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in subjects: "Phase Diagrams"

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

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: Report

Partner: UNT Libraries Government Documents Department

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Some Scoping Experiments for a Space Reactor

Some scoping experiments were performed to evaluate fuel performance in a lithium heat pipe reactor operating at a nominal 1500K heat pipe temperature. Fuel-coolant and fuel-coolant-clad relationships showed that once a failed heat pipe occurs temperatures can rise high enough so that large concentrations of uranium can be transported by the vapor phase. Upon condensation this uranium would be capable of penetrating heat pipes adjacent to the failed pipe. The potential for propagation of failur… more

Date: July 7, 1983

Creator: Alexander, C. A. & Ogden, J. S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Uranium hexafluoride: Safe handling, processing, and transporting: Conference proceedings

This conference seeks to provide a forum for the exchange of information and ideas of the safety aspects and technical issue related to the handling of uranium hexafluoride. By allowing operators, engineers, scientists, managers, educators, and others to meet and share experiences of mutual concern, the conference is also intended to provide the participants with a more complete knowledge of technical and operational issues. The topics for the papers in the proceedings are widely varied and inc… more

Date: January 1, 1988

Creator: Strunk, W.D. & Thornton, S.G. (eds.)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Existence of fcc TiCr/sub 1/ /sub 8/H/sub 5/ /sub 3/

Originally an orthorhombic structure was assigned to the non-stoichiometric hydride TiCr/sub 1/ /sub 8/H/sub 3/ /sub 6/. Recent neutron and x-ray diffraction data indicated, however, that an alternate interpretation was possible, i.e. the solid consists of two hydride phases, an ..cap alpha..' Laves phase having a composition of TiCr/sub 1/ /sub 8/H/sub 2/ /sub 8/ and an fcc phase with a much higher hydrogen content. This proved to be the case and it has been determined that the high concentrat… more

Date: February 1, 1982

Creator: Johnson, J. R.; Reilly, J. J.; Reidinger, F.; Corliss, L. M. & Hastings, J. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Synchrotron x-ray study of physisorbed films of mixtures of Ar and Xe on graphite

Mixtures of Ar and Xe have been studied in most of the submonolayer region of the phase diagram (T,chi,rho), T = temperature, chi = chemical composition, rho = fraction of a monolayer. The basic feature is a large tendency to form ..sqrt.. 3 x ..sqrt.. 3 commensurate alloys (Kr-like structures), but none of the commensurate nor of the incommensurate structures form a chemically ordered alloy at 11 K. Thus the 2D solid can be thought of as a solid consisting of particles of an average size. This… more

Date: July 1, 1982

Creator: Bohr, J.; Nielsen, M.; McTague, J. P.; Als-Nielsen, J. & Kjaer, K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Advances in materials science, Metals and Ceramics Division. Triannual progress report, February-May 1980

Research is reported in the magnetic fusion energy and laser fusion energy programs, aluminium-air battery and vehicle research, geothermal research, nuclear waste management, basic energy science, and chemistry and materials science. (FS)

Date: August 1, 1980

Creator: Truhan, J.J. & Gordon, K.M. (eds.)

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Phase Transformations in Alumina. Technical Report, May to December 1961

e transformation studies showed that synthetic aluminas produced in the laboratory were not transformed to alpha alumina at 400 to 700' deg n the presence of nitric acid and water vapor. Amorphous aluminn produced in the pilot plant was transformed to alpha alumina. This indicated that the amorphous alumina produced in the pilot plant is structurally predisposed to form alpha alumina. Most additives did not appear to have any special effects. Lithium formed zeta alumina, LiAl/sub 5/O/sub 8/. Ph… more

Date: December 1, 1961

Creator: Eding, H J; Huggins, M L & Brown, A G

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Preparation and some properties of Cu-Li alloys containing up to 20 at. % Li

Lithium strongly segregates to the surface of Cu-Li alloys, thus substantially lowering the Cu sputtering yield relative to pure Cu. Use of Cu-Li limiters or divertors in tokamaks can therefore be expected to be beneficial in limiting high-Z plasma impurity influx. A large scale (100-200g) method for the preparation of Cu-Li alloys is described. Analysis reveals that on solidification from the melt stratification occurs which leads to compositional inhomogeneity. The results are discussed in th… more

Date: January 1, 1985

Creator: Mendelsohn, M.; Krauss, A. R. & Gruen, D. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Glass forming ranges of amorphous alloys

Two main methods of synthesis of amorphous metallic alloys are based on the rapid solidification of molten alloys and on isothermal solid state reactions between pure metals. We discuss recent calculations for the glass forming range for both techniques and we compare the predicted homogeneity ranges of the amorphous phase with experiments. 10 refs., 2 figs.

Date: January 1, 1988

Creator: Schwarz, R.B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Energetics and statistics of order in alloys with application to oxide superconductors

Now that first-principles calculations of ordering transformations are becoming increasingly accurate, the deficiencies of earlier mean field methods are becoming increasingly apparent. New techniques, based on cluster expansions, are now alleviating many of the earlier problems and are producing very satisfactory results. These ideas will be illustrated for the case of oxygen ordering in the YBa{sub 2}Cu{sub 3}O{sub z} superconducting compound, for which a very simple two-dimensional Ising mod… more

Date: June 1, 1991

Creator: de Fontaine, D. (Lawrence Livermore National Lab., CA (United States) California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering); Ceder, G. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering) & Asta, M. (Lawrence Livermore National Lab., CA (United States) California Univ., Berkeley, CA (United States).

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Analyses and predictions of the thermodynamic properties and phase diagrams of silicate systems

Molten silicates are ordered solutions which can not be well represented by the usual polynomial representation of deviations from ideal solution behavior (i.e. excess free energies of mixing). An adaptation of quasichemical theory which is capable of describing the properties of ordered solutions represents the measured properties of binary silicates over broad ranges of composition and temperature. For simple silicates such as the MgO-FeO-SiO{sub 2} ternary system, in which silica is the only… more

Date: January 1, 1992

Creator: Blander, M. (Argonne National Lab., IL (United States)); Pelton, A. & Eriksson, G. (Ecole Polytechnique, Montreal, PQ (Canada). Dept. of Metallurgy and Materials Engineering)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Heat pump augmented radiator for low-temperature space applications

Closed-cycle, space-based heat rejection systems depend solely on radiation to achieve their heat dissipation function. Since the payload heat rejection temperature is typically 50 K above that of the radiation sink in near earth orbit, the size and mass of these systems can be appreciable. Size (and potentially mass) reductions are achievable by increasing the rejection temperature via a heat pump. Two heat pump concept were examined to determine if radiator area reductions could be realized w… more

Date: January 1, 1988

Creator: Olszewski, M. & Rockenfeller, U.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Hot corrosivity of coal gasification products on gas turbine alloys. Summary report, 15 April 1978-15 November 1979

The results of this investigation have produced mechanisms for the hot corrosion of a number of pure metals and alloys in the types of atmospheres likely to be obtained in turbines using coal conversion products as fuel. The results of these mechanistic studies suggest the following conclusions regarding application of alloys in these situations: (1) Simple Cr/sub 2/O/sub 3/-forming alloys of both Co and Ni have good hot corrosion resistance to most of the deposits likely to form in turbines bu… more

Date: January 1, 1979

Creator: Meier, G.H. & Gulbransen, E.A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Thermal energy storage technical progress report, April 1990--March 1991

The Department of Energy (DOE) is supporting development of thermal energy storage (TES) as a means of efficiently coupling energy supplies to variable heating or cooling demands. Uses of TES include electrical demand-side management in buildings and industry, extending the utilization of renewable energy resources such as solar, and recovery of waste heat from periodic industrial processes. Technical progress to develop TES for specific diurnal and industrial applications under Oak Ridge Natio… more

Date: March 1, 1992

Creator: Tomlinson, J.J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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The EDM surface: Topography, chemistry, and metallurgy

The surface created by the electric discharge machining (EDM) process is of special interest because it has been shown to have a negative effect on the fatigue properties of many alloys. An understanding of the surface metallurgy and chemistry is important in predicting those alloys which are most susceptible to failure. Remedial actions, including thickness minimization, alteration, or removal of the surface layer are addressed.

Date: January 1, 1991

Creator: Fuller, J.E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Momentum-dependent mean field and the nuclear equation of state

We study the momentum distribution of nucleons in nuclear matter and calculate the incompressibility analytically in the presence of a momentum-dependent mean field. An equivalent mass is introduced for calculational purposes. The effect of the momentum-dependence of the mean field on the hadronic equation of state is examined and the conditions for equilibrium with a quark phase described by a bag model equation of state are investigated. 12 refs., 4 figs.

Date: 1991-01~

Creator: Csernai, László P.; Fai, George; Gale, Charles & Osnes, Eivind

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Simple method for the calculation and use of CVD phase diagrams with applications to the Ti-B-Cl-H system, 1200 to 800/sup 0/K

A simple method for calculating multi-component gas-solid equilibrium phase diagrams for chemical vapor deposition (CVD) systems is presented. The method proceeds in three steps: dtermination of stable solid assemblages, evaluation of gas-solid stability relations, and calcuation of conventional phase diagrams using a new free energy minimization technique. The phase diagrams can be used to determine (1) bulk compositions and phase fields accessible by CVD techniques; (2) expected condensed pha… more

Date: March 1, 1980

Creator: Randich, E. & Gerlach, T. M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Applications of pulsed neutron powder diffraction to actinide elements. [Pu-Al]

We have been using the technique of pulsed neutron powder diffraction to study several problems in the physics and chemistry of the actinide elements. In these elements one often encounters very complex structures resulting from polymorphic transformations presumably induced by the presence of 5f-electrons. For example, at least five distinct structures of plutonium metal are found between room temperature and its melting point of 640/sup 0/C, and two of the structures are monoclinc. The determ… more

Date: November 1, 1987

Creator: Lawson, A. C.; Richardson, J. W.; Mueller, M. H.; Lander, G. H.; Goldstone, J. A.; Williams, A. et al.

Item Type: Article

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

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: Article

Partner: UNT Libraries Government Documents Department

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Computer simulation at high pressure

The use of either the Monte Carlo or molecular dynamics method to generate equations-of-state data for various materials at high pressure is discussed. Particular emphasis is given to phase diagrams, such as the generation of various types of critical lines for mixtures, melting, structural and electronic transitions in solids, two-phase ionic fluid systems of astrophysical interest, as well as a brief aside of possible eutectic behavior in the interior of the earth. Then the application of the… more

Date: November 1, 1977

Creator: Alder, B. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Theory of alloy phases

Various non-thermodynamic approaches to understanding and predicting phase diagrams are explored from the viewpoint of solid-state physics. The review is intended to indicate the scope of activity and some of the progress which has been made. (GHT)

Date: January 1, 1977

Creator: Watson, R. E.; Ehrenreich, H. & Bennett, L. H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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MHD electrode development. Quarterly report, April-June 30, 1980

Emphasis within this program is now being directed towards the engineering development of cold metallic electrodes, and in particular the identification and evaluation of alternatives to platinum for use as anodes. A literature search, concentrating on hot corrosion resistant alloys, has been undertaken and results are presented. In addition, results of platinum-copper diffusion studies and a preliminary evaluation of sputter coated specimens of TiB/sub 2/ clad copper are reported. Laboratory a… more

Date: August 1, 1980

Creator: Sadler, J W; Dietrick, D L & Frantti, E W

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Application of artificial intelligence control to the vapor-liquid-solid silicon carbide whisker process

Silicon carbide whiskers have excellent mechanical and chemical properties, making them very desirable as a reinforcement for structural ceramic and other composite materials. Los Alamos has developed a laboratory-scale batch process for producing very high quality SiC whiskers by the vapor-liquid-solid (VLS) method which is an active candidate for technology transfer involving significant scale-up. The process, however, involves quite complex chemical/physical and parametric relationships and … more

Date: January 1, 1989

Creator: Shalek, P.D. & Parkinson, W.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Statics and kinetics of oxygen ordering in the oxide superconductor YBa sub 2 Cu sub 3 O sub z

Oxygen ordering in the high-temperature superconductor YBa{sub 2}Cu{sub 3}O{sub z} is well described by a two-dimensional Ising model with anisotropic next-nearest neighbor effective pair interactions, repulsive along the a direction, attractive along b. Monte Carlo simulation shows that this marked anisotropy gives rise, particularly at stoichiometric index z close to 7, to large deviations from unity of the ratio D{sub 11}{sup *}/D{sub 22}{sup *} of tracer diffusion tensor components in the a… more

Date: March 1, 1992

Creator: McCormack, R.; de Fontaine, D. (Lawrence Berkeley Lab., CA (United States)); Ceder, G. (Massachusetts Inst. of Tech., Cambridge, MA (United States)) & Salomons, E. (CEN Saclay, Gif-sur-Yvette, (France))

Item Type: Article

Partner: UNT Libraries Government Documents Department