Effects of temperature on helium cavity evolution in single-phase concentrated solid-solution alloys

Single-phase concentrated solid-solution alloys (SP-CSSAs) have shown great potential as structural materials in advanced reactor systems. Up to date, nevertheless, the synergistic effect of compositional complexity and irradiation temperature on helium (He) irradiation-induced cavity formation has not been systematically studied yet. In this work, pure Ni and three prototype face-centered-cubic SP-CSSAs, i.e., NiCo, NiCoCr and NiCoFeCrMn, were irradiated with He⁺ ions at 673, 773, 873 and 973 K. The evolution of He-induced cavities were investigated in detail with transmission electron microscopy. It was found that growth of He cavities was suppressed with increasing compositional complexity at 673 and 773 K. Due to the lower melting temperature, NiCoFeCrMn exhibited the strongest temperature susceptibility in terms of He cavity growth with the increasing temperature. Interestingly, the He cavity growth tended to be enhanced with increasing compositional complexity when the radiation temperature increaseed to 973 K, which can be attributed to the prominent chemical-biased vacancy migration at high temperatures.