Two models were used to interpret tracer diffusion and isotope-effect data for β-CuZn. The first model was a 4-frequency one in which the atom-vacancy exchange frequencies were assumed to be independent of their environment; apart from the sub-lattice. The second was the Ising nearest-neighbor atomic interaction model. In the former model, it was found that the correlation factors contributed about one half and one third of the activation energies for the tracer diffusion of Zn and Cu, respectively. The correlation factors for the more realistic Ising model contributed about one quarter and one eighth of the activation energies for the tracer diffusion of Zn and Cu, respectively. The correlation factors in β-CuZn, as deduced from the isotope effect, had to be analyzed by using the impurity form of the correlation factors. This was possible by using the analytical approach for both models, and a computer simulation method. The best estimate of the correlation factor for Zn diffusion at 683K was 0.4, while the best estimate for the correlation factor for Cu diffusion was 0.59.

An Interpretation of Tracer Diffusion in β-CuZn I.V.Belova, G.E.Murch: Acta Materialia, 1998, 46[3], 849-55