First-principles study on the hydrogen embrittlement resistance of CoCrFeMnNi high-entropy alloys

This study used first-principles calculations to investigate the dissolution and diffusion behavior of hydrogen in the CoCrFeMnNi high-entropy alloy, aiming to provide theoretical guidance for designing novel multi-principal element alloys with excellent hydrogen embrittlement resistance. The results suggest that hydrogen's average dissolution energy and volumetric expansion rate in the octahedral interstitials are lower than those in the tetrahedral interstitials, indicating that hydrogen prefers to occupy octahedral interstitials. Compared with the ideal octahedral interstitial, lower dissolution energy, and higher diffusion barrier were observed in the octahedral interstitials enriched with Cr and Co. Furthermore, the presence of hydrogen reduces the formation energy of vacancies, which act as hydrogen traps to capture H and provide additional diffusion channels to lower the diffusion barrier. Therefore, increasing the content of Cr and Co can effectively reduce the diffusion coefficient of hydrogen. In contrast, Fe, Mn, and Ni content has a relatively minor impact on the diffusion coefficient. These results provide a new perspective for understanding and developing novel multi-principal element alloys with excellent hydrogen embrittlement resistance.