Stability, mechanical, and thermodynamic behaviors of (TiZrHfTaM)C (M = Nb, Mo, W, V, Cr) high-entropy carbide ceramics

Multicomponent high entropy carbide ceramics (HECCs) have drawn increasing attention because of their potential applications as ultra-high temperature and super-hard materials. In this work, the stability, mixing behavior, mechanical, and temperature-dependent properties of rock-salt (TiZrHfTaM)C (M = Nb, Mo, W, V, or Cr) HECCs were first systematically investigated by density functional theory (DFT) and DebyeGruneisen model methods. The five HECCs are thermodynamically stable owing to the negative formation enthalpies and cohesive energies. They could form the single-phase high entropy solid solution ceramics, owing to the evaluation of atom size and lattice differences, as well as mixing enthalpy criteria. Except for the system containing Cr, the others have already been confirmed by experimental findings. Among these, (TiZrHfTaNb)C most readily forms homogeneous solid solution phase, and is the most stable, brittlest, and hardest HECC material. Significantly, (TiZrHfTaV)C behaves slightly better than (TiZrHfTaNb)C with increasing temperature, owing to the comparable bulk modulus and Debye temperature, smaller volumetric expansion, and lower anharmonic effects. This work provides the instructive information for predicting and designing the high-performance ultra-high temperature ceramic materials applicable in extreme environments. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, the stability, mixing behavior, mechanical, and temperature-dependent properties of multicomponent high entropy carbide ceramics (HECCs) were systematically investigated. It was found that one of the HECC materials exhibited better performance at different temperatures, providing instructive information for predicting and designing high-performance ultra-high temperature ceramic materials.