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Transformation Kinetics of Plutonium. Part 2. A Study of the Gamma to Beta to Alpha and Alpha to Beta to Gamma Transformations

Description: The kinetics of the gamma deg C was con- beta deg C was con- alpha , beta deg C was con- gamma , and alpha deg C was con- beta deg C was con- gamma transformations were determined with a fiuid displacement technique. The rates of formation of the alpha and beta phases from the gamma phase were determined after gamma heat treating and allowing a sample to traasform isothermally in the alpha and beta ramges. Isothermal reaction curves were obtained from 160 C to -78C. The time-temperature-transformation curve of the gamma deg C was con- beta deg C was con- alpha transformation was plotted. The effect of the gamma heat treating time and temperature on the rate of transformation was examined. Isothermal reaction curves and time-temperature- transformation curves of the beta deg C was con- gamma , and alpha deg C was con- beta deg C was con- gamma transformations were plotted. Photomicrographs of specimens having transformed from the gamma range at different rates of transformation are presented. (auth)
Date: July 18, 1958
Creator: Nelson, R. D.
Partner: UNT Libraries Government Documents Department

Density of metallic polonium

Description: Determinations of the density and coefficient of thermal expansions of postum (Polonium 210) were attempted on 20 curies of polonium as obtained from production foils.
Date: May 18, 1948
Creator: Brody, B.
Partner: UNT Libraries Government Documents Department


Description: ABS>A review of laboratory diffusion studies on uranium and its compounds and alloys is presented. Included are results and analysis of studies on diffusion in single-phase and in multiphase U alloys, diffusion of gases in U, and diffusion in UO/sub 2/. (J.R.D.)
Date: May 1, 1961
Creator: Rothman, S.J.
Partner: UNT Libraries Government Documents Department

THE ADIABATIC ELASTIC MODULI OF SINGLE-CRYSTAL ALPHA URANIUM AT 25 C. Work completed: January 1958. Partial Report-Metallurgy Program 4.1.16

Description: The 9 single-crystal elastic moduli pertaining to principal crystallographic axes of alpha U at 25 deg C were determined from measurements of high-frequency wave velocities for 21 modes in seven single-crystal specimens, using the phase-comparison method of McSkimin. From the results the elastic compliances, compressibilities, and Poisson"s ratios were computed for the principal axes. Th variations with crystal direction of the stiffness moduli, Young's moduli, and rigidity moduli were plotted. The nature of the anisotropy for the different moduli indicated that the nearest neighbor interatomic bonds are considerably stiffer than the next nearest bonds, which are only slightly larger in interatomic distance. (auth)
Date: June 1, 1960
Creator: Fisher, E. S.
Partner: UNT Libraries Government Documents Department


Description: The analysis of a reactor model that is thermally nonlinear is presented. The significant sources of feadback in the closed-loop model ane dilatational changes of the fuel due to axial expansion caused by temperature and metallurgical phase changes. Ths dynamics of this phenomenon has been represented on the Pace electronic analog com puter. The model was subjected to unusually large inputs of sinusoidal power and did not show any drastic tendencies toward being unstable. (auth)
Date: January 1, 1961
Creator: Bryant, L.T.; Carter, J.C. & Janicke, M.J.
Partner: UNT Libraries Government Documents Department


Description: The high temperature enthalpies of five rare earths were measured from 0 to 1100 deg C using a Bunsen ice calorimeter. The enthalpy of yttrium metal was studied from 1100 to 1675 deg C using a modified high temperature vacuum Bunsen calorimeter. The data were fitted to empirical equations from which the heat of transition and fusion, the heat capacity, and the related thermodynamic quantities were calculated. These results confirmed indications from other properties that europium and ytterbium metals are primarily in the divalert state. Small anomalies observed in europium and ytterbium were attributed to transitions between electronic states when some trivalent ions occur in these metals. The ertropy of the fcc-bcc transition for ytterbium was found to be approximately two- thirds that of the other rare-earth metals for which a close-packed to bodycertered cubic transformation was observed. (auth)
Date: July 26, 1961
Creator: Berg, J.R.; Spedding, F.H. & Daane, A.H.
Partner: UNT Libraries Government Documents Department


Description: A group of uranium specimens were irradiated under conditions in which some of the specimens were irradiated continuously while others were cycled in and out of a reactor. Although most of the specimens were irradiated under conditions in which they were entirely in the alpha phase, some were irradiated so that their centers were above alpha-phase temperatures. Both highly textured material (300 deg C rolled) and nomimally randomly oriented material (300 deg C rolled and beta-quenched) were studied. It appeared that irradiation cycling of both types of material may result in greater elongation than would be anticipated on the assumption that the effects of irradiation and thermal cycling acting alone were additive. The material rolled at 300 deg C showed no external effects due to central irradiation temperatures being above those limiting the alpha phase. However, betaquenched material, which was irradiated so that central temperatures were above those required for stability of the alpha phase, developed severe distortions which were greater under cycling conditions. It was also noted that 300 deg C rolled uranium begins to elongate under irradiation at burnups as low as 0.0002 a/o (2 Mwd/t). (auth)
Date: April 1, 1959
Creator: Kittel, J.H.
Partner: UNT Libraries Government Documents Department

DIMENSIONAL INSTABILITY OF URANIUM--II. Second Annual Progress Report, January 1, 1956 to June 30, 1957

Description: The mechanism of dimensional instability of irradiated uranium is under investigation. In order to confirm an assumption of the diffusion theory, the magnitude of diffusion anisotropy in alpha-uranium single crystals is being determined by measurement of the diffusion coefficients along the principal directions. Progress made in working out procedures for the preparation of uranium single crystals, preparation of the diffusion couples, measurement of valid concentration-penetration data in very thin diffusion zones by sectioning, and measurement of surface concentrations by means of nuclear tracking emudsions is discussed. Also, in-pile experiments are being designed to further clarify the nature of growth under irradiation. (auth)
Date: February 15, 1958
Creator: Resnick, R.; Castleman, L.S. & Seigle, L.
Partner: UNT Libraries Government Documents Department


Description: Diffusion coefficients for hydrogen in beta zirconium were determined from permeation rates in the range 650 to 850 deg C. Both the steady-state method, which is dependent upon the hydrogen concentration, and the time-lag method, which is independent of hydrogen concentration, were employed to obtain diffusion data. Zirconium disks, 0.03 to 0.1 cm thick and varying in hydrogen concentration from 9 to 33 at.%, were used to measure permeation rates. The diffusion coefficients determined by the steady-state and time-lag methods on samples of differing thickness were in agreement. It was concluded that the permeation process was diffusion controlled. The diffusion coefficients were found to be independent of concentration and can be expressed by D = 6.14 x 10/ sup 4/ exp (--45,900/RT). (auth)
Date: August 25, 1959
Creator: Albrecht, W.M. & Goode, W.D. Jr.
Partner: UNT Libraries Government Documents Department

Annihilation of Nuclei by Displacement Spikes

Description: At an Octcber, 1957 meeting between USAEC, AECL, and Bettis personnel, the theoretical aspects of the radiation effects on the gamma red and alpha + gamma /sub 2/ transformation in U-Nb alloys were discussed. A theoretical model is presented which involves the annihilation of nuclei of the new phase by the action of displacement spikes. (W.D.M.)
Date: November 1, 1957
Creator: Thomas, D. E.
Partner: UNT Libraries Government Documents Department


Description: A new method of introducing predetermined quantities of hydrogen into zirconium was developed and evaluated. The procedure is simple, effective, and inherently good in preverting oxygen and nitrogen contamination. Zirconium samples containing four levels of dissolved hydrogenated to 100, 300, 3500, and 7700 ppm hydrogen. Dissolved oxygen was found to decrease hydrogen absorption in both the alpha and beta modifications of zirconium. The effect of hydrogen on density, hardness, and microstructure was determined. X-ray-diffraction measurements were also obtained. (auth)
Date: May 26, 1958
Creator: Kearns, J.J.
Partner: UNT Libraries Government Documents Department

Alpha Ferric Oxide: Low Temperature Heat Capacity and Thermodynamic Functions

Description: ABS>The heat capacity of synthetic alpha ferric oxide was determined at 5 to 350 K. The experimental technique is described, and the heat capacity and molal thermodyamic functions are tabulated. The heat capacity vs. temperature is shown graphically. (J.R.D.)
Date: January 1, 1957
Creator: Gronvold, F. & Westrum, E. F., Jr.
Partner: UNT Libraries Government Documents Department