Cavity nucleation at high temperatures involving pile-ups of grain boundary dislocations—effect of solutes and impurities

Abstract

This paper extends the grain boundary dislocation pile-up model [ Acta metall. 35, 1663 (1987)] to address the problem of solute/impurity enhanced cavitation at high temperature. It is shown that solute/impurity enhanced cavitation is a complex phenomenon. This is because solutes/impurities can alter a host of material parameters such as interfacial and surface energies, boundary diffusivity and creep resistance of the materials. Changes in interfacial and surface energies can alter the thermodynamics of cavity formation, while changes in boundary diffusivity and creep resistance can significantly influence the steady state pile-up strength at the interface. These changes would collectively produce a profound effect on the cavitation behavior of the material. The findings show that solutes/impurities which are strongly surface active, retard boundary diffusivity and decrease the creep resistance of the material are most deleterious; they can reduce the threshold stress for cavitation failure of the material by about an order of magnitude.