The strength of the isotope effect for the diffusion of zinc in copper is 0.41 at 894.5 and 946.4°C. The most probable value of the correlation factor for the diffusion of zinc in copper is 0.55. The strength of the isotope effect for the diffusion of zinc in disordered CuZn at 560.3°C is 0.245; it is 0.201 for diffusion in ordered CuZn at 410.6°C ($S=0.7\mathrm{}$). The near equality of these numbers indicates that next-nearest-neighbor jumps are not probable, that the details of the diffusion mechanism are the same in the ordered and disordered phases, and that at this degree of long-range order, the Elcock-McCombie mechanism is not dominant.

• Received 18 August 1966

DOI:https://doi.org/10.1103/PhysRev.154.558