Movement of pores in solids

Abstract

Our discussion has covered a great deal of ground and that in rather cursory fashion, but it is hoped that it will serve as an introduction to the subject which will aid the interested reader in the assimilation and assessment of the very large number of papers available in the literature. The basics of the behavior of pores, both voids and bubbles, in solids, with and without driving forces, appear to be well-established. Quantitative agreement between theory and experiment has been obtained in several instances, all involving a dominant driving force, either curvature or thermal gradient. On the other hand, when no driving forces exist, the restraining effects of structural defects must be carefully considered in any “random-walk” analysis. Also, the effects of faceting of pores due to anisotropy of surface tension become very important. Further effects of possible significance include strain field interactions between pores or between pores and surfaces. In short, when no driving force is applied, many normally small effects take on great importance and are extremely elusive of quantitative analysis. On the other hand, the presence of a strong driving force may well “swamp out” these effects and thus provide results in agreement with predictions of an idealized theory.