Effects of alloying elements on the solubility, diffusivity, and permeability of hydrogen in TiC from first-principles calculation

• The trigonal site of H in TiC is thermodynamically more stable. • The alloying of Zr, Nb, Ta, and W in TiC should reduce the hydrogen permeability. • The influence of alloying elements on the solubility and diffusivity of H in TiC is discussed. First-principles calculations were utilized to explore the effects of Zr, Nb, Ta, and W on the solubility, diffusivity, and permeability of hydrogen in TiC. It is found that the trigonal site of H in TiC, which is encircled by three Ti atoms lying a {111} plane, has been identified as thermodynamically more stable. The addition of alloying elements will destroy the equilibrium distribution of the Ti-H interaction and reduce the structural stability of interstitial H. Furthermore, the solubility, diffusivity, and permeability of H in Ti 32 C 32 and Ti 31 MC 32 (M = Zr, Nb, Ta, and W) at finite temperatures are derived, and the results are discussed and compared with similar experiments in the literature. Drawing upon the influence of elemental alloying on H retention, we deeply understand experimental observations and provide experimentalists with a potentially valuable recommendation for controlling hydrogen permeability.