A Contribution to the Structural and Kinetic Study of the Slow Transformation of an Iron or Uranium Alpha Crystal; CONTRIBUTION A L'ETUDE STRUCTURALE ET CINETIQUE DE LA TRANSFORMATION LENTE D'UN CRISTAL DE FER ALPHA OU D'URANIUM ALPHA

Thesis/Dissertation · Wed Dec 17 04:00:00 EST 1958

OSTI ID:4187341

Donze, G

ABS>A curious phenomenon of regeneration of an iron or uranium alpha crystal in the double transformation of iron or uranium alpha yields gamma yields alpha and alpha yields beta yields alpha , respectively, was studied. This phenomenon does not occur with very pure metals, but only in the case of metals containing impurities, and more particularly, conWaning carbon. The monocrystal is not regenerated unless care is taken not to exceed final transformation temperatures by more than a few degrees. The same phenomenon is encountered in polycrystalline compounds: the orientation of the crystals is maintained, though the respective grain positions ("joints") are considerably displaced. Kinetic study of the transformation at cooling, on the one band, and the analysis of the texture at the gamma phase (iron) on the other, show that regeneration results from the conservation of the phase alpha germs at the high temperature phase. They appear to be relatively stable, for at the end of 24 hours at the experiment temperature, they had retained their properties. Study of the twin crystals of gamma iron engendered by the transformation alpha yields gamma demonstrated that there is no orientation relationship in the transformation: alpha yields gamma of pure iron. Thanks to the production of an epitaxic oxyde film on the surface of gamma iron, we were able to evidence a new type of iron tansformation twinned crystal which gross in one direction (110) and is in contact also at 110. Formed of very thin lamina, these crystals are very instable and become penetrants, each element, much larger, consisting of the increased thickness of a certain number of lamina. (auth)

• Research Organization: France. Commissariat a l'Energie Atomique, Paris
• NSA Number: NSA-14-009768
• OSTI ID: 4187341
• Report Number(s): CEA-1107
• Country of Publication: France
• Language: English

Related Subjects

ALLOTROPY
CARBON
COOLING
CRYSTALS
EXPANSION
FILMS
GRAIN SIZE
HIGH TEMPERATURE
IMPURITIES
IRON
IRON-ALPHA
IRON-GAMMA
LAMINAC
LATTICES
METALS, CERAMICS, AND MATERIALS
MONOCRYSTALS
OXIDES
REACTION KINETICS
STABILITY
SURFACES
TEMPERATURE
THERMODYNAMICS
THICKNESS
TWINNING
URANIUM
URANIUM-ALPHA
URANIUM-BETA