A model for ideal cleavage fracture of grain boundaries in b.c.c. metals

Abstract

The random grain boundary model is used to determine the work of adhesion of symmetrical high-angle twist grain boundaries (GBs) in b.c.c. metals. In this idealized theoretical model of a high-angle GB, the interactions of atoms across the interface are assumed to be entirely random. Because fully relaxed free surfaces are included naturally, the model is well suited for the determination of GB cleavage-fracture energies. From an investigation of the role of the GB plane, in particular of the interplanar spacing parallel to the GB, it is concluded that, as in the case of free surfaces, ‘special’ and ‘vicinal’ interfaces have fundamentally different physical properties.