Abstract
An expression for the net thermodynamic driving force (free energy change per unit distance of reaction front migration per unit area of reaction front) for the migration of reaction fronts during diffusion-induced grain boundary migration (DIGM), discontinuous precipitation (DP) and liquid film migration in binary alloys is determined from a two-dimensional model which considers individual segments of the migrating reaction front as open systems which can receive solute and solvent atoms from or give them up to the surrounding material. In the case of DIGM and DP the reaction front is treated as a separate grain boundary phase of thickness delta .