Computational Search for Compounds with the Highest Melting Temperature in the Ternary HfC‐Based Ceramics

The melting temperature ( T m ) determines the service temperature of ultrahigh‐temperature ceramics (UHTCs), so it is of great significance to search for compound with the highest T m in UHTCs. In present work, the formula to calculate the T m of UHTCs with the rock salt structure is modified first: T m = f ( c ) EV m /(100 k B ), f ( c ) = 0.6412* c + 0.9947, which considers the influence of vacancy concentration ( c ) on the T m . The calculated T ms are in good agreement with the experimental values of UHTCs, and the calculation accuracy exceeds 91%. The T m could be obtained by only calculating the elastic modulus and volume per atom. Using this formula, the T ms of ternary HfC‐based UHTCs with the rock salt structure are predicted, and a new compound with the highest melting temperature, HfTa 2 C 3 , is found. Finally, the empirical relationship between the T m and shear modulus or Vickers hardness of UHTCs with the rock salt structure is also investigated.