Monte Carlo simulation of hydrogen diffusivity in aluminum with anisotropic grain boundaries

The hydrogen diffusivity in polycrystalline aluminum is simulated by the Mo nte Carlo method based on the random walk theory. We have previously perfor med a simulation of hydrogen diffusivity in aluminum with isotropic grain b oundaries, known as the grain boundary cross (GBC) effect. In this study, a similar diffusivity simulation of a sample with anisotropic grain boundari es is pel formed. The anisotropy of grains corresponds well with the column ar grains in the real specimens for which the diffusivity peak was measured . For samples with anisotropic grain-shapes, the hydrogen diffusivity is en hanced along the longer side of grain boundaries for larger grains, and is increasingly suppressed by trapping at grain boundary junctions for smaller grains. This results in a complicated or disordered peak at some intermedi ate grain sizes. This is termed the grain boundary anisotropic (GBA) effect . An examination of these simulation results supports and confirms the anis otropic qualities of the GBC effect previously determined experimentally by us.