Phase transformations in uranium, plutonium, and neptunium

Rechtien, James J.; Nelson, R.D.

doi:10.1007/bf02644575

Cited by 29 publications

(11 citation statements)

References 44 publications

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“…This latter quantity that may be obtained from equilibrium phase diagram (lever rule) or may be set as an internal reference value which is obtained under very slow heating or cooling conditions. A rough estimate of τ (assumed to be β independent in the trial estimation) can be obtained from the experimental data using (7). Thus (∂X/∂t) β is readily obtained.…”

Section: A Simple Non-additive Model For Non-isothermal Phase Changementioning

confidence: 99%

“…There is one evidences in metallurgical literature, which suggest that on rapid heating or cooling conditions, classical nucleation and growth mediated phase changes are inhibited and yield way to martensitic or displacive types. 6,7 From the experimental point of view, the heating or cooling rate dependence of transformation temperatures, in addition to the transformed fraction X(T), offer a valuable wholesome kinetic data set. It is generally the case that the transformation temperatures are highly nonlinear with respect to heating or cooling rate, and this tendency is exhibited more remarkably by the transformation finish (T f ) temperatures.…”

Section: Non-isothermal Phase Changementioning

confidence: 99%

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Kinetics of solid state phase transformations: Measurement and modelling of some basic issues

Raju

Mohandas

2010

J Chem Sci

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A brief review of the issues involved in modelling of the solid state transformation kinetics is presented. The fact that apart from the standard thermodynamic parameters, certain path variables like heating or cooling rate can also exert a crucial influence on the kinetic outcome is stressed. The kinetic specialties that are intrinsic to phase changes proceeding under varying thermal history are enumerated. A simple and general modelling methodology for understanding the kinetics of non-isothermal transformations is outlined.

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Section: A Simple Non-additive Model For Non-isothermal Phase Changementioning

confidence: 99%

Section: Non-isothermal Phase Changementioning

confidence: 99%

Kinetics of solid state phase transformations: Measurement and modelling of some basic issues

Raju

Mohandas

2010

J Chem Sci

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“…principles electronic structure models; the first because of the difficulties in working with Pu, [3][4][5][6] the second because Pu electrons straddle the itinerant/localized boundary, frustrating understanding. [7][8][9][10][11] Lacking essential measurements for a very challenging element further distances understanding.…”

mentioning

confidence: 99%

Temperature dependence of elastic moduli of polycrystalline β plutonium

et al. 2011

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The elastic moduli of pure polycrystalline beta plutonium were measured over its full range of existence (417 K to 491 K) using resonant ultrasound spectroscopy. The Debye temperature (138 K), Poisson's ratio (0.28), Grüneisen parameter (2.3), and the zerotemperature atomic volume (21.2 Å 3 ) were computed from the measurements. Both bulk and shear moduli decrease smoothly on warming with expected discontinuities at the phase boundaries. The shear modulus is surprisingly nearly the same for beta and gamma Pu. The temperature dependence of bulk moduli for beta Pu is, like gamma Pu, unusually small. Poisson's ratio shows very strong differences among alpha, beta, and gamma Pu indicating they are entirely different metals. The zero-temperature elastic moduli were computed for the three phases as well as for gallium-stabilized delta Pu (also measured by us) and compared to calculations.PACS numbers: 62.20. de, 63.70.+h, 65.40.G-, 62.20.dj

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“…a transformation in unalloyed plutonium has also been studied a great deal by a variety of techniques: dilatometry, differential scanning calorimetry (DSC), resistivity, X-ray diffraction, light microscopy and resonant ultrasound spectroscopy [20][21][22][23][24][25][26][27][28][29][30]. In spite of all this work, there is no accepted agreement on the mechanism of the transformation or even its nature.…”

Section: Is the B ! A Transformation Martensitic?mentioning

confidence: 99%