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(The relationship between microstructure and magnetic properties in high-energy permanent magnets characterized by polytwinned structures)

Description: This report summarizes the results of a study of the relationship between microstructure and magnetic properties in a unique genre of ferromagnetic material characterized by a polysynthetically twinned structure which arises during solid state transformation. These results stem from the work over a period of approximately 27 months of a nominal 3 year grant period. The report also contains a proposal to extend the research project for an additional 3 years. The polytwinned structures produce an… more
Date: January 1, 1992
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Magnetic excitations in transition-metal ferromagnets. Recent progress and future prospects on neutron scattering experiments

Description: A review is given on current neutron scattering experiments at Brookhaven National Laboratory on transition-metal ferromagnets Ni, Fe, Pd/sub 2/MnSn and MnSi. The scattering intensity in constant-energy scans, observed above T/sub c/ in all of these materials, exhibited a clear peak at finite momentum transfers. Using a simple scattering function with double-Lorentzian shape, we demonstrate that this peak is a manifestation of simple diffusive spin fluctuations. Experimental results of several … more
Date: January 1, 1984
Creator: Uemura, Y.J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Combined electrochemical/surface science investigations of Pt/Cr alloy electrodes

Description: Chromium addition improves the performance of carbon-supported Pt electrodes for oxygen reduction in phosphoric acid fuel cells. To clarify the role of chromium and its chemical nature at the electrode surface, we have performed a combined electrochemical/surface science investigation of a series of bulk Pt/sub x/Cr/sub (1-x)/ alloys (0 less than or equal to x less than or equal to 1). In this paper we report the surface characterization of the starting electrodes by XPS, electrochemical result… more
Date: January 1, 1985
Creator: Daube, K. A.; Paffett, M. T.; Gottesfeld, S. & Campbell, C. T.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Space nuclear safety and fuels program. Progress report

Description: This technical monthly report covers studies related to the use of /sup 238/PuO/sub 2/ in radioisotope power systems. These studies are conducted by Los Alamos National Laboratory for the Office of Coordination and Special Projects of the US Department of Energy. Because most of the studies discussed here are ongoing, results and conclusions may change as the work continues. Published reference of the results cited in this report should not be made without explicit permission from the person in… more
Date: January 1, 1982
Creator: Bronisz, S. E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Welding iridium heat-source capsules for space missions

Description: A remote computer-controlled welding station was developed to encapsulate radioactive PuO/sub 2/ in iridium. Weld quench cracking caused an interruption in production of capsules for upcoming space missions. Hot crack sensitivity of the DOP-26 iridium alloy was associated with low melting constituents in the grain boundaries. The extent of cracking was reduced but could not be eliminated by changes to the welding operation. An ultrasonic test was developed to detect underbead cracks exceeding a… more
Date: March 1982
Creator: Kanne, W. R., Jr.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Metastable phases produced by ion implantation in metals

Description: Experimental evidence for the formation of metastable phases in metals using ion implantation is reviewed. Ion channeling and transmission electron microscopy are the main experimental techniques which have been used to investigate these materials. For heavy metallic implanted species at low implanted concentrations (less than or equal to 1 at. percent), the materials are generally substitutional solid solutions, often exceeding equilibrium solid solubilities. At higher concentrations both meta… more
Date: January 1, 1977
Creator: Borders, J.A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Development and characterization of an improved Ir--0. 3% W alloy for space radioisotopic heat sources

Description: An Ir--0.3% W alloy has been doped with minor alloying additions to develop an improved cladding material for space radioisotopic heat sources operating at temperatures to 1450/sup 0/C. Tensile tests of a series of doped alloys at slow strain rates indicated that the DOP-4 alloy containing 40 Al, 30 Th, 80 Fe, 10 Ni, and 75 Rh ppm was most resistant to the brittle fracture associated with grain-boundary separation. In addition, the DOP-4 dopants raise the recrystallization temperature, and reta… more
Date: October 1, 1977
Creator: Liu, C.T. & Inouye, H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Fission-fragment-induced helium blistering of /sup 252/Cf-exposed surfaces

Description: Inner surfaces of a Pt-10% Rh capsule exposed at room temperature to alpha particles and fission fragments in a large /sup 252/Cf source showed many small blisters, with elongated configurations in some areas. Formation of the blisters was attributed to the fission-fragment-induced agglomeration of helium implanted by the alpha particles, coupled with a stress relieving transport of lattice atoms displaced by the fission fragments into the blister walls. Lateral and vertical elongation of the b… more
Date: January 1, 1977
Creator: McDonnell, W.R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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/sup 238/Pu fuel form processes. Quarterly report, April-June 1981

Description: An analytical program has been started to determine the cause of cracking in DOP-26 iridium alloy during welding of GPHS clad vent sets. Analyses revealed that (1) intergranular cracking in the interior weld bead occurs in the heat-affected zone adjacent to the arc quench taper and at weld edges, (2) grain surfaces exposed by cracking exhibit a characteristic ridge network topography, and (3) no elements that could cause hot shortness were detected in the ridge networks.
Date: December 1, 1981
Creator: Folger, R. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Neutron scattering studies of heavy Fermions. [CeAl/sub 3/, UBe/sub 13/, CeCu/sub 2/Si/sub 2/, CeCu/sub 6/, ThBe/sub 13/, UPt/sub 3/, U/sub 2/Zn/sub 17/]

Description: Heavy Fermions are f electron materials characterized by a large linear term in the low temperature specific heat and a large magnetic susceptibility at low temperatures. This implies that there is a narrow peak in the f electron density of states at the Fermi energy. Typical examples are CeAl/sub 3/, UBe/sub 13/, CeCu/sub 2/Si/sub 2/, CeCu/sub 6/, U/sub 2/Zn/sub 17/ and UPt/sub 3/. Neutron scattering measurements can play an important role in understanding the magnetic interactions in these sy… more
Date: January 1, 1985
Creator: Shapiro, S.M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Electrocatalytic activity and surface properties of tungsten bronzes

Description: The electrocatalytic activities of sodium tungsten bronzes, including high purity crystals, platinum doped crystals, and platinum plated crystals, have been measured for oxygen reduction in acid solution. In addition, a survey of the electrocatalytic activities and general electrochemical properties of other alkali tungsten bronzes, thalium tungsten bronze, and tungsten trioxide were investigated and compared to sodium tungsten bronze. All measurements were done on single crystals. Pure sodium … more
Date: December 1, 1977
Creator: Weber, M.F.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Light weight radioisotope heater unit (LWRHU): a technical description of the reference design

Description: The Light Weight Radioisotope Heater Unit (LWRHU), a new radioisotope heater unit for use in space missions, is a /sup 238/PuO/sub 2/-fueled unit designed to provide a thermal watt in dispersed locations on a spacecraft. The LWRHU is required to maintain the temperature of a component at a level where the component will function reliably in space. Two major constraints are placed on the unit's design; it must be as light as possible and must provide enough protection to immobilize the plutonium… more
Date: January 1, 1982
Creator: Tate, R.E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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On the causes of compositional order in the Ni sub c Pt sub (1-c) alloys

Description: We review, briefly, the arguments which gave rise to the current controversy concerning the origin of compositional order in Ni{sub c}Pt{sub 1-c} alloys. We note that strain fluctuations play an important role in determining the state of compositional order in this system and outline a theoretical framework that takes account of them. 29 refs., 4 figs.
Date: January 1, 1991
Creator: Gyorffy, B.L. (Bristol Univ. (United Kingdom). H.H. Wills Physics Lab.); Pinski, F.J. (Cincinnati Univ., OH (United States). Dept. of Physics); Ginatempo, B. (Messina Univ. (Italy). Ist. di Fisica Teorica); Johnson, D.D. (Sandia National Labs., Albuquerque, NM (United States)); Staunton, J.B. (Warwick Univ., Coventry (United Kingdom). Dept. of Physics); Shelton, W.A. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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/sup 238/Pu fuel-form processes. Quarterly report, January-March 1982

Description: Progress in the Savannah River /sup 238/Pu Fuel Form Program is summarized. Analytical studies of weld quench cracking in DOP-26 iridium alloy-clad vent sets are reported. Cracks that occur in the arc quench region of the girth welds on DOP-26 iridium alloy-clad vent sets (CVS) have been a problem in production of general-purpose heat sources (GPHS) in the Savannah River Plant (SRP) Plutonium Fuel Form (PuFF) Facility. Previous analytical work has shown that alloy grain boundaries in cracks hav… more
Date: July 1, 1982
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Itinerant f-electron behavior in Ce and U compounds

Description: The experimentally observed Fermi surface properties in URh/sub 3/, UIr/sub 3/, UGe/sub 3/, CeSn/sub 3/, CeB/sub 6/, U/sub 3/As/sub 4/, U/sub 3/P/sub 4/, and CeSb are reviewed. For the compounds with no magnetic order, band structure models of the Fermi surface geometry are confirmed and f-ligand hybridization is found to be dominant. For CeB/sub 6/, U/sub 3/As/sub 4/, and U/sub 3/P/sub 4/ the experiments show that both local moments and f hybridization are important. In CeSb new data can be ex… more
Date: April 1, 1985
Creator: Crabtree, G.W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Structural examination of iridium-based single-crystal preparations. [AlIr; IrSi]

Description: A high-temperature crystal growth experiment produced discrete single-crystal products of AlIr and IrSi. The preparation and examination of these phases is described within. This project is part of a materials compatibility study relating to radioisotopic heat sources. These heat sources are comprised of a PuO/sub 2/ fuel pellet encapsulated in an Ir alloy containment shell. Th is introduced as an additive within the Ir to maintain ductility. Si and P are picked up inadvertently in the fuel pro… more
Date: January 1, 1985
Creator: Axler, K.M. & Roof, R.B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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mu. /sup +/SR in amorphous spin glasses Pd/sub 75/Fe/sub 5/Si/sub 20/ and Pd/sub 75/Fe/sub 5/P/sub 5/

Description: The zero-field muon spin relaxation function G/sub zz/(t) has been measured as a function of reduced temperature t = T/T/sug g/ in the amorphous metallic spin glasses Pd/sub 75/Fe/sub 5/Si/sub 20/ and Pd/sub 75/Fe/sub 5/P/sub 20/. The results are in qualitative agreement with earlier measurements on dilute alloy spin glasses, including an onset of static order below T/sub g/ and a (t/(t - 1))/sup 2/ dependence of the correlation time tau/sub c/ above T/sub g/. Both samples have the same tau/sub… more
Date: January 1, 1986
Creator: Brewer, J. H.; Spencer, D. P.; Huang, C. Y.; Uemura, Y. J. & Chen, H. S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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First-principles calculations: The elemental transition metals and their compounds

Description: If done with sufficient care, present day a priori theory yields calculated enthalpies of formation whose agreement with experiment (when such data is available) is of the order of the experimental scatter. Comparisons will be made for the Pt-Ti systems for which such data exist and for which one crystal structure involves atomics sites of low symmetry. Two other cases will be considered for which there is no direct experimental heats data. The first of these will be the structural stabilities … more
Date: January 1, 1991
Creator: Watson, R. E.; Fernando, G. W.; Weinert, M. & Davenport, J. W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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High-temperature thermodynamic activities of zirconium in platinum alloys determined by nitrogen-nitride equilibria

Description: A high-temperature nitrogen-nitride equilibrium apparatus is constructed for the study of alloy thermodynamics to 2300/sup 0/C. Zirconium-platinum alloys are studied by means of the reaction 9ZrN + 11Pt ..-->.. Zr/sub 9/Pt/sub 11/ + 9/2 N/sub 2/. Carful attention is paid to the problems of diffusion-limited reaction and ternary phase formation. The results of this study are and a/sub Zr//sup 1985/sup 0/C/ = 2.4 x 10/sup -4/ in Zr/sub 9/Pt/sub 11/ ..delta..G/sub f 1985/sup 0/C//sup 0/ Zr/sub 9/P… more
Date: May 1, 1980
Creator: Goodman, D.A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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High-power laser and arc welding of thorium-doped iridium alloys

Description: The arc and laser weldabilities of two Ir-0.3% W alloys containing 60 and 200 wt ppM Th have been investigated. The Ir-.03% W alloy containing 200 wt ppM Th is severely prone to hot cracking during gas tungsten-arc welding. Weld metal cracking results from the combined effects of heat-affected zone liquation cracking and solidification cracking. Scanning electron microscopic analysis of the fractured surface revealed patches of low-melting eutectic. The cracking is influenced to a great extent … more
Date: May 1, 1980
Creator: David, S.A. & Liu, C.T.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Catalysis at experimentally designed surfaces: n-Butane hydrogenolysis at Sn/Group VIII surface alloys

Description: Bimetallic {radical}3x{radical}3R30{degrees}-Sn/M(111) (M=Ni, Pt) surface alloys have been prepared in an ultrahigh vacuum system and used in model moderate pressure (1--200 Torr) catalytic reactions. Hydrogenolysis of n-butane (H{sub 2}/n-C4=20) has been used to characterize the effects of ordered bimetallic ensembles relative to those available at the respective (111) surfaces. The effect of alloying Sn into the Ni(111) surface produced an overall lowering of the catalytic reactivity nearly e… more
Date: January 1, 1992
Creator: Logan, A. D. & Paffett, M. T.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Microstructure and hydriding studies of AB/sub 5/ hydrogen storage compounds. Final report

Description: New data on the microstructure, pressure-composition-temperature, and absorption/desorption kinetics of AB/sub 5/ metal hydrides are presented. The most significant result to emerge from the investigation is that many of the AB/sub 5/ metal hydrides, especially the LaNi/sub 5/ related materials, show instantaneous absorption and desorption response in proportion to the amount of cooling or heating which is provided. Eight categories of materials were studied: reference alloys (LaNi/sub 5/, LaNi… more
Date: January 1, 1980
Creator: Goodell, P. D.; Sandrock, G. D. & Huston, E. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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High-temperature compatibility study of iridium (DOP-26 alloy) with graphite and plutonia

Description: This report outlines the materials compatibility tests conducted on DOP-26 iridium alloy and carbon. The carbon used was in the form of woven graphite as present in the impact shell used to encase plutonia in nuclear heat sources. In addition, compatibility tests of the DOP-26 alloy with plutonia are described. The reactivity observed in both systems is discussed. 4 refs., 6 figs.
Date: December 1, 1987
Creator: Axler, K.M. & Eash, D.T.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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