Defect energetics and stacking fault formation in high-entropy carbide ceramics

Inspired by the concept of entropy stabilization, multicomponent transition metal carbide (MTMC) ceramics have received increasing attention due to their extraordinary performances. However, the role of partial disorder in the transition metal sublattice on the defect properties in MTMCs is still elusive. In this work, we study defect formation and generalized stacking fault energies (GSFEs) in MTMCs. In both cases, we compare the results in MTMCs to binary TMCs. Our results suggest that C-related defects generally exhibit lower formation energies in MTMCs, suggesting that MTMCs are prone to off-stoichiometry with C vacancies. We further show that lower formation energies of C interstitials and higher migration energies of C vacancies account for the experimentally-observed delayed defect evolution. Finally, our calculated GSFEs in different MTMCs are close to the averages from all the constituent binary TMCs, indicating that the rule of mixture (ROM) can be applied to estimate the stacking fault energies for stoichiometric MTMCs.