on the two HEAs to simulate neutron irradiation, and the crystal structure, hardness, and microstructure evolution were investigated. The crystal structure of the Mo0.5NbTiVCr0.25 HEA remained stable at low fluences, while amorphization may occur at high fluences in the two HEAs. The irradiation hardening value of the Mo0.5NbTiVCr0.25 was 0.77 GPa at fluences of 1 × 1017 ions/cm2 and 1.49 GPa at fluences of 5 × 1017 ions/cm2, while the hardening value of the Mo0.5NbTiV0.5Zr0.25 was 1.36 GPa at ion fluences of 5 × 1017 ions/cm2. In comparison with most of the conventional alloys, the two HEAs showed slight irradiation hardening. The helium bubbles and dislocation loops with small size were observed in the two HEAs after irradiation. This is the first time to report the formation of a dislocation loop in bcc-structure HEAs after irradiation. However, voids and precipitates were not observed in the two HEAs which could be ascribed to the high lattice distortion and compositional complexity of HEAs. This research revealed that the two HEAs show outstanding irradiation resistance, which may be promising accident-tolerant fuel cladding materials.