The characteristic features of diffusion-induced grain boundary migration in this system were studied by using the [110] asymmetrical tilt boundaries of Cu bicrystals, which had been annealed at 693K, and a zincification technique. Experiments were carried out on boundaries with inclination angles of 0, 20, 35, 55, 65 or 90º and a constant misorientation angle of 39º (Σ9). During annealing, the grain boundary tended to migrate towards the crystal grain of higher coherency strain energy. Upon taking the elastic anisotropy of each crystal grain into account, the difference between the probabilities of grain-boundary migration towards both grains could be explained in terms of the Hillert coherency strain model. The migration rate of the moving boundary was almost constant, regardless of annealing times of between 72 and 384h. The migration rate decreased monotonically with increasing inclination angle. This implied that the boundary diffusion coefficient of Zn in Cu was a monotonically decreasing function of the inclination angle. The steady-state kinetics were analyzed theoretically by using the Kajihara-Gust energy-balance model. This analysis indicated that the effective driving force for grain-boundary migration was only one-thirtieth of the chemical driving force, but it was still 3 times greater than the minimum value which corresponded to the coherency strain energy during diffusion-induced grain boundary migration (under the present conditions). The mobility of the moving boundary was estimated to be equal to 3.77 x 10-17m4/Js.

Characteristic Features of Diffusion-Induced Grain-Boundary Migration for Σ9 [110] Asymmetric Tilt Boundaries in the Cu(Zn) System. N.Goukon, T.Ikeda, M.Kajihara: Acta Materialia, 2000, 48[7], 1551-62