Atomistic study of hydrogen distribution and diffusion around a {1 1 2}<1 1 1> edge dislocation in alpha iron

Despite extensive investigations, the distribution of hydrogen around a stress singularity field is still not well understood. In this study, we conducted molecular statics (MS) analyses of the hydrogen-trap energy around a {1 1 2}<1 1 1> edge dislocation in alpha iron. The distribution of hydrogen in crystals is generally assumed to be dominated by hydrostatic stress. However, the MS results indicate that the hydrogen-trap energy is sensitive to shear stress as well as hydrostatic stress, thus indicating that strong trap sites are distributed across a wide range on the slip plane around the dislocation core. We also performed molecular dynamics simulation of hydrogen diffusion, and revealed the anisotropic diffusion behaviour of hydrogen around the dislocation core.