Hydrogen enhanced cracking via dynamic formation of grain boundary inside aluminium crystal

DG Xie and L Wan and ZW Shan, CORROSION SCIENCE, 183, 109307 (2021).

DOI: 10.1016/j.corsci.2021.109307

By in situ bending tests inside an environmental transmission electron microscope, we found that from the precrack tip of single crystalline aluminium cantilevers, dislocations are emitted and self-organized to build a low angle grain boundary (LAGB), along which the crack propagates more easily in hydrogen atmosphere than in vacuum. Atomistic modelling suggests that the LAGB formed can strongly trap hydrogen atoms, and its cohesive strength can be substantially reduced. These results imply that the hydrogen-induced transgranular crack in a polycrystalline metal can proceed by repeating a process of dynamically forming a hydrogenated LAGB and its subsequent separation in grain.

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