Migration of vacancies near twin boundaries in body-centred-cubic metals

Computer simulation methods have been used to demonstrate that the migration energy of a single vacancy in α-iron can be changed dramatically by the presence of a neighbouring {112} twin boundary. In particular, vacancy migration parallel to a twin boundary is enhanced, which suggests that the presence of twins may have important consequences for diffusional creep. The results can be interpreted satisfactorily in terms of the atomic structure of the twin boundary and are therefore considered to be typical of all body-centred-cubic metals. Possible effects of other boundaries on vacancy migration are also discussed briefly.