Author: J. W. AndersonPublisher:
ISBN:
Category : Phase transformations (Statistical physics)
Languages : en
Pages : 62
Book Description
Studies on the Alpha-to-beta and Beta-to-alpha Phase Transformations of Plutonium
Author: J. W. AndersonPublisher:
ISBN:
Category : Phase transformations (Statistical physics)
Languages : en
Pages : 62
Book Description
The Beta-alpha and Alpha-beta Transformations in Plutonium Under Applied Stresses
Author: R. D. NelsonPublisher:
ISBN:
Category : Plutonium
Languages : en
Pages : 40
Book Description
Transformation Kinetics of Plutonium
Author: R. D. NelsonPublisher:
ISBN:
Category : Chemical kinetics
Languages : en
Pages : 126
Book Description
Transformation Kinetics of Plutonium. Part I. a Study of the Beta to Alpha and Alpha to Beta Transformations
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
The transformation kinetics of alpha and beta plutoniunn were determined by using a fluid displacement technique. The rate of formation of the alpha phase from the beta phase was determined after beta heat treating and allowing the sample to transform isothermally in the alpha range. Isothermal reaction curves were obtained from --78 to +90 d C.A time- temperaturetransformation curve showed the maximum rate of transformation to be approximately --20 d C. The beta phase did not transform completely to the alpha when the transformation was allowed to take place isothermally. A relationship between the fraction untransformed beta and the transformation temperature has been established. Isothermal reaction curves and a time- temperature-transformation curve of the alpha at 200 deg C an - BETA transformation were obtained. Portions of the timetransformation curves of the BETA at 200 deg C an alpha transformation of four purities were plotted. The effects of beta heat treating times and temperatures were studied. Photomicrographs of a specimen having transformed from the beta to the alpha phase at different rates of transformation are presented. (auth).
Investigation of the Stresses Induced During the Beta-to-alpha Phase Transformation in Unalloyed Plutonium
Author: Brent J. BeerPublisher:
ISBN:
Category : Phase rule and equilibrium
Languages : en
Pages : 282
Book Description
Transformation Kinetics of Plutonium. Part II. a Study of the Gamma to Beta to Alpha and Alpha to Beta to Gamma Transformations
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book 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).
Supplement to "Studies on the Equilibrium Temperature for the Plutonium Alpha-Beta Transformation."
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 23
Book Description
The cited paper presents data which establishes the equilibrium temperature for the alpha-beta transformation of Pu at 117.0 ±0.5°C. This was observed by following the electrical resistance change in thin, high purity, mixed-phase specimens as they were thermally cycled near the transformation temperature. As expected the time required for small phase changes near the equilibrium temperature was long. Data regarding the mechanisms of the alpha-beta and beta-alpha transformations or rates as a function of temperature were not presented.
Kinetics of the Beta-alpha Transformation in Pure Plutonium
Author: The Kinetics of the Beta to Alpha Transformation in Unalloyed Plutonium Using Differential Scanning Calorimetry
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Differential scanning calorimetry measurements, both isothermal and on cooling, were made during the [beta] [yields] [alpha] transformation of unalloyed plutonium. The calorimetric measurements, because they directly measure the rate of heat flow, provide a direct quantitative measure of the rate of the reaction. Isothermal measurements at temperatures from 56[degree] to 68[degree]C showed that the reaction required incubation times, presumably for nucleation of the alpha phase, of from 300 to 550 seconds. The reaction rate increased with decreasing temperature in agreement with results of prior studies. The measured value for the heat of the reaction also corroborated earlier findings. The fraction-transformed curves were analyzed using the Johnson, Mehl, Avrami model. Analysis showed clearly that the reaction kinetics do not fit this model. The Avrami exponent, instead of being constant as predicted, decreased continuously (by more than a factor of four) during the first 80% of the reaction. Possible reasons for this apparent deviation from classical transformation kinetics are discussed. Measurements in the temperature-scanning mode were made on a sample consisting of ten separate pieces of plutonium. With successive cooling cycles through the [beta] [yields] [alpha] transformation, the heat release peak changed in shape, width, and position. This effect is believed to be due to changes in the residual stresses in different pieces of the sample.
Author: