| Abstract Scope |
A review of recent advances in the current understanding of grain boundary diffusion in metallic materials is provided. Geometrically, a grain boundary is characterized by five degrees of freedom and grain boundary diffusion is influenced by all of them. Being complicated already, the defects of interfaces, aka disconnections and grain boundary dislocations, influence the atomic transport significantly, already for pure metals. In alloys, the situations become even more complex due to an interplay of segregation, precipitation, and interface structures, evolving to a microcosm of parameters required for an adequate description of the diffusion phenomena. Current understanding corroborated by radiotracer diffusion measurements and detailed microscopic examinations is presented mainly for Ni-based systems, ranging from pure Ni bicrystals to Ni-containing high-entropy alloys. |