STRUCTURAL CHANGES OF URANIUM DURING THERMAL CYCLING

Journal Article · Sun Jul 01 00:00:00 EDT 1962 · Jaderna energie

OSTI ID:4774594

Slancar, F; Novotny, V

An evaluation was made of the structural changes of uranium by metallographic methods and an explanation of the mechan1sm of the changes is given. Commercial quality natural uranium in the cast, rolled, rotary forged, and extruded state was used. Thermal cycling in the alpha phase was carried out in the temperature range of 50--550 deg C up to 2000 thermal cycles (t. c.). Structural changes were investigated statistically by means of special instruments and of normal metallographic microscope. The mechanism of structural changes was investigated with the aid of the high temperature microscope in individual phases of the thermal cycles. Special attention was given to grain decay during thermal cycling, and to the origin of microcracks. Original grain of uranium decays during thermal cycling. The percentage of decayed grains varied directly with the number of cycles up to 600 t. c. The grain size varied no more above this number of cycles. From the analysis of microcrack positions it was evident that they were on the grain boundary. The origin and spreading of microcracks may be influenced by inclusions, namely of UO-type, by complexes U (OCN) and other. After further thermal cycling microcracks originated at the inclusions were spread into matrix material. The microcrack number and length varied directly with the number of thermal cycles. The results demonstrate a substantial influence of the kind of uranium production on the origin of microcracks. (auth)

• Research Organization: Originating Research Org. not identified
• NSA Number: NSA-16-033503
• OSTI ID: 4774594
• Journal Information: Jaderna energie, Vol. Vol: 8; Other Information: Orig. Receipt Date: 31-DEC-62
• Country of Publication: Country unknown/Code not available
• Language: Czech

Related Subjects

METALS, CERAMICS, AND OTHER MATERIALS
ALLOTROPY
CASTING
COMPLEXES
CONFIGURATION
CRACKS
DEFECTS
EXTRUSION
FORGING
GRAIN BOUNDARIES
GRAIN SIZE
HEAT TREATMENTS
HIGH TEMPERATURE
IMPURITIES
INCLUSIONS
METALLOGRAPHY
MICROSCOPY
PRODUCTION
ROLLING
ROTATION
STATISTICS
TEMPERATURE
URANIUM
URANIUM CARBIDES
URANIUM NITRIDES
URANIUM OXIDES
URANIUM-ALPHA
VARIATIONS