Grain boundary segregation. The current situation and future requirements

The point of departure of this review is that the phenomenon of grain boundary segregation in polycristalline materials can be treated by the classical procedures and notions of surface chemistry. The main established experimental and theoretical features of reversible grain boundary segregation are assessed, together with a critical selection of the most important or most promising techniques for its study. This includes a discussion of the origin and nature of grain boundary activity, the various adsorption isotherms that are relevant, the form and distribution of grain boundary segregants, solute interactions at grain boundaries and the anisotropy of segregation. The deficiencies in the current understanding of the phenomenon are noted