| Abstract Scope |
High-entropy or compositionally complex ultra-high temperature ceramics (UHTCs) may have improved or tuneable properties. In particular, MC1-x carbides have been the source of significant interest in recent years, but systematic experimental exploration is prohibitively expensive and time consuming due to the number of components.
Despite individually having similar properties and behaviour, there is complex local behaviour in the mixed cation carbides. At high temperatures, the configurational entropy is thought to overcome any opposing enthalpic effects inhibiting mixing, however, there remains significant structural distortion and huge variations in bond strengths resulting from the local atomic environment. Although the thermodynamic stability can determine whether or not a mixture is a single phase at equilibrium, variations in the local structure may affect other features such as mechanical properties and oxidation rates.
This work uses first-principles calculations to understand the thermodynamics and local properties in MC1-x (M=Ti,Zr,Hf,Nb,Ta) mixtures at different carbon stoichiometries. |