Chemical driving force for rafting in superalloys

Abstract

The author provides a brief overview of the chemical driving forces for rafting in superalloys. Until recently, all theories of the driving force for rafting have considered the compositions of the two phases to be fixed, although accepting that the rate of rafting might be controlled by diffusion. The analysis in the elastic regime (e.g. 1,2) rests on Eshelby’s recognition that the thermodynamic pressure on an interface has two components: (i) the difference in elastic energy densities across the interface, and (ii) the work done by the normal traction across the interface when the interface moves.