A comparison of theory and simulation with microgravity experiments on phase coarsening

Abstract

A quantitative understanding of microstructure evolution during phase coarsening is crucial to the optimization of processing, final structure, and properties of materials at high homologous temperatures. For example, microgravity experiments on phase coarsening in Pb-Sn solid-liquid mixtures allowed the kinetics of phase coarsening to be followed more closely and more accurately by eliminating sedimentation and convective melt flow. In this study we developed phase-field simulations to study microstructure evolution during solid-liquid phase coarsening. Physical properties for Pb-Sn solid-liquid mixtures were calculated using CALPHAD. Simulated microstructure features during phase coarsening are compared quantitatively with the microstructure evolution and kinetics extracted and archived from microgravity experiments. In particular, experimental particle size distribution and coarsening rate constant are predicted from theory, and deduced from microgravity experiments, then calculated from phase-field simulations. The new results from phase field simulations agree with the results from archived microgravity experiments for a lower volume fraction alloy, and still acceptably for Pb-Sn alloys with higher volume fraction.