Vacancy properties in twin boundaries in hcp metals simulated by many-body interatomic potentials

Abstract

Abstract The formation and migration energies of vacancies in the vicinity of {1121}, {1122}, {1011} and {1012} twin boundaries in hcp metals have been studied by using the many-body potentials developed by Igarashi et al. [Philos. Mag. B63 (1991) 603] for Mg and Zr and by Ackland [Philos. Mag., in press] for Ti. The results are compared with those of previous work based on the pair potential na56. It is found that the formation energy of a vacancy is highly influenced by the presence of the interface and the vacancy-twin binding energy depends on the interface crystallography. The results are qualitatively the same for the four potential models and can be partly explained in terms of the pressure acting on the atomic sites. The vacancy migration energy can also be reduced to a significant extent by the presence of the boundary, although the many-body potentials introduce some restrictions on the easy migration paths in comparison with the pair potential. These results can be interpreted in part from the detailed differences between the potentials, but, nevertheless, some conclusions on the general features of vacancy properties in twin boundaries can be drawn.