Diffusion and redistribution of hydrogen atoms in the vicinity of localized deformation zones

The presence of hydrogen atoms in the lattice of polycrystalline metals can lead to hydrogen embrittlement. The diffusion of hydrogen atoms and formation of hydrides depend on several parameters such as the microstructure of the metal alloy, the presence of stress risers, and the applied loading condition. In this study, a non-local crystal plasticity finite element model is coupled with hydrogen diffusion equations to study the effects of such parameters on the stress-assisted diffusion of hydrogen atoms in zirconium polycrystals. The concentrations of hydrogen atoms in the lattice and dislocation trap sites under different scenarios are studied to deconvolute the effects of texture, microstructure, and applied strain on hydrogen diffusion. It is shown that the concentration of hydrogen in the lattice peaks in the vicinity of grain boundaries and most importantly, at the triple-junction points. It is further shown that in localized deformation zones, such as twin or notch tips where dislocations concentrate, the effects of trapped hydrogen content can be significant.

Automated summary

The presence of hydrogen in the lattice of polycrystalline metals can result in hydrogen embrittlement, and its diffusion and formation depend on various factors. The study combines a non-local crystal plasticity finite element model with hydrogen diffusion equations to investigate the effects of these factors on stress-assisted hydrogen diffusion in zirconium polycrystals. The concentration of hydrogen is found to peak at grain boundaries and triple-junction points, and its effect on trapped hydrogen content can be significant in localized deformation zones.