Kinetic enrichment of hydrogen at interfaces and voids by dislocation sweep-in of hydrogen

Abstract

A rigorous treatment is presented to answer the question of whether the dislocation sweep-in of hydrogen can result in enrichment of hydrogen at voids and boundaries. It is concluded that significant enrichment can occur in both low and high hydrogen diffusivity situations whether the enrichment is contributed by a dislocation annihilation process or by stripping of hydrogen atoms from dislocations by the internal traps. The model presented is based on enrichment controlled by long-range diffusion. It calculates the diffusion leakage current for the case where unsaturated trap interfaces simultaneously fill and leak hydrogen atoms into the matrix by diffusion, and compares this amount with the arrival current of hydrogen to the traps by dislocation sweep-in. The relative magnitudes of the two currents are found to depend on appropriate, calculable time constant values. These values are evaluated for physical situations of interest.