Grain boundary segregation and fracture

This paper describes a combined thermodynamic and micro-mechanical model for the propagation of a grain boundary crack through a solid in which stress concentrations ahead of the crack and plastic deformation around the crack tip are considered. It is shown that critical factors are impurity segregation concentration, grain boundary structure, reflected in the Sigma value of the boundary, and temperature. Comparisons of the model predictions are made with other models of grain boundary binding by Sutton. Additionally, the model predictions are compared with several experimental observations of grain boundary fracture strength. It is shown that ductile to brittle transition temperature data for steels are a valuable source of experimental grain boundary fracture information for this important range of commercial materials.