On the Room-Temperature Mechanical Properties of an Ion-Irradiated TiZrNbHfTa Refractory High Entropy Alloy

Refractory high-entropy alloys (RHEAs) are potential candidate materials for use in next-generation nuclear reactors due to their excellent mechanical performance at high temperatures. Here, we investigate the microstructure and mechanical properties of the nanocrystalline RHEA TiZrNbHfTa before and after irradiation with He2+ ions to determine radiation-induced property changes. Using nanoindentation and in situ microtensile testing we find only small changes in hardness after irradiation but a significant increase in yield and ultimate tensile strength without loss in ductility. This is associated with radiation hardening and a shift from shear localization failure with smooth fracture surfaces to a fracture morphology consisting of fine dimples and intergranular failure characteristics. Overall, the material shows excellent damage-tolerant properties with good combinations of strength and ductility both prior to and after ion irradiation