Grain boundary wetting in polycrystals: wettability of structure elements and liquid phase connectivity (part I)

A model is proposed describing the wetting of internal structure elements of polycrystals (grain boundaries, triple lines and quaternary nodes). The assumption is made that the only driving force for wetting is the minimization of interfacial solid–solid and solid–liquid energies. The former is assumed to be more scattered than the latter, as a function of the grain boundary misorientation. The well known Gibbs–Smith condition for grain boundary wetting is extended to grain edges and vertices, by introducing a parameter defined as the ‘characteristic free energy’ of these elements. Also suggested is a simple method allowing one to find relative amounts of wetted and non-wetted faces, edges and vertices. The percolation theory is employed to evaluate the critical solid–liquid to solid–solid energy ratio at which liquid phase inclusions become interconnected in a polycrystal of any size.