Effect of Cr content on microstructure evolution and hardness of high temperature irradiated-(TiZrNbTaCr)C high-entropy carbide ceramics

(TiZrNbTaCr)C ceramics irradiated by Au ion at 500 °C were investigated to reveal the effects of Cr element on the irradiation resistance of high-entropy carbides. Microstructural evolution indicates that the dislocation loop size decreases from ∼35 nm to ∼10 nm, while the defect density increases with increasing Cr content. Based on the migration energy change of C-related defects calculated by density functional theory (DFT), Cr addition favors increasing the migration energy of C interstitials and decreasing that of C vacancies. Thus, the growth of dislocation loops formed by C interstitials is inhibited, leading to defects with smaller size and higher density. Finally, nanoindentation test is conducted to uncover the influence of irradiation on the hardness of the samples. The hardness increment decreases with increasing Cr content, associated with the defect clusters induced by irradiation. This work proves that high-entropy carbide ceramics are potential candidates for advanced nuclear systems.