Irradiation response of microstructure and mechanical properties of NbMoVCr multi-principal element alloy coatings

In this study, NbMoVCr multi-principal element alloy (MPEA) coatings with near-equal atomic ratios were deposited onto the ferritic/martensitic (F/M) steel substrate by magnetron sputtering and then irradiated using 6 MeV Au2+ at room temperature (RT) and 550 degrees C, respectively. The results demonstrate that the NbMoVCr coatings have excellent irradiation resistance in terms of phase stability. RT-irradiation introduces both interstitial- and vacancy-type dislocation loops, and the dislocation loop density increases with the increase of irradiation damage dose. Meanwhile, RT-irradiation could also induce grain growth of the coating. However, under high-temperature irradiation, more recombination and annihilation of irradiation-induced defects, and recrystallization occur in the coating. In addition, irradiation also promotes the desegregation of V and Cr elements at the grain boundaries and enhances the uniformity of the distribution of coating elements. Irradiation softening and hardening in NbMoVCr coatings are also found to depend strongly on both irradiation damage dose and irradiation temperature. The creep deformation mechanism of the coating is dominated by diffusion; thus, the irradiation-enhanced diffusion reduces the creep resistance of the coating.