Mechanisms for diffusion of point defect-solute complexes in alloys

Some non-equilibrium kinetic processes, such as irradiation-induced segregation and precipitation, and thermal non-equilibrium segregation, require the presence of point defect-solute complexes as part of the underlying mechanism. The kinetics of these processes need knowledge of the diffusivity for the complexes. In view of the limited data available, we have discussed mechanisms for migration of the complexes in both fee and bcc crystals. In accordance with the mechanisms, it is possible to predict the activation energy for migration of the complexes. Examples of the use of predicted data to satisfactorily evaluate phosphorus grain boundary segregation in low-alloy steels are described.