Microstructures, mechanical properties, and irradiation tolerance of the Ti–Zr–Nb–V–Mo refractory high-entropy alloys

High-entropy alloys (HEAs) have shown a good application prospect in the structural components of advanced nuclear reactors due to their impressive high-temperature performance and irradiation tolerance. This study aimed to design and prepare the body–centered cubic–structured Ti2ZrNb, Ti2ZrNbV0.5, and Ti2ZrNbV0.5Mo0.2 HEAs, consisting of low-thermal neutron absorption cross-section elements, for obtaining accident-tolerant fuel (ATF) cladding materials. The microstructures and mechanical properties of the Ti–Zr–Nb–V–Mo HEAs irradiated to a fluence of 6 × 1016 ions/cm2 at 1023 K were investigated to explore the irradiation tolerance under He ion flux. The results indicated that the growth of the He bubbles in the Ti–Zr–Nb–V–Mo HEAs decreased with an increase in the component number. This was consistent with previous findings on the HEAs with face-centered cubic structures and could provide an understanding of designing high-performance HEAs under irradiation. The Ti–Zr–Nb–V–Mo HEAs showed lower irradiation hardening fraction than most reported conventional materials, especially for the Ti2ZrNb (17.3%) and Ti2ZrNbV0.5Mo0.2 HEAs (23.6%). The Ti2ZrNbV0.5Mo0.2 alloy possessed an optimal combination of irradiation hardening resistance, structural stability, and comprehensive mechanical properties at room and elevated temperatures, which might make the novel HEA a promising candidate for the ATF cladding materials.