STUDY OF INTERGRANULAR CAVITY GROWTH IN AG + 0.1-PERCENT-MGO AT ELEVATED-TEMPERATURES

In a previous study by Goods and Nix, it was shown that implanted grain boundary cavities in Ag grow by a process controlled by surface self diffusion. Accordingly, any changes in the strength of the adjoining grains would not be expected to affect the rate of cavity growth. In the present work, grain boundary cavities were implanted in Ag + 0.1% MgO and their growth kinetics were studied under creep conditions. We show that the fine dispersion of MgO particles present in this material greatly strengthens the matrix and reduces the overall creep rate, as expected, but leaves the rate of cavity growth unchanged. It is concluded that the contributions to cavity growth by plastic flow are negligible and that the mechanisms of cavity growth in Ag and Ag + 0.1% MgO are the same. A model developed originally by Chuang and Rice accurately describes the kinetics of cavity growth in these materials. © 1979.