Effect of Different Initial Structures on the Simulation of Microstructure Evolution During Normal Grain Growth via Phase-Field Modeling

The effect of different initial structures on the simulation of microstructure evolution during normal grain growth was comparatively studied by using a two-dimensional phase-field model. Three methods, standard Voronoi construction, weighted Voronoi construction, and hand drawing, were used to generate the initial structures. For the hand-drawn initial structure, different boundary conditions, including periodic and gradient boundary conditions, were also applied. The phase-field simulation of normal grain growth in the succinonitrile-coumarin152 system was chosen as the benchmark, and compared with the experimental microstructure evolution. The phase-field simulated results generally conformed to Hillert's theory, Von Neumann-Mullins law, and the experimental results. Different initial structures with similar initial grain size distribution showed similar grain size evolution. The simulation results for the experimental initial structure constructed by hand drawing showed best agreement with the experimental results during the early stage of grain growth process. With the increased time, the accuracy of simulation appeared strongly dependent on the grain numbers, and thus the gradient boundary condition is more suitable for long-time grain growth simulation than the periodic boundary condition. Overall, the combination of phase-field simulation and experimental initial microstructures allows the study of the grain growth in arbitrary polycrystalline materials, as demonstrated here for comprehensive study of austenite grain growth in two commercial high-strength steels.