A mathematical model for the solute drag effect on recrystallization

The model for solute drag effect in phase transformations has been applied to recrystallization, i.e. moving grain boundaries. In this model, the total driving force is dissipated by the interfacial energy, the finite interfacial mobility, the solute drag in boundaries and the diffusion in matrix ahead of the interface, of which all are taken into account consistently. The effect of the Gibbs energy of segregation and the diffusivity of impurity atoms in boundaries was investigated. The result shows that the Gibbs energy of segregation mainly affects the critical composition at which the drastic change in the boundary velocity appears and the diffusivity of impurity atoms in boundaries mainly affects the velocity reduced by the solute drag effect. In other words, the Gibbs energy of segregation and the diffusivity of impurity atoms in boundaries can be evaluated from experimental data by means of the present model. This model was applied to the Al-Mg system and the Gibbs energy of segregation and the diffusivity of Mg in boundaries were evaluated from the experimental data.