KINETICS OF GROWTH AND COARSENING OF FACETED HEXAGONAL PRECIPITATES IN AN FCC MATRIX .2. ANALYSIS

Analyses are developed for three processes observed in the preceding paper. These are: (i) the formation of thickening ledges at the intersection of plate-like precipitates, (ii) the thickening kinetics of plate-like precipitates when much of the solute supersaturation has been released by the formation of metastable GP zones and (iii) the kinetics of the interfacial energy driven shape change of plate-like precipitates relaxing back toward their equilibrium shape. Conventional models for the first process are shown to be incapable of accounting for the observed effects. In the second process the analysis developed here was found to be appropriate. In the third process a numerical model developed was developed, and this demonstrated that the observed shape change was occurring at rates that were much slower than expected for volume diffusion control.