TRANSFORMATIONS IN URANIUM ALLOYS WITH HIGH SOLUTE SOLUBILITY IN THE B.C.C. GAMMA PHASE. PART I. PRELIMINARY OBSERVATIONS ON THE "BANDED STRUCTURES" PRODUCED BY NON EQUILIBRIUM TRANSFORMATIONS IN URANIUM ALLOYS.


Book Description

The high-temperature body-centered cubic gamma phase in uranium alloys with approximately 10 at.% titanium, niobium, zirconium, or molybdenum can be rendered metastable under critical cooling conditions; it may transform thence by a shear mechanism to form a characteristic banded structure or by a nucleation and growth process to equiaxed grains. These decomposition structures with differing metallographic appearances give similar x-ray patterns. The structures are designated "distorted alpha " since the patterns correspond to a contraction in the b-direction of the normal ortho rhombic alpha cell. The formation of these metastable structures is apparently dependent upon composition, cooling rate, and the effect of the solute element on the incubation period and decomposition rate of the metastable gamma phase. (auth).







Transformations in Uranium Alloys with High Solute Solubility in the B.C.C. [gamma] Phase. Part 1. Preliminary Observations on the '' Banded Structures'' Produced by Non-equilibrium Transformations in Uranium Alloys


Book Description

The high-temperature body-centered cubic [gamma] phase in uranium alloys with approximately 10 at % titanium, niobium, zirconium, or molybdenum can be rendered metastable under critical cooling conditions; it may transform thence by a shear mechanism to form a characteristic banded structure or by a nucleation and growth process to equiaxed grains. These decomposition structures with differing metallographic appearances give similar x-ray patterns. The structures are designated ''distorted [alpha] '' since the patterns correspond to a contraction in the b-direction of the normal orthorhombic [alpha] cell. The formation of these metastable structures is apparently dependent upon composition, cooling rate, and the effect of the solute element on the incubation period and decomposition rate of the metastable [gamma] phase. (auth).




Reactor Core Materials


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Reactor Materials


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Elemental Solubility Tendency for the Phases of Uranium by Classical Models Used to Predict Alloy Behavior


Book Description

Traditional alloy theory models, specifically Darken-Gurry and Miedema's analyses, that characterize solutes in solid solvents relative to physical properties of the elements have been used to assist in predicting alloy behavior. These models will be applied relative to the three solid phases of uranium: alpha (orthorhombic), beta (tetragonal), and gamma (bcc). These phases have different solubilities for specific alloy additions as a function of temperature. The Darken-Gurry and Miedema models, with modifications based on concepts of Waber, Gschneider, and Brewer will be used to predict the behavior of four types of solutes: 1) Transition metals that are used for various purposes associated with the containment as alloy additions in the uranium fuel 2) Transuranic elements in the uranium 3) Rare earth fission products (lanthanides) 4) Transition metals and other fission products Using these solute map criteria, elemental behavior will be predicted as highly soluble, marginally soluble, or immiscible (compound formers) and will be used to compare solute effects during uranium phase transformations. The overlapping of these solute maps are convenient first approximation tools for predicting alloy behavior.