Abstract
The isotope effect for diffusion of cobalt in single-crystal α-titanium has been measured over the temperature range from 615 to 824°C. The measured isotope effect coefficients, E, parallel and perpendicular to the c-axis are 0.08 and 0.31, respectively. The expression for the coefficients E is derived by assuming the interstitial mechanism in which cobalt atoms are allowed to occupy both the octahedral and tetrahedral interstices. It is concluded that the small E values should be ascribed, not to the small value of correlation factors, but to the small value of the many-body factor, ΔK.