DIFFUSION AND VACANCY PROPERTIES OF ALPHA-ZR

An analysis of solute diffusion data in terms of atomic size considerations suggests a normal value for the activation energy for self-diffusion (3. 2 eV). In addition, a value for the activation energy for vacancy migration in alpha -Zr (and alpha -Ti and Hf) has been estimated from elastic coefficient data; the result (1. 6 eV) is also indicative of normal metal behavior. The results are at issue with experimental data: the latter show abnormal curvature of the Arrhenius plot for self-diffusion and an abnormally low vacancy migration temperature. In the case of self-diffusion, a possible resolution of the situation has recently been advanced.