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Test of a NbTi Superconducting Quadrupole Magnet Based on Alternating Helical Windings

Description: It has been shown that by superposing two solenoid-like thin windings, that are oppositely skewed (tilted) with respect to the bore axis, the combined current density on the surface is cos({theta})-like and the resulting magnetic field in the bore is a pure dipole field. Following a previous test of such a superconducting dipole magnet, a quadrupole magnet was designed and built using similar principles. This paper describes the design, construction and test of a 75 mm bore 600 mm long superconducting quadrupole made with NbTi wire. The simplicity of the design, void of typical wedges, end-spacers and coil assembly, is especially suitable for future high field insert coils using Nb{sub 3}Sn as well as HTS wires. The 3 mm thick coil reached 46 T/m but did not achieve its current plateau.
Date: August 16, 2009
Creator: Caspi, S.; Trillaud, F.; Godeke, A.; Dietderich, D.; Ferracin, P.; Sabbi, G. et al.
Partner: UNT Libraries Government Documents Department

The mechanical response of a uranium-nobium alloy: a comparison of cast versus wrought processing

Description: A rigorous experimentation and validation program is being undertaken to create constitutive models that elucidate the fundamental mechanisms controlling plasticity in uranium-6 wt.% niobium alloys (U-6Nb). The first, 'wrought', material produced by processing a cast ingot I'ia forging and forming into plate was studied. The second material investigated is a direct cast U-6Nb alloy. The purpose of the investigation is to detennine the principal differences, or more importantly, similarities, between the two materials due to processing. It is well known that parameters like grain size, impurity size and chemistry affect the deformation and failure characteristics of materials. Metallography conducted on these materials revealed that the microstructures are quite different. Characterization techniques like tension, compression, and shear were performed to find the principal differences between the materials as a function of stress state. Dynamic characterization using a split Hopkinson pressure bar in conjunction with Taylor impact testing was conducted to derive and thereafter validate constitutive material models. The Mechanical Threshold Strength Model is shown to accurately capture the constitutive response of these materials and Taylor cylinder tests are used to provide a robust way to verify and validate the constitutive model predictions of deformation by comparing finite element simulations with the experimental results. The primary differences between the materials will be described and predictions about material behavior will be made.
Date: January 1, 2009
Creator: Cady, Carl M; Gray, Ill, George T; Cerreta, Ellen K; Aikin, Robert M; Chen, Shuh - Rong; Trujillo, Carl P et al.
Partner: UNT Libraries Government Documents Department


Description: During the examination of the pins from in-pile autoclave L6Z-114 it was noted that each of the doublenotched pins exhibited areas of increased corrosion while the exact duplicate single-notched pins did not. The two pairs of Zircaloy- 2 pins were identical in structure and thus the noted differencs in corrosive attack cannot be attributed to this factor. In the Zr-1.5% Sn--15% Nb pins the corrosive attack did not seem dependent on the slight variation in structure of the pins. (W. L.H.)
Date: February 1, 1958
Creator: Richt, A.E.
Partner: UNT Libraries Government Documents Department


Description: The current-carrying capacity of Nb- Zr wire was studied under conditions of swept magnetic field and fixed wire current and of fixed magnetic field and swept wire current. The effects of wire movement, thermal environment, copper coating of the wire, and rate of sweep of wire current or magnetic field were determined for these test conditions. (auth)
Date: January 1, 1963
Creator: Laverick, C
Partner: UNT Libraries Government Documents Department

Annihilation of Nuclei by Displacement Spikes

Description: At an Octcber, 1957 meeting between USAEC, AECL, and Bettis personnel, the theoretical aspects of the radiation effects on the gamma red and alpha + gamma /sub 2/ transformation in U-Nb alloys were discussed. A theoretical model is presented which involves the annihilation of nuclei of the new phase by the action of displacement spikes. (W.D.M.)
Date: November 1, 1957
Creator: Thomas, D. E.
Partner: UNT Libraries Government Documents Department

Alloys of Uranium with Zirconium, Chromium, Columbium, Vanadium, and Molybdenum

Description: Abstract: Information on five uranium binary alloy systems has been surveyed. These systems are the alloys of uranium with zirconium, chromium, columbium, vanadium, and molybdenum. The equilibrium diagrams are discussed, and where available, data have been included on diffusion studies, cladding experiments, and mechanical properties.
Date: June 19, 1952
Creator: Saller, Henry A. & Rough, Frank A.
Partner: UNT Libraries Government Documents Department

Transformations in uranium-base alloys : summary report, December 14, 1955 - March 31, 1957

Description: From abstract: "Transformation kinetics of binary U -Nb and ternary U-Nb-base alloys were investigated. Additions included zirconium, chromium, titanium, silicon, nickel, nnthenium, and vanadium. Encapsulated samples were given a homogenizstion anneal at 1000 or 1100/sup o/C, water-quenched from 906/sup o/C to retain the phase, and reheated to temperatures between 360 and 600/sup o/C. The metastability of the phase was examined by metallographic, hardness, resistometric, dilatometric and x-ray-diffraction techniques. The U -Nb system is characterized by a monotectoid decomposition of the high temperature allotrope at about 645/sup o/C to form alpha and ₂, a niobium-rich cubic structure. Decomposition in U-Nb and in most U-Nb-X alloys occurred by a continuous precipithtion of alpha from the body-centered cubic phase with a resultant enrichment in niobium of until the equilibrium ₂ composition was reached. In the U-Nb-Ti and U-Nb-V systems, alpha and /sub 2/ were coprecipitated. Annealing at 550 and 600/sup o/C produced decomposition products which, in most materials, originated at the grain boundaries; a fine precipitate which initiated throughout the matrix was observed at lower annealing temperatures. Increasing the niobium content resulted in greatly increased stability. The following elements added to a U-Nb base were found to retard transformation of the phase: zirconium, chromium, ruthenium, and vanadium. Additions of titanium, silicon, and nickel produced alloys which were less stable than the U-Nb base to which they were added. Cold-working a U-7 wt. % Nb-2 wt. % Zr composition caused a more rapid transformation upon annealing at 360 and 450/ sup o/C, and the resulting microstructures were different. Continuous cooling transformation studies were conducted on U-10 wt. % Nb materials, solution annealed at 700 and 950°C, and cooled at various linear rates to temperatures between 300 and 600/sup o/C. Cooling rates between 8.5 and 14.5/sup o/C per minute were required to prevent transformation of ...
Date: 1957
Creator: Parry, Sidney J. S.; Holtz, F. C. & Van Thyne, R. J.
Partner: UNT Libraries Government Documents Department

Ultrafine fully-lamellar structures in two-phase {gamma}-TiAl alloys

Description: Special ultrafine fully lamellar microstructures have been found recently in {gamma}-TiAl alloys with 46-48% Al processed or heat treated above the {alpha}-transus temperature (T{alpha}). Hot extrusion above T{alpha} also produces a refined colony or grain size. Refined-colony/ultrafine-lamellar (RC/UL) microstructures produce an excellent combination of RT ductility and high-temperature strength in Ti-47Al-2Cr-2Nb (at.%) alloys. UL structures also have regularly alternating {gamma} and {alpha}{sub 2} lamellae, such that they are dominated by {gamma}/{alpha}{sub 2} interfaces with relatively few {gamma}/{gamma} twin boundaries. Focus of this study is on how changes in processing parameters or alloy composition affect formation of the UL structure, particularly the {alpha}{sub 2} component.
Date: December 31, 1996
Creator: Maziasz, P.J. & Liu, C.T.
Partner: UNT Libraries Government Documents Department

Density Prediction of Uranium-6 Niobium Ingots

Description: The densities of uranium-6 niobium (U-Nb) alloys have been compiled from a variety of literature sources such as Y-12 and Rocky Flats datasheets. We also took advantage of the 42 well-pedigreed, homogeneous baseline U-Nb alloys produced under the Enhanced Surveillance Program for density measurements. Even though U-Nb alloys undergo two-phase transitions as the Nb content varies from 0 wt. % to 8 wt %, the theoretical and measured densities vary linearly with Nb content. Therefore, the effect of Nb content on the density was modeled with a linear regression. From this linear regression, a homogeneous ingot of U-6 wt.% Nb would have a density of 17.382 {+-} 0.040 g/cc (95% CI). However, ingots produced at Y-12 are not homogeneous with respect to the Nb content. Therefore, using the 95% confidence intervals, the density of a Y-12 produced ingot would vary from 17.310 {+-} 0.043 g/cc at the center to 17.432 {+-} 0.039 g/cc at the edge. Ingots with larger Nb inhomogeneities will also have larger variances in the density.
Date: April 15, 2003
Creator: D.F.Teter; Tubesing, P.K.; D.J.Thoma & E.J.Peterson
Partner: UNT Libraries Government Documents Department

ALCHEMI of niobium dichrome/vanadium C15 Laves phase

Description: 33Nb42Cr25V was prepared by arc melting and annealing at 1400 C for 120 hr. Energy-dispersive x-ray spectra were collected over a range of {l_brace}400{l_brace} excitations between symmetry and beyond {l_brace}12 0 0{l_brace}. Results show that at least qualitatively V substitutes for Cr. Therefore, electronic effects must be more important than size effects in this case.
Date: May 1, 1996
Creator: Kotula, P.G.; Chu, Fuming; Mitchell, T.E.; Anderson, I.M. & Bentley, J.
Partner: UNT Libraries Government Documents Department

Microstructures and Mechanical Properties of Two-Phase Alloys Based on NbCr(2)

Description: A two-phase, Nb-Cr-Ti alloy (bee+ C15 Laves phase) has been developed using several alloy design methodologies. In effort to understand processing-microstructure-property relationships, diffment processing routes were employed. The resulting microstructure and mechanical properties are discussed and compared. Plasma arc-melted samples served to establish baseline, . . . as-cast properties. In addition, a novel processing technique, involving decomposition of a supersaturated and metastable precursor phase during hot isostatic pressing (HIP), was used to produce a refined, equilibrium two-phase microstructure. Quasi-static compression tests as a ~ function of temperature were performed on both alloy types. Different deformation mechanisms were encountered based upon temperature and microstructure.
Date: December 7, 1998
Creator: Cady, C.M.; Chen, K.C.; Kotula, P.G.; Mauro, M.E. & Thoma, D.J.
Partner: UNT Libraries Government Documents Department

Uniaxial Compression Experiments on PZT 95/5-2Nb Ceramic: Evidence for an Orientation-Dependent, ''Maximum Compressive Stress'' Criterion for Onset of the F(R1)()A(O) Polymorphic Phase Transformation

Description: Some time ago we presented evidence that, under nonhydrostatic loading, the F{sub R1} {r_arrow} A{sub O} polymorphic phase transformation in unpoled PZT 95/5-2Nb ceramic began when the maximum compressive stress equaled the hydrostatic pressure at which the transformation otherwise took place. More recently, we showed that this simple stress criterion did not apply to nonhydrostatically compressed, poled ceramic. However, unpoled ceramic is isotropic, whereas poled ceramic has a preferred crystallographic orientation and is mechanically anisotropic. If we further assume that the transformation depends not only on the magnitude of the compressive stress, but also its orientation relative to some feature(s) of PZT 95/5-2Nb's crystallography, then these disparate results can be qualitatively resolved. In this report, we first summarize the existing results for unpoled and poled ceramic. Using our orientation-dependent hypothesis and these results, we derive simple arithmetic expressions that accurately describe our previously-observed effects of nonhydrostatic stress on the transformation of unpoled ceramic. We then go on to test new predictions based on the orientation-dependent model. It has long been known that the transformation can be triggered in uniaxial compression: the model specifically requires a steadily increasing axial stress to drive the transformation of a randomly-oriented polycrystal to completion. We show that when the stress is held constant during uniaxial compression experiments, the transformation stops, supporting our hypothesis. We close with a discussion of implications of our model, and ways to test it using poled ceramic.
Date: January 1, 1999
Creator: Carlson, L.W.; Grazier, J.M.; Holcomb, D.J.; Montgomery, S.T. & Zeuch, D.H.
Partner: UNT Libraries Government Documents Department

Orientation relationships in the system Nb-NbCr{sub 2}

Description: Two phase alloys are considered promising for structural applications. The orientation relationships between the phases can contribute to the mechanical properties of the material. A niobium-niobium/chromium{sub 2} eutectic alloy was prepared and the microstructure characterized.
Date: May 1, 1997
Creator: Kotula, P.G.; Chen, K.C. & Thoma, D.J.
Partner: UNT Libraries Government Documents Department

Plastic Flow Characteristics of Uranium-Niobium as a Function of Strain Rate and Temperature

Description: The stress-strain response of uranium-niobium alloys as a function of temperature, strain-rate and stress-state was investigated. The yield and flow stresses of the U-Nb alloys were found to exhibit a pronounced strain rate sensitivity, while the hardening rates were found to be insensitive to strain rate and temperature. The overall stress-strain response of the U-6Nb exhibits a sinusoidal hardening response, which is consistent with multiple deformation modes and is thought to be related to shape-memory behavior.
Date: January 4, 1999
Creator: Cady, C.M.; Gray, G.T. III; Hecker, S.S; Thoma, D.J.; Korzekwa, D.R.; Patterson, R.A. et al.
Partner: UNT Libraries Government Documents Department