KINETICS OF PHASE COARSENING IN DENSE SYSTEMS

Diffusion-limited coarsening is formulated as a statistical descriptio n of the evolving particle size distribution. Diffusional interactions among dispersed particles are accounted for using a statistical field cell associated with each particle size class. The field cells correl ate particle volumes with an averaged growth rate and the correspondin g volume of the matrix phase associated with a particle's transport fi eld. The particle and matrix volumes obey a linear affine transformati on, derived here from self-similar dynamics. The coarsening kinetics a re determined by adding two global constraints on the distributional r epresentation of the microstructure, which specify the volume fraction and critical (zero-growth) particle size in terms of explicit spatial and ensemble averages. Comparison of the theoretically predicted coar sening rates with those obtained from liquid-phase sintering experimen ts in binary alloys show agreement over a wide range of phase fraction s.