Observation of lattice and grain-boundary dislocations in UO$sub 2$ deformed at high temperatures

Journal Article · Mon Oct 01 04:00:00 EDT 1973 · J. Nucl. Mater., v. 48, no. 3, pp. 317-329

OSTI ID:4428904

Yust, C S; Roberts, J T.A.

The microstructure of a series of deformed, polycrystalline UO/sub 2/ specimens was studied by transmission electron microscopy. The lattice and grain boundary dislocation structures observed correlate with three temperature regimes of deformation. At temperatures below the brittle-to-ductile transition temperature, T/sub c/, the specimen is completely brittle and all grains are essentially free of dislocations. The grain boundary structures observed in these brittle specimens are very regular in appearance. In the temperature range between the high-temperature transition, T/sub t/, and T/sub c/, where small degrees of plastic deformation are recorded prior to fracture, the first evidence of dislocation activtty within the grains is noted, while the boundary structures remain regular. Above T/sub t/, appreciable plasticity occurs prior to fracture and extensive dislocation network formation occurs in the grains of the polycrystal. In addition, the structures in the grain boundaries become irregular in appearance. A qualitative discussion of the deformation process in polycrystalline UO/sub 2/ is derived from the observations of this study. (14 figures) (auth)

• Research Organization: Oak Ridge National Lab., TN
• NSA Number: NSA-29-008236
• OSTI ID: 4428904
• Journal Information: J. Nucl. Mater., v. 48, no. 3, pp. 317-329, Journal Name: J. Nucl. Mater., v. 48, no. 3, pp. 317-329; ISSN JNUMA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

*URANIUM DIOXIDE-- DISLOCATIONS
CRYSTAL LATTICES
DEFORMATION
ELECTRON MICROSCOPY
GRAIN BOUNDARIES
MICROSTRUCTURE
N50130* --Metals
Ceramics
& Other Materials--Ceramics & Cermets--Properties
Structure & Phase Studies
POLYCRYSTALS
TEMPERATURE DEPENDENCE
TRANSITION TEMPERATURE
VERY HIGH TEMPERATURE