Grain boundary diffusion in metals: Recent developments

An overview on recent progress in grain boundary (GB) diffusion study is presented with emphasis on physical phenomena encountered in GB diffusion experiments such as the linear and non-linear segregation effects. Systematic investigation, on pure and alloyed poly- and bicrystals gave conclusive information on the solute segregation behavior and allowed to extract the segregation isotherm from GB diffusion studies. Recent progress in fundamental understanding of diffusion processes in two-scale materials with two types of short circuit diffusion paths is discussed on the basis of GB self-diffusion experiments and Monte-Carlo simulations in powder sintered nanocrystalline material.