Indentation behaviour of ion-irradiated X-750 Ni-based superalloy

The mechanical properties of an ion-irradiated Ni-based superalloy have been evaluated using nano-indentation hardness tests. A high-energy Ni ion beam was employed for irradiation at room temperature up to different doses. Nano-indentation tests were carried out in the range of 100-1000 nm to measure hardness changes of the experimental alloy. The results show softening of the irradiated material compared to the un-irradiated material, with the softening being more pronounced at the higher dose. Cross-sectional transmission electron microscopy characterisation reveals that gamma'-precipitate instability (disordering/dissolution) is the main reason for the softening behaviour and this outweighs the hardening effect of irradiation-induced defects.