Investigating the impact of alloying elements on hydrogen diffusion in Ti-based alloys via first-principles calculations

The diffusion of hydrogen in Ti-based alloys can lead to localized degradation of mechanical properties, resulting in hydrogen embrittlement. Therefore, identifying alloying elements that impede hydrogen diffusion is a crucial approach to mitigating hydrogen embrittlement and stress corrosion in Ti-based alloys. Utilizing first-principles calculations, we investigated the effects of 33 alloying elements on hydrogen diffusion in Ti-based alloys, including diffusion barriers and coefficients. Our findings demonstrate that elements such as Al, Ga, Si, and Zn increase the hydrogen diffusion barriers and decrease the diffusion coefficients in Ti-based alloys, thereby mitigating hydrogen embrittlement. It is revealed that the difference of electronegativity of Al, Si, Au, Ag, Pd, Ir, Zn, and Cu affects the hydrogen atom trapping ability. It also sheds light on strategies to mitigate hydrogen embrittlement in Ti-based alloys. This insight highlights their significant role in hindering the movement of hydrogen atoms within the alloys.