Analysis of pore shrinkage by volume diffusion during final stage sintering

Abstract

The steady‐state flows of gas atoms and vacancies leaving a pore that is either on the surface, or at various positions inside of a spherical grain have been calculated by approximation methods for the conditions that exist during the final stage of sintering. Gas and vacancies were assumed to leave pores by volume diffusion only. It was found that the position of a pore in a grain should have little effect on its shrinkage rate—a result that appears to be in general accord with previous experimental observations on various materials. The rate of shrinkage of pores on grain boundaries in the one material investigated appears to be many times greater than that predicted by the calculations, implying that shrinkage of such pores was not controlled by volume diffusion. Pore‐to‐pore diffusion and removal of porosity by grain‐boundary migration are also discussed.