Atomistic Study of the Interaction Nature of H-Dislocation and the Validity of Elasticity in Bcc Iron

Abstract

One way to assess the validity of elasticity is with the method of atomic simulations. Molecular statics (MS) simulations are performed to study the interactions between H and edge dislocations in bcc iron using embedded-atom-method potential for a Fe-H system. The nature of H-dislocation interactions can be investigated and the validity of elasticity can be examined. We show that the sites with strong binding energy are found at the dislocation core, as well as in the slip plane, suggesting high H concentrations can form along the slip plane. It is found that the interstitial H not only interacts with hydrostatic stress, but also with the shear stresses generated by the dislocation, especially on the slip plane. When the dislocation stresses are represented using anisotropic elasticity, the validity of elasticity is at H-dislocation distance larger than ~19 Å, i.e., the same as the isotropic predictions. When H lies closer to the dislocation, good agreement with simulations is obtained if considering all strains induced by H at the octahedral sites and using anisotropic elasticity.