Grain-boundary diffusion of hydrogen atoms in the α-iron

Abstract

Grain boundary diffusion of hydrogen atoms in the α-iron is analysed based on the theoretical modelling. By means of molecular-dynamics simulation of hydrogen-atoms' migration in selected special grain boundaries with different misorientation angles as well as in the bulk, it is demonstrated that the activation enthalpy of hydrogen migration in the grain boundary is higher than that in the bulk. Based on this result, a conclusion is made that grain boundaries in the iron are traps for hydrogen atoms and retard their migration. As supposed, an increase in the hydrogen grain-boundary diffusion, as observed in some experiments, is related to the hydrogen-caused intergranular cracking.