The d band center as an indicator for the hydrogen solution and diffusion behaviors in transition metals

Understanding the hydrogen solution and diffusion behaviors are crucial to design the hydrogen embrittlement resistant structural materials in industry applications. Whether there exists an indicator for prediction of the hydrogen solution and diffusion behaviors is an important but unclarified question. In this study, the hydrogen solution and diffusion behaviors in transition metals and alloys were investigated by density functional theory (DFT) and nudged elastic band (NEB) method calculations. The calculation results reveal that the d band center is directly correlated with hydrogen solution ability in structural materials. The strain and alloying effects on the variations of hydrogen solution energy and d band center have also been considered and the well variation consistency between them is established. With respect to the hydrogen diffusion in transition metals, the transition state has a lower d band center than the initial state. Especially, the hydrogen diffusion energy barrier is proportional to the d band center difference between the initial state and transition state in alloying Fe. Thus the d band center can be regarded as an indicator for hydrogen solution and diffusion in structural materials, which can enlighten us to design the structural materials with high hydrogen embrittlement resistance.