Microstructure and kinetics of the plutonium $beta$ $Yields$ $alpha$ and $gamma$ $Yields$ $alpha$ transformations

Conference · Wed Jan 01 04:00:00 EST 1975

OSTI ID:4142084

Allen, R P; Arrow Smith, H W

Supported-discharge cathodic etching and SEM examination techniques were developed for $alpha$-Pu and used to investigate the $alpha$ microstructures formed by the $beta$/sub $alpha$/ $Yields$ $alpha$ and $beta$/sub $gamma$/ $Yields$ $alpha$ transformations in high-purity extruded Pu at low and high $alpha$-phase temperatures ($beta$/sub $alpha$/ and $beta$/sub $gamma$/ are $beta$ formed from $alpha$ and $gamma$, respectively). Low (200$sup 0$K) $beta$/ sub $alpha$/ $Yields$ $alpha$ transformation temperatures produced $alpha$ with a grain size that was finer than that of the original extruded $alpha$ and substantially smaller than the grain size of the $alpha$ formed from $beta$/sub $gamma$/. At high $alpha$-phase temperatures (343 to 370$sup 0$K), $beta$/sub $alpha$/ transformed to $alpha$ by the surface nucleation and inward growth of colonies of columnar $alpha$ grains oriented radially with respect to the original nucleation site. The transformation kinetics could be correlated with the microstructural observations based on a correspondence between the long axes of the grains and the (010) direction of the monoclinic $alpha$-Pu structure. Significant changes in the size, shape, and orientation of the $alpha$ grains were noted with increasing transformation temperature. Conversely, the grain size of the $alpha$ formed from $beta$/sub $gamma$/ was essentially constant at all transformation temperatures. Metallographic evidence of the $gamma$ $Yields$ $alpha$ skip transformation or a significant change in the mode of the $gamma$ $Yields$ $alpha$ transformation was obtained by a comparison of the $alpha$ microstructures produced by quenching $gamma$ to high (362 to 368$sup 0$K) and low (200$sup 0$K) $alpha$-phase temperatures. (auth)

• Research Organization: Battelle Pacific Northwest Labs., Richland, Wash. (USA)
• DOE Contract Number: AT(45-1)-1830
• NSA Number: NSA-33-001237
• OSTI ID: 4142084
• Report Number(s): BNWL-SA--5328; CONF-750915--16
• Country of Publication: United States
• Language: English

Related Subjects

*PLUTONIUM-ALPHA-- PHASE TRANSFORMATIONS
*PLUTONIUM-BETA-- PHASE TRANSFORMATIONS
*PLUTONIUM-GAMMA-- PHASE TRANSFORMATIONS
360102* --Materials--Metals & Alloys--Structure & Phase Studies
ELECTRON MICROSCOPY
GRAIN ORIENTATION
MEDIUM TEMPERATURE
MICROSTRUCTURE
N50230* --Metals
Ceramics
& Other Materials--Metals & Alloys--Properties
Structure & Phase Studies