Mechanical and microstructural response of the Al_0.5CoCrFeNi high entropy alloy to Si and Ni ion irradiation

The nearly infinite compositional design space of high entropy alloys (HEAs) presents many opportunities to improve performance in extreme environments, particularly for nuclear reactors. The ability of some HEAs to resist high amounts of radiation damage, while well documented, has not yet been fully exploited. We studied the irradiation effect of different ions (Si and Ni) on the microstructure and mechanical properties of the Al_0.5CoCrFeNi alloy at its equilibrium state, and of the individual response of each phase to irradiation. The results show a stronger effect of Si ions and differences in response of the ductile FCC (A1) and brittle ordered BCC (B2) phases towards irradiation. This finding highlights the need to further probe unexplored compositional spaces in HEAs, as further optimization is likely to yield further compositional and microstructural stability with practical applications.