Trapping of Hydrogen by Structural Defects in α-Iron

Abstract

The anomalous diffusivity of hydrogen in cold-worked iron at low temperatures is due to the attractive interactions between dissolved hydrogen and structural imperfections produced by the deformation. Since hydrogen atoms occupying interstitial sites expand the host lattice, crystal defects such as vacancies, dislocations and interfaces trap hydrogen and affect thus the mobility of hydrogen atoms in the iron lattice. Effusion measurements, therefore, under conditions in which hydrogen diffusion is the rate determining process, yield information concerning the trapping reaction and the binding energy for hydrogen trapped by lattice defects.