VACANCY DRAG - GENERATION OF VACANCIES BY INTERFACE MIGRATION

'Growth accidents' during the migration process of grain boundaries are proposed to result in a supersaturation of vacancies in the lattice of the crystal growing by boundary migration. This vacancy supersaturation exerts a drag force ('vacancy drag') on the migrating interface. The magnitude and the temperature dependence of this vacancy drag may be comparable to impurity drag effects in alloys and may be the dominant drag effect in pure materials. In general, the existence of a vacancy drag results in non-linear relationships between driving force and boundary mobility. The results of the vacancy drag model seem to agree with the existing experimental evidence. © 1979.