Phase-field modeling of grain growth in presence of segregations on grain boundaries in ceramic matrix microcomposites
The grain boundary diffusion and segregations on grain boundaries can influence the grain growth kinetics, the grain size distribution, and therefore the mechanical properties of the ceramic matrix composites. The present work proposes a phase-field modeling approach to simulate the grain growth in polycrystalline alumina fibers embedded in alumina matrix at temperatures above 1000°C in presence of the grain boundary diffusion of matrix and fiber components from the outer to the inner region and visa verse. The multi-phase-field model is extended by the incorporation of the grain boundary diffusion, grain boundary segregation model, and the dependence of the interface mobility on the segregation concentration. The kinetic parameters of the model were estimated by the comparison to the experimental measurements. The simulation and experimental results of the grain growth with the diffusion of MgO and SiO2 in Nextel 610 fibers show the significant effect of the grain boundary diffusion on the grain size distribution.