A unified explanation for variation of the grain growth exponent based on grain boundary migration kinetics

Based on molecular dynamics simulation on grain boundary migration, the large grain growth exponent extensively observed in high-purity nanocrystalline materials is proved to be ascribed to specific boundary migration kinetics determined. It is also found that temperature, topology of polycrystal and grain boundary type all affect the migration kinetics, which therefore causes the exponent to vary. The findings obtained in this work are capable of rationalizing various grain growth phenomena. In addition, triple junction drag against boundary migration has been evaluated and discussed.