ABSTRACT
A substantial part of research on polycrystalline materials is concerned with the accurate determination, assessment, and theoretical prediction of orientation relationships between adjacent crystals. There are obvious practical applications, such as in the study of anisotropy and texture, or in defining the role of interfaces in controlling the mechanical properties. The existence of a reproducible orientation relation between the parent and product phases might determine the ultimate morphology of any precipitates, by allowing the development of low interfacial-energy facets. It is possible that vital clues about nucleation in the solid state might emerge from a detailed examination of orientation relationships, even though these can usually only be measured when the crystals concerned are well into the growth stage. The reduction in interfacial energy between the precipitate and matrix when a specific relationship is adopted. This facilitates nucleation because the activation energy for nucleation scales with the cube of the interfacial energy per unit area.
