Analysis of Grain Boundary Pinning by Secondary Phase Particles Through Phase Field Modeling

A critical microstructural characteristic of polycrystalline materials that determines their distinctive mechanical and physical properties is the grain size distribution. Thermal and mechanical processing methods are specifically selected to manipulate the grain structure, and presence of second-phase particles are can modify grain morphology. Despite a vast amount of experimental data available for a wide range of alloy systems, predictive modeling of grain boundary mobility and pinning effects of secondary-phase particles remains a challenge. Here we present results of phase-field simulations investigating the pinning effect exerted by secondary-phase particles on grain boundary migration. The phase field model is defined in such a way so that computational grain growth rate can mimic experimental results from literature as well as our lab-based testing. The current study shows that it is possible to predict and quantify the impact of particles on the migration of the grain boundaries: specifically the rate of motion of grain boundaries decreases in regions adjacent to the particle. Thus, the pinning effect is prominent within a specific “interaction zone” around the particle location. The presence of finer grain microstructures surrounding the second-phase particles contrasting with coarser grain microstructure away from the pinning effect exerted by the particles, results in abnormal grain growth during the microstructural evolution.