Grain boundary motion in 5N8- and 5N-purity Cu was investigated by using the results of radiotracer grain-boundary diffusion measurements and tracers which exhibited fundamental differences in their solute/matrix-atom interactions. Results on the grain boundary solute diffusion of Ag (with a miscibility gap in the Ag-Cu phase diagram) and Au (which formed intermetallic compounds with Cu), and on Cu self-diffusion, were analyzed. The initial parts of the Ag and Cu penetration profiles were substantially curved. The profile curvature was explained in terms of the effect of grain boundary motion during 110mAg and 64Cu grain boundary penetration. The activation enthalpies of grain-boundary motion in the 2 independent measurements were very close (95 and 103kJ/mol, respectively). These values were still somewhat larger than the activation enthalpy (72kJ/mol) for Cu grain-boundary self-diffusion in material of the same high purity. Although tracer diffusion measurements of Au grain boundary diffusion in Cu yielded only limited information on grain boundary motion, the absolute values of grain boundary velocity were consistent with those deduced from Ag and Cu grain-boundary diffusion data.

Grain Boundary Motion during Ag and Cu Grain Boundary Diffusion in Cu Polycrystals. S.V.Divinski, M.Lohmann, T.Surholt, C.Herzig: Interface Science, 2001, 9[3-4], 357-63