Grain boundary diffusion: recent progress and future research

Grain boundary (GB) diffusion often controls the evolution of structure and properties of engineering materials at elevated temperatures. A knowledge of diffusion characteristics of GBs and deep fundamental understanding of this phenomenon are critical to many materials applications. In this paper we give an overview of boundary diffusion theory with emphasis on the interpretation of concentration profiles measured in diffusion experiments. We consider the most important situations encountered in boundary diffusion experiments, such as diffusion in the B and C regimes and diffusion in the presence of segregation. We also discuss the recent progress in the atomistic interpretation of GB diffusion. We conclude with an outlook for future research in this area.