Metastability of Alpha Plutonium


Book Description

The metastability of alpha plutonium above the [alpha] [r-equilibrium] [beta] equilibrim transformation temperature (112 C) was studied by metallographic techniques. The purpose of this study was to extend the previous work on the [alpha] [yields] [beta] transformation which was accomplished using fluid displacement techniques[sup 1] and to obtain a basis for determining the length of time the alpha phase is stable at high temperatures. Approximate isothermal reaction curves were determined experimentally and an [alpha] [yields] [beta] time- temperature-transformation (T-T-T) curve was derived.




Metastability and Delta-Phase Retention in Plutonium Alloys Final Report of LDRD Project 01-ERD-029


Book Description

The {delta} to {alpha}' phase transformation in Pu-Ga alloys is intriguing for both scientific and technological reasons. On cooling, the ductile fcc {delta}-phase transforms martensitically to the brittle monoclinic {alpha}'-phase at approximately -120 C (depending on composition). This exothermic transformation involves a 20% volume contraction and a significant increase in resistivity. The reversion of {alpha}' to {delta} involves a large temperature hysteresis beginning just above room temperature. In an attempt to better understand the underlying thermodynamics and kinetics responsible for these unusual features, we have investigated the {delta} {leftrightarrow} {alpha}' phase transformations in a Pu-0.6 wt% Ga alloy using a combination of experimental and modeling techniques.










Growth of Alpha Plutonium Crystals from Melts Under Extreme Pressure


Book Description

Large-grained alpha plutonium has been prepared by slow solidification of melts under pressure of about 60 kbars. The technique opens the way to produce single crystals of alpha plutonium, and to obtain basic information previously unattainable.




Evidence that Alpha-phase Plutonium is a 9R Martensite


Book Description

We suggest that there may be different precursors of the alpha phase of plutonium in the martensitic delta .-->. .cap alpha. transformation, depending upon whether the metastable delta-phase alloy is compressed or cooled below ambient. The precursors may be either the orthorhombic (.gamma.) phase, which is observed, or an hcp structure which can transform rapidly to alpha. We postulate that the martensitically formed alpha phase of plutonium (delta .-->. .cap alpha. or .beta. .-->. .cap alpha.) has the characteristics of a modified 9R martensite. The development of such a structure can explain the anomalous low-temperature physical property behavior of both .cap alpha.-Pu and its delta-phase stabilized alloys.










Plutonium Abstracts


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Plutonium


Book Description