| Abstract Scope |
High-entropy or multi-principal component ultra-high temperature ceramics (UHTCs), such as MC1-x carbides (where the cation M=Ti,Zr,Hf,Nb,Ta), may have potential improved or tuneable properties such as melting point, hardness, ductility, and oxidation resistance. At high temperatures, the configurational entropy in these multi-principal component mixtures is thought to overcome any opposing enthalpic effects inhibiting mixing, resulting in single solid solution phases. However, despite the individual group IV and V transition metal carbides having similar properties and behaviour on an atomic or electronic scale, the elemental differences result in the high entropy ceramics having complex local behaviour that depends on the local atomic environment. This work uses modelling approaches including density functional theory (DFT) calculations and CALPHAD (phase diagram) modelling to explore the MC1-x (M=Ti,Zr,Hf,Nb,Ta) composition space spanned by these systems, including variations in number and ratio of transition metal elements as well as carbon vacancy concentration. |