Discerning enhanced dislocation plasticity in hydrogen-charged α-iron nano-crystals

Novel atomistic simulations of α-iron nano-crystals starting with pre-existing dislocation networks have been performed to identify the effect of high hydrogen concentrations on enhanced dislocation plasticity. Hydrogen is shown to decrease the dislocations free-surface nucleation stress, as well as increase the flow strength of crystals. The dislocation density is observed to increase in the presence of hydrogen due to dislocation pinning and enhanced dislocation self-multiplications. Hydrogen also changes the deformation morphology from discrete slip planes in hydrogen-free crystals to a homogeneous deformation in H-charged crystals due to the enhanced dislocations self-multiplication.