Is pipe diffusion in metals vacancy controlled? A molecular dynamics study of an edge dislocation in copper

The mobility of vacancies and interstitials trapped on a dissociated edge dislocation in copper is studied by molecular dynamics. Although fast diffusion is thought to occur exclusively in a pipe surrounding the dislocation core, in the present study a quasi-two-dimensional diffusion is observed for defects not only in the cores but also in the stacking fault ribbon. Contrary to current assumptions, the activation energy for diffusion is found to be identical for both defects, which may therefore comparably contribute to mass transport along the dislocations.