Atomistic simulation of the effects of hydrogen on the mobility of edge dislocation in alpha iron

Atomistic models composed of alpha iron were analyzed to investigate the effect of hydrogen on the mobility of edge dislocations. The hydrogen distribution around an edge dislocation was accurately estimated based on the embedded atom method (EAM) and the energy barriers for edge dislocation notion were investigated using the nudged elastic band (NEB) method. It was observed that a stable hydrogen site existing around a specific edge dislocation in alpha iron was limited to the dislocation core and the exact slip plane around it. This suggests that the hydrogen distribution around the dislocation core does not agree with the theory of elasticity. Under low hydrogen conditions, a decrease in the energy barrier for dislocation motion was observed, which could contribute to the hydrogen enhanced localized plasticity (HELP) mechanism.