First‐Principle Prediction of Hydrogen Diffusion Path in Titanium Alloy Passivation Film

The interaction energy between hydrogen atoms and pristine TiO 2 passivation films, as well as three different defective passivation films, and the diffusion process of hydrogen atoms on the surface of these passivation films are studied using molecular dynamics methods. The calculation results show that the interaction energy between H atoms and V Ti defective passivation film is the strongest, which is −10802.43222 kcal mol −1 . The interaction energies between H atoms and V O defect and V Ti‐O defect passivation films are −3963.95918 and −3966.21759 kcal mol −1 , respectively. The diffusion coefficients of H atoms in V Ti defect, V O defect, and V Ti‐O defect passivation films are 14.88 × 10 −5 , 16.10 × 10 −5 , and 5.69 × 10 −5 cm 2 s −1 , respectively. By investigating the self‐diffusion properties of hydrogen in pristine and three different defective passivation films, the anisotropic diffusion behavior and characteristics of hydrogen in passivation films with different defect structures are discovered. The main path of hydrogen diffusion under different defect structures is predicted, which provides a theoretical basis for the prediction of hydrogen‐induced cracking and the development of early warning technology for passivation film surface failure.