The grain boundary diffusion of Ag was measured in Cu-0.2at%Ag at 473 to 970K. Direct measurements of the Ag grain boundary diffusivity, Dgballoy, under Harrison C regime conditions revealed that Dgballoy was almost identical to Dgbpure for Ag diffusion in high-purity Cu. The penetration profiles which were determined in the Harrison B regime exhibited a complex multi-stage shape. This diffusion behavior could be rationalized by assuming that, as well as grain boundaries which were largely covered by segregated Ag atoms, a fraction of the grain boundaries remained almost free from Ag atoms. This was confirmed by measurements of Ag grain-boundary diffusion in near-Σ5 Cu bicrystals, which permitted detailed analysis of the non-linear segregation of Ag in Cu grain boundaries. The total number of so-called pure grain boundaries decreased sharply with decreasing temperature.

Grain Boundary Diffusion and Linear and Non-Linear Segregation of Ag in Cu. S.Divinski, M.Lohmann, C.Herzig: Interface Science, 2003, 11[1], 21-31