Structural and mechanical responses of (ZrTiNbTa)C4 and ZrC ceramics under energetic He-ions irradiation

High entropy ceramics are potential structural materials for advanced reactor concepts where numerous helium atoms would be produced due to the (n, α) nuclear transmutation reaction. However, the irradiation behaviors of high entropy ceramics is not well understood until now. In present work, the responses of high entropy (ZrTiNbTa)C4 and its binary constituent ZrC ceramics to energetic He-ions irradiation have been studied. X-ray diffraction analysis showed that He-ions irradiation resulted in peak shift and broadening of diffraction peaks in both (ZrTiNbTa)C4 and ZrC, which denotes lattice expansion and structural damages induced by the irradiation. Transmission electron microscope observation revealed that spherical helium bubbles distribute uniformly in the grain interiors of (ZrTiNbTa)C4 while "string-like" bubbles with a preferred orientation are observed in ZrC grains. Nanoindentation characterization gives that the irradiation induced hardening of (ZrTiNbTa)C4 is less definite than that of ZrC. The irradiation mechanisms of high entropy ceramics have been discussed.