Abstract A theory is presented which describes the dynamics of thermal groove formation at a moving grain boundary. The treatment is based on the Gibbs-Thompson formula relating curvature to chemical potential, and assumes surface diffusion to be the mechanism of groove development. It is proved that a boundary will become stuck at the surface if the magnitude of the angle it makes with the surface normal is less than a critical value θc. This result is combined with certain consequences of the soap film model of grain boundaries to deduce an explanation of the specimen thickness effect of grain growth. Additional experimental evidence is presented and interpreted showing that thermal grooves do retard boundaries that terminate on a surface causing their migration to be spasmodic. Finally, a discussion is given of the hypothesis that a certain type of exaggerated grain growth is caused by inequalities in gas—metal inter facial free energies.
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