The results of molecular dynamics and transition state studies upon the influence of grain boundaries on hydrogen transport were reported. An exhaustive mapping of possible minimum activation energy migration trajectories for hydrogen as the trace impurity revealed a strongly modified activation energy distribution in the neighborhood of grain boundaries, together with an altered connectivity matrix. The results indicated that grain boundaries in polycrystalline tungsten could provide an important transport channel; especially for neutron-damaged tungsten.

Molecular Dynamics Study of Grain Boundary Diffusion of Hydrogen in Tungsten. Von Toussaint, U., Gori, S., Manhard, A., Höschen, T., Höschen, C.: Physica Scripta T, 2011, 145, 014036