The structures of symmetrical tilt grain boundaries with various tilt axes, and their interaction with vacancies and interstitials, were studied by using atomistic computer simulations with embedded-atom potentials. The lowest defect formation energy in a grain boundary was found to be related to the grain-boundary energy. Vacancies and self-interstitials in grain boundaries had comparable formation energies; thus suggesting that both defects were equally important to grain boundary diffusion. The vacancies in grain boundaries could be localized at certain sites, or be delocalized over several sites. Some grain-boundary sites did not support a stable vacancy. Self-interstitial atoms could occupy relatively open interatomic positions, form split dumb-bell configurations or give rise to highly delocalized displacement zones. These structural forms of the point defects were observed for 12 grain boundaries in Cu and 6 grain boundaries in Al. It was suggested that these structural forms were common to all grain boundaries in face-centered cubic metals. They could be explained by the existence of internal stresses, and alternating tension and compression regions, in the grain-boundary core.

Interaction of Point Defects with Grain Boundaries in FCC Metals. A.Suzuki, Y.Mishin: Interface Science, 2003, 11[4], 425-37