The effect of solution thermodynamics upon the mobility of grain boundaries in the presence of diffusing impurities was analyzed within the framework of impurity drag theory for an ideal solution. The new derivation was performed within the framework of the regular solution model. The effects of non-ideality were greatest when the impurities were attracted to the grain boundary and the deviation from ideality was positive. Positive deviations from ideality led to an enhanced impurity drag on the boundary, and negative deviations led to a higher boundary mobility. When the impurities were attracted to the boundary, positive or negative deviations from ideality produced larger or smaller activation enthalpies for boundary migration, respectively, relative to an ideal solution. For high impurity concentrations, the activation enthalpy became independent of the impurity concentration. Decreasing impurity concentrations in ideal solutions, and regular solutions with a negative deviation from ideality, led to a decrease in the activation enthalpy for migration.

A Regular Solution Model for Impurity Drag on a Migrating Grain Boundary. M.I.Mendelev, D.J.Srolovitz: Acta Materialia, 2001 49[4], 589-97