Study of grain-boundary diffusion of Au in copper within Σ5 misorientation range in the context of structure of grain boundaries

Au-195 and (CU)-C-64 diffusion along [100] symmetric tilt boundaries in copper is studied in detail within a narrow range of misorientations around Sigma 5(310) coincidence boundary. The grain-boundary (GB) diffusion of Au-195 and (CU)-C-64 is examined at temperatures of 661-1030 K for the former and 919 K for the latter. A narrow Sigma 5-minimum is found on misorientation dependences of the GB-diffusion parameter of (195)AU and (CU)-C-64. It is shown that this behaviour is governed by GB-structure rather than chemical factors. Such a behaviour qualitatively differs from predictions of the structural unit model. At the same time this behaviour agrees with predictions based on the model for GB-structure near coincidence misorientations advanced by Brandon. There is a some indication on structure transition at borders of CS-minimum between GB-structure governed by CS-misorientation and structure of general grain boundaries.