A model of migrating grain-boundary grooves with application to two mobility-measurement methods Original Research Article

Grain-boundary migration controls grain growth and is important in materials processing and synthesis. The mobility of grain boundaries is usually measured by the “quarter-loop” and Sun–Bauer methods. In these methods, a grain boundary migrates and its tip position along a free surface is recorded to infer the mobility. At the tip, a groove develops to reduce the combined surface energy. The groove is small and adjusts quickly. Thus, in both methods, the groove can be treated at each instant as migrating at constant speed. We study this quasi-steady groove formed via surface diffusion, and find that the groove turns the grain boundary (by angle θ) away from being perpendicular to the free surface. We add this tilting effect into both measurement methods by solving the migrating grain-boundary profiles for arbitrary θ. Computed profiles agree well with two Sun–Bauer experiments in which θ=18 and 30°.