Three-dimensional phase-field study of grain coarsening and grain shape accommodation in the final stage of liquid-phase sintering

A 3-dimensional phase-field model is implemented to simulate the grain evolution in the final stage of liquid-phase sintering. The model considers a liquid phase and a polycrystalline solid phase. Results for varying ratios of the solid-solid interface energy to solid-liquid interface energy and varying solid volume fractions are presented. A variety of microstructures, from fully connected grain structures with liquid pockets at the grain junctions to individual grains fully wetted by the liquid matrix, is seen. The 3 main mechanisms for particle shape accommodation, namely, contact flattening, Ostwald ripening and particle bonding, are reproduced in the simulations. The solid volume fraction, particle size distribution, contiguity, connectivity, particle-particle contact areas and the number of particle contacts per particle are measured as a function of time. The exponent in the power growth law varies between 2.4, for the fully connected grain structures, and 3, for the completely wetted grains.