The inhibiting effect of vacancies upon the very process which generated them was considered from the thermodynamic point of view. Such processes included grain growth and pore dissolution. It was shown that these processes were inhibited by vacancy generation involving so-called intermittent locking. Following a period of uninhibited progress, the process would come to a halt due to a thermodynamic back force which effectively locked it. It could then re-start only when the vacancies which were produced were dissipated by diffusion. This cycle led to an overall reduction in the overall rate of the process in question. Specific predictions were made with regard to grain growth in fine-grained (especially nanocrystalline) materials, and void dissolution kinetics, during sintering. A third example which was considered was vacancy drag on an individual moving grain boundary. The magnitude of the drag was re-assessed by taking account of the Gibbs free energies of the vacancies which were generated.

Thermodynamic Effects on the Kinetics of Vacancy-Generating Processes. V.Estrin, G.Gottstein, L.S.Shvindlerman: Acta Materialia, 1999, 47[13], 3541-9