Grain boundary impurity diffusion of Au in diffusion bonded ∑ 3(011) Cu bicrystals has been studied by the radiotracer serial-sectioning technique using the ~195Au isotope with high specific activity. The dependence of the grain boundary diffusion parameter sδD_b on the inclination angle Φ of the grain boundary plane with respect to the close-packed (111) plane of the coherent twin boundary has been deter- mined for the temperatures of 673 and 773 K (here s, δ and D_b are the segregation factor, the grain bound- ary width and the grain boundary diffusion coefficient, respectively). At both temperatures sδD_b exhibits a minimum at Φ = 70.5°and a maximum at Φ= 82.0°It is shown that there is no direct correlation between the energy and diffusivity of the grain boundaries in this system and that the periodicity in the grain boundary plane has a significant influence on the grain boundary diffusivity.
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