The grain-boundary diffusion of Cu was measured in Cu bicrystals, with symmetrical near-Σ5, 36.9º (310)[001] coincidence-site lattice tilt grain boundaries, by using radiotracer and serial sectioning techniques. The orientations of the bicrystals were precisely determined by using the Kossel technique, and all 3 macroscopic parameters which described the orientations were evaluated. The tilt angles ranged from 33.21 to 39.26º. The grain-boundary diffusion of 64Cu was measured as a function of the tilt angle and temperature (table 42). At temperatures ranging from 661 to 1030K, the orientation-dependence of the radiotracer exhibited a characteristic cusp. This was slightly below the ideal Σ = 5 coincidence-site lattice grain boundary. The activation enthalpy and frequency factor, as determined from lower-temperature data, exhibited a maximum slightly below the ideal Σ = 5 coincidence-site lattice grain boundary. A negative deviation from a straight Arrhenius plot was observed with increasing temperature. This reflected a change in the grain boundary structure at temperatures above 800K.

E.Budke, T.Surholt, S.I.Prokofjev, L.S.Shvindlerman, C.Herzig: Acta Materialia, 1999, 47[2], 385-95