Comparative Study of the Allotropic Transformations in Iron and Uranium, and their Structural Consequences; ETUDE COMPAREE DES TRANSFORMATIONS ALLOTROPIQUES DE L'URANIUM ET DU FER ET DE DEURS CONSEQUENCES STRUCTURALES

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1958

OSTI ID:4247508

Lehr, P

The alpha yields BETA phase change in pure uranium and the alpha yields gamma phase change in pure iron follow a nucleation and growth process. The development of alpha nuclei during these transformations was studied by controlling, in an furnace with a temperature gradient, the slow and regular displacement of the interface between the two phases. In these conditions the number of alpha nuclei fommed can be limited, and large crystals elongated in the direction of the temperature gradient or eventually single crystals are obtained. The crystallographic orientition and the degree of perfection of the uranium and iron crystals were analyzed. The dilatometric behavior of unanium monocrystals was studied as a function of their crystallographic orientations. The expansion coefficients along the three principal axes of the orthorhombic alpha cell were measured. By passing through the alpha /4YY BETA or alpha yields gamma transformation points, it is possible to suppress all prior textures of the grain. water-quenching of uranium from the BETA phase gives a grain without preferred orientation and with a size small enough so that statistical compensation of the expansion anisotropy of each grain can be obtained. The stresses created by the rapid passage of the transformation point cause a recrystallization of the metal during further annealing of the alpha phase. The volume change, accompanying the alpha YY BETA transformation of uranium and the alpha yields gamma transformation of iron, produces, during the formation or the new phase nuclei and their subsequent growth, stresses large enough to produce a true deformation of the metal. The deformation characteristics, their structural consequences, and the effects of thermal cycling in the transformation range were analyzed both for uranium and iron. (tr- auth)

• Research Organization: France. Commissariat a l'Energie Atomique, Paris
• NSA Number: NSA-13-016972
• OSTI ID: 4247508
• Report Number(s): CEA-800
• Country of Publication: France
• Language: English

Related Subjects

ALLOTROPY
ALPHA PARTICLES
CONFIGURATION
CONTROL
CRYSTALLIZATION
CRYSTALS
DEFORMATION
DISTRIBUTION
EXPANSION
FURNACES
GRAIN SIZE
HEAT TREATMENTS
IRON
METALLURGY AND CERAMICS
MONOCRYSTALS
NUCLEATE BOILING
NUCLEI
QUENCHING
RECRYSTALLIZATION
STRESSES
SURFACES
THERMAL STRESSES
URANIUM
WATER