Abstract Scope |
High-entropy or multi-principal component ultra-high temperature ceramics, including the rocksalt structured MC1-x (where M is an equiatomic or non-equiatomic mixture of metallic elements including Ti, Zr, Hf, Nb, and Ta), have recently generated significant interest due to their potential tuneable properties such as melting point, hardness, ductility, and oxidation resistance. The single metallic element carbides are known to have a wide range of stoichiometry facilitated by significant numbers of carbon vacancies that have a tendency towards low temperature ordering, with different trends observed in group IV and group V transition metal carbides. This work uses first-principles calculations to locate miscibility gaps in the multi-principal component carbides with and without carbon vacancies present, and to explore the effects of atomic mixing on the metal lattice on the vacancy ordering in high entropy carbides. The thermodynamic and structural properties, local atomic environment, and atomic bonding features are used to identify trends. |