Diffusion in gamma uranium : final report--metallurgy program 4.1.27 /

A "Kirkendall-effect" experiment with a very slight concentration gradient showed that diffusion takes place by a defect mechanism. Pre-annealing a sample near the melting point, cooling to the diffusion temperature without going into the beta phase, depositing the isotope, and diffusing gave the same D as a conventional experiment, indicating that excess defects were not introduced by the beta to gamma transformation. Small additions of cobalt were shown to have a profound effect on self-diffusion in gamma uranium. These results can be explained only on the basis of the vacancy or interstitialcy mechanisms.The diffusion of chromium, manganese, iron, molybdenum, nickel, copper and neodymium tracers in gamma uranium has been measured by use of the thin-layer-sectioning technique. The plots of log D (the logarithm of the diffusion coefficient) vs 1/T (the reciprocal of the absolute temperature) are curved at low temperatures. The data do not agree quantitatively with any of the present theories of diffusion."Portions of the material in this report have appeared in the following Metallurgy Division Progress Reports: ANL-6099 (102-105) Dec. 1959; ANL-6330 (197) Dec. 1960; ANL-6516 (286-298) Dec. 1961; ANL-6677 (308-321) Dec. 1962; ANL-6868 (287-289) Dec. 1963; ANL-7000 (163) Dec. 1964.""November 1965."Includes bibliographical references (p. 91-94).A "Kirkendall-effect" experiment with a very slight concentration gradient showed that diffusion takes place by a defect mechanism. Pre-annealing a sample near the melting point, cooling to the diffusion temperature without going into the beta phase, depositing the isotope, and diffusing gave the same D as a conventional experiment, indicating that excess defects were not introduced by the beta to gamma transformation. Small additions of cobalt were shown to have a profound effect on self-diffusion in gamma uranium. These results can be explained only on the basis of the vacancy or interstitialcy mechanisms.The diffusion of chromium, manganese, iron, molybdenum, nickel, copper and neodymium tracers in gamma uranium has been measured by use of the thin-layer-sectioning technique. The plots of log D (the logarithm of the diffusion coefficient) vs 1/T (the reciprocal of the absolute temperature) are curved at low temperatures. The data do not agree quantitatively with any of the present theories of diffusion.Operated by the University of ChicagoMode of access: Internet