Local mobility variations along recrystallization boundaries

Understanding recrystallization boundary migration mechanisms is crucial for materials design. However, the lack of comprehensive mobility data for high-angle grain boundaries in typical polycrystalline samples has impeded gaining insights into the factors that govern boundary migration. Here, we propose an Iterative Mobility Matching (IMM) methodology to determine local mobility values and their spatial variations along recrystallization boundaries in partially recrystallized samples. This method optimizes mobility inputs in a phase field model by matching simulated microstructures with time-series recrystallization experiments. We first validate this method using synthetic data before applying it to real experimental data. For the first time, we reveal a three-order-magnitude variation in local mobility along individual recrystallization boundaries. The results show that local mobility depends strongly on boundary misorientation, and its variation significantly influences boundary dynamics, shedding light on the interplay of factors that impact the observed boundary migration behavior. The IMM methodology offers a new framework for interpreting experimental recrystallization behavior and can be broadly applied to other materials using in situ experiments.