Understanding hydrogen diffusion mechanisms in doped α-Fe through DFT calculations

Hydrogen embrittlement is detrimental to structural metals during applications. Herein, we explore the hydrogen diffusion mechanisms in doped α-Fe using first-principles calculations. We prove that the hydrogen trap is a thermodynamically spontaneous process, and doping will decrease the hydrogen adsorption energy due to the change of adsorption sites. Furthermore, hydrogen diffusion from surface to subsurface will determine the diffusion rate. Mo, Mn and C are beneficial to the increase of the energy barrier of hydrogen diffusion from the surface to subsurface and in the bulk. The current work provides a promising path towards enhancing the hydrogen diffusion barrier in α-Fe.