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Sample records for v-h solid-solution alloys

  1. Solid solution lithium alloy cermet anodes

    Science.gov (United States)

    Richardson, Thomas J.

    2013-07-09

    A metal-ceramic composite ("cermet") has been produced by a chemical reaction between a lithium compound and another metal. The cermet has advantageous physical properties, high surface area relative to lithium metal or its alloys, and is easily formed into a desired shape. An example is the formation of a lithium-magnesium nitride cermet by reaction of lithium nitride with magnesium. The reaction results in magnesium nitride grains coated with a layer of lithium. The nitride is inert when used in a battery. It supports the metal in a high surface area form, while stabilizing the electrode with respect to dendrite formation. By using an excess of magnesium metal in the reaction process, a cermet of magnesium nitride is produced, coated with a lithium-magnesium alloy of any desired composition. This alloy inhibits dendrite formation by causing lithium deposited on its surface to diffuse under a chemical potential into the bulk of the alloy.

  2. Atomistic Simulations of Dislocations in a Model BCC Multicomponent Concentrated Solid Solution Alloy (Postprint)

    Science.gov (United States)

    2016-12-19

    Dislocations ; Atomistic simulations; Concentrated multicomponent solid solution alloy; BCC crystal 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...This has implications for higher-scale modeling ( dislocation dynamics or crystal plasticity) of HEA alloys, relative to elemental BCC metals, which...AFRL-RX-WP-JA-2017-0302 ATOMISTIC SIMULATIONS OF DISLOCATIONS IN A MODEL BCC MULTICOMPONENT CONCENTRATED SOLID SOLUTION ALLOY

  3. Local Structure and Short-Range Order in a NiCoCr Solid Solution Alloy

    Science.gov (United States)

    Zhang, F. X.; Zhao, Shijun; Jin, Ke; Xue, H.; Velisa, G.; Bei, H.; Huang, R.; Ko, J. Y. P.; Pagan, D. C.; Neuefeind, J. C.; Weber, W. J.; Zhang, Yanwen

    2017-05-01

    Multielement solid solution alloys are intrinsically disordered on the atomic scale, and many of their advanced properties originate from the local structural characteristics. The local structure of a NiCoCr solid solution alloy is measured with x-ray or neutron total scattering and extended x-ray absorption fine structure (EXAFS) techniques. The atomic pair distribution function analysis does not exhibit an observable structural distortion. However, an EXAFS analysis suggests that the Cr atoms are favorably bonded with Ni and Co in the solid solution alloys. This short-range order (SRO) may make an important contribution to the low values of the electrical and thermal conductivities of the Cr-alloyed solid solutions. In addition, an EXAFS analysis of Ni ion irradiated samples reveals that the degree of SRO in NiCoCr alloys is enhanced after irradiation.

  4. Fabrication of nanocrystalline alloys Cu–Cr–Mo super satured solid solution by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar, C., E-mail: claudio.aguilar@usm.cl [Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Guzmán, D. [Departamento de Ingeniería en Metalurgia, Facultad de Ingeniería, Universidad de Atacama y Centro Regional de Investigación y Desarrollo Sustentable de Atacama (CRIDESAT), Av. Copayapu 485, Copiapó (Chile); Castro, F.; Martínez, V.; Cuevas, F. de las [Centro de Estudios e Investigaciones Técnicas de Gipuzkoa, Paseo de Manuel Lardizábal, N° 15, 20018 San Sebastián (Spain); Lascano, S. [Departamento de Ingeniería Mecánica, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Muthiah, T. [Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile)

    2014-08-01

    This work discusses the extension of solid solubility of Cr and Mo in Cu processed by mechanical alloying. Three alloys processed, Cu–5Cr–5Mo, Cu–10Cr–10Mo and Cu–15Cr–15Mo (weight%) using a SPEX mill. Gibbs free energy of mixing values 10, 15 and 20 kJ mol{sup −1} were calculated for these three alloys respectively by using the Miedema's model. The crystallite size decreases and dislocation density increases when the milling time increases, so Gibbs free energy storage in powders increases by the presence of crystalline defects. The energy produced by crystallite boundaries and strain dislocations were estimated and compared with Gibbs free energy of mixing values. The energy storage values by the presence of crystalline defects were higher than Gibbs free energy of mixing at 120 h for Cu–5Cr–5Mo, 130 h for Cu–10Cr–10Mo and 150 h for Cu–15Cr–15Mo. During milling, crystalline defects are produced that increases the Gibbs free energy storage and thus the Gibbs free energy curves are moved upwards and hence the solubility limit changes. Therefore, the three alloys form solid solutions after these milling time, which are supported with the XRD results. - Highlights: • Extension of solid solution Cr and Mo in Cu achieved by mechanical alloying. • X-ray characterization of Cu–Cr–Mo system processed by mechanical alloying. • Thermodynamics analysis of formation of solid solution of the Cu–Cr–Mo system.

  5. Solid Solution Effects on the Tensile Behaviour of Concentrated Mg-Zn Alloys

    Science.gov (United States)

    Blake, A. H.; Cáceres, C. H.

    Solute in solution hardens the basal planes but causes solid solution softening on the prismatic (and possibly pyramidal) planes in dilute (slip systems still occurs. Therefore, solid solution effects on the strain hardening rate and ductility of cast polycrystalline Mg-Zn alloys, with Zn contents between 0 and 2.4 at.% have been studied. A constant grain size was obtained in all alloys by adding a small amount of Zr to the melt. The strain-hardening rate is low for dilute concentrations increasing monotonically above 1 at.% Zn. The ductility goes through a maximum at very low concentrations of Zn, decreasing for higher concentrations. This suggests that the solid solution hardening gradually offsets the solid solution softening effects at high concentrations of Zn.

  6. Structural study of nanocrystalline solid solution of Cu-Mo obtained by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar, C., E-mail: claudio.aguilar@usm.cl [Departamento de Ingenieria Metalurgica y de Materiales, Universidad Tecnica Federico Santa Maria, Avenida Espana 1680, Valparaiso (Chile); Instituto de Materiales y Procesos Termomecanicos, Universidad Austral de Chile, General Lagos 2086, Valdivia (Chile); Castro, F. [Centro de Estudios e Investigaciones Tecnicas de Gipuzkoa, Paseo de Manuel Lardizabal, N Degree-Sign 15 20018, San Sebastian (Spain); Martinez, V. [TEKMETALL, Metallurgical Solutions S.L., Paseo neinor, Iribar Kalea 5, F1. B. de Igara 20018, San Sebastian (Spain); Guzman, D. [Departamento de Ingenieria en Metalurgia, Facultad de Ingenieria, Universidad de Atacama y Centro Regional de Investigacion y Desarrollo Sustentable de Atacama (CRIDESAT), Av. Copayapu 485, Copiapo (Chile); Cuevas, F. de las; Lozada, L.; Vielma, N. [Centro de Estudios e Investigaciones Tecnicas de Gipuzkoa, Paseo de Manuel Lardizabal, N Degree-Sign 15 20018, San Sebastian (Spain)

    2012-06-30

    Highlights: Black-Right-Pointing-Pointer Extension of solid solution in Cu-Mo system achieved by mechanical alloying. Black-Right-Pointing-Pointer X-ray characterization of Cu-Mo system processed by mechanical alloying. Black-Right-Pointing-Pointer Structural study of nanocrystalline solid solution of Cu-Mo obtained by mechanical alloying. - Abstract: This work studied the structural evolution of Cu-xMo (x = 5 and 8 wt.%) alloys processed by mechanical alloying using x-ray diffraction profiles, scanning electron microscopy, differential scanning calorimetric and microhardness. X-ray diffraction analysis was done using the modified Williamson-Hall and Warren-Averbach methods. These were used to determine structural properties, such as crystallite size, stacking fault probability and energy, dislocation density of metallic powder as a function of the amount of Mo and milling time. The main results obtained for both alloys were higher dislocation density and Vickers microhardness values were measured and crystallites sizes of around 10 nm were measured for both systems at 50 h of milling. Lattice defects increase the free energy and the free energy curves shift upwards, therefore the solubility limits change and Cu-Mo solid solution is formed.

  7. Studying the Super-cooled Solid Solution Breakdown of V-1341 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Yu. A. Puchkov

    2017-01-01

    Full Text Available Deformable alloys of the Al-Mg-Si system are widely used in aviation industry, rocket engineering, shipbuilding, as well as on railway and highway transport. These alloys are characterized by high stamping ability, weld-ability, and machinability with a comparatively high strength and corrosion resistance in a heat-strengthened state. A promising alloy of the Al-Mg-Si system with increased structural strength and manufacturability is on par with foreign analogues in properties is the V-1341 alloy [1, 2].The properties of heat-treatable aluminum alloys strongly depend on the cooling rate of the product during quenching [3-12], which determines the structure and level of residual stresses. Decrease in structural strength, tendency to pitting and inter-crystalline corrosion with slow cooling from the quenching temperature is caused by formation of coarse unequiaxed precipitate, precipitates-free zones, and also by decreasing proportion of inclusions of the strengthening phase [3-12].Thus, the relevant task is to study the effect of isothermal quenching modes on the structure of deformable V-1341 aluminum alloy thermally hardened.The paper studies the impact of isothermal time in quenching on the composition and morphology of breakdown products of the V-1341 alloy solid solution. It is shown that at isothermal time under the solid solution breakdown, at first on the dispersoid surface and then in the solid solution are formed and grow large needle-like crystals of the β'-phase which are structural concentrators of stresses. An increasing isothermal time leads to decreasing solid solution super-saturation by doping elements and vacancies. This leads to a decrease in the fraction of the coherent finely dispersed hardening β '' phase, and also to an increase in the width of the precipitates-free zone.

  8. Contribution of Lattice Distortion to Solid Solution Strengthening in a Series of Refractory High Entropy Alloys

    Science.gov (United States)

    Chen, H.; Kauffmann, A.; Laube, S.; Choi, I.-C.; Schwaiger, R.; Huang, Y.; Lichtenberg, K.; Müller, F.; Gorr, B.; Christ, H.-J.; Heilmaier, M.

    2017-11-01

    We present an experimental approach for revealing the impact of lattice distortion on solid solution strengthening in a series of body-centered-cubic (bcc) Al-containing, refractory high entropy alloys (HEAs) from the Nb-Mo-Cr-Ti-Al system. By systematically varying the Nb and Cr content, a wide range of atomic size difference as a common measure for the lattice distortion was obtained. Single-phase, bcc solid solutions were achieved by arc melting and homogenization as well as verified by means of scanning electron microscopy and X-ray diffraction. The atomic radii of the alloying elements for determination of atomic size difference were recalculated on the basis of the mean atomic radii in and the chemical compositions of the solid solutions. Microhardness (μH) at room temperature correlates well with the deduced atomic size difference. Nevertheless, the mechanisms of microscopic slip lead to pronounced temperature dependence of mechanical strength. In order to account for this particular feature, we present a combined approach, using μH, nanoindentation, and compression tests. The athermal proportion to the yield stress of the investigated equimolar alloys is revealed. These parameters support the universality of this aforementioned correlation. Hence, the pertinence of lattice distortion for solid solution strengthening in bcc HEAs is proven.

  9. Multi-component solid solution alloys having high mixing entropy

    Science.gov (United States)

    Bei, Hongbin

    2015-10-06

    A multi-component high-entropy alloy includes a composition selected from the following group: VNbTaTiMoWRe, VNbTaTiMoW, VNbTaTiMoRe, VNbTaTiWRe, VNbTaMoWRe, VNbTiMoWRe, VTaTiMoWRe, NbTaTiMoWRe, VNbTaTiMo, VNbTaTiW, VNbTaMoW, VNbTiMoW, VTaTiMoW, NbTaTiMoW, VNbTaTiRe, VNbTaMoRe, VNbTiMoRe, VTaTiMoRe, NbTaTiMoRe, VNbTaWRe, VNbTiWRe, VTaTiWRe, NbTaTiWRe, VNbMoWRe, VTaMoWRe, NbTaMoWRe, VTiMoWRe, NbTiMoWRe, TaTiMoWRe, wherein relative amounts of each element vary by no more than .+-.15 atomic %.

  10. Influence of chemical disorder on energy dissipation and defect evolution in concentrated solid solution alloys

    Science.gov (United States)

    Zhang, Yanwen; Stocks, G. Malcolm; Jin, Ke; Lu, Chenyang; Bei, Hongbin; Sales, Brian C.; Wang, Lumin; Béland, Laurent K.; Stoller, Roger E.; Samolyuk, German D.; Caro, Magdalena; Caro, Alfredo; Weber, William J.

    2015-01-01

    A grand challenge in materials research is to understand complex electronic correlation and non-equilibrium atomic interactions, and how such intrinsic properties and dynamic processes affect energy transfer and defect evolution in irradiated materials. Here we report that chemical disorder, with an increasing number of principal elements and/or altered concentrations of specific elements, in single-phase concentrated solid solution alloys can lead to substantial reduction in electron mean free path and orders of magnitude decrease in electrical and thermal conductivity. The subsequently slow energy dissipation affects defect dynamics at the early stages, and consequentially may result in less deleterious defects. Suppressed damage accumulation with increasing chemical disorder from pure nickel to binary and to more complex quaternary solid solutions is observed. Understanding and controlling energy dissipation and defect dynamics by altering alloy complexity may pave the way for new design principles of radiation-tolerant structural alloys for energy applications. PMID:26507943

  11. Solid solution and amorphous phase in Ti–Nb–Ta–Mn systems synthesized by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar, C., E-mail: claudio.aguilar@usm.cl [Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Guzman, P. [Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Lascano, S. [Departamento de Ingeniería Mecánica, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Parra, C. [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Bejar, L. [Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, Morelia C.P. 58000, Michoacán (Mexico); Medina, A. [Facultad de Ingeniería Mecánica, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, C.P. 58000, Michoacán (Mexico); Guzman, D. [Departamento de Metalurgia, Universidad de Atacama, Av. España 485, Copiapó (Chile)

    2016-06-15

    This work discusses the formation of Ti–30Nb–13Ta–xMn (x: 2, 4 and 6 wt%) solid solution by mechanical alloying using a shaker mill. A solid solution was formed after 15 h of milling and an amorphous phase was formed after 30 h of milling, according to X-ray diffraction results. Disappearance of strongest X-ray diffraction peaks of Nb, Ta and Mn indicated the formation of solid solution, while, X-ray diffraction patterns of powders milled for 30 h showed an amorphous hump with crystalline peaks in the angular range of 35–45° in 2θ. TEM image analysis showed the presence of nanocrystalline intermetallic compounds embedded in an amorphous matrix. Mn{sub 2}Ti, MnTi and NbTi{sub 4} intermetallic compounds were detected and revealed crystallites with size ranging from 3 to 20 nm. The Gibbs free energy for the formation of solid solution and amorphous phase of three ternary systems (Ti–Nb–Ta, Ti–Nb–Mn and Ti–Ta–Mn) was calculated using extended Miedema's model. Experimental and thermodynamic data confirmed that solid solution was first formed in the alloy with 6wt% Mn followed by the formation of an amorphous phase as milling time increases. The presence of Mn promoted the formation of amorphous phase because the atomic radius difference between Mn with Ti, Nb and Ta. - Highlights: • Thermodynamics analysis of extension of solid solution of the Ti–Nb–Ta–Mn system. • Formation of amorphous phase and intermetallic compounds were observed. • Nanocrystalline intermetallic compounds were formed with the sizes between 3 and 20 nm.

  12. Al-Fe solid solutions in alloys obtained by melt spinning

    Energy Technology Data Exchange (ETDEWEB)

    Badan, B.; Magrini, M.; Zambon, A. [Univ. di Padova (Italy). Dept. of Mechanical and Management Innovation

    1996-07-01

    The extension of solid solutions is one of the more claimed effects of solidification under high cooling rates. The possibility to increase, by such technology, the extremely small amount (0,006 at% at 500 C) of iron in aluminum was extensively studied and recently received further attention, owing to the interesting technological properties of Al-Fe alloys. However the rapid quenching from the liquid not only affects the amount of iron retained in solid solution, but also the possible formation of other intermetallic phases, and, more generally, the location of iron atoms retained in the metastable solid solution of aluminum. Different situations of iron atoms have been investigated using XRD, TEM and Moessbauer spectroscopy (MS), but from the interpretation of the results some problems to obtain unambiguous conclusions arise. In any case it seems interesting to clarify the actual extension of solubility of iron in aluminum, in rather concentrated alloys, in which the formation of metastable intermetallic compounds cannot be suppressed. The paper reports MS analysis of Al-Fe (0,1--4 at%) alloys, rapidly solidified by melt spinning.

  13. Simple thermodynamic model of the extension of solid solution of Cu-Mo alloys processed by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar, C., E-mail: claudio.aguilar@usm.cl [Departamento de Ingenieria Metalurgica y de Materiales, Universidad Tecnica Federico Santa Maria, Avenida Espana 1680, Valparaiso (Chile); Guzman, D. [Departamento de Metalurgia, Facultad de Ingenieria, Universidad de Atacama, Av. Copayapu 485, Copiapo (Chile); Rojas, P.A. [Escuela de Ingenieria Mecanica, Facultad de Ingenieria, Pontificia Universidad Catolica de Valparaiso, Av. Los Carrera 01567, Quilpue (Chile); Ordonez, Stella [Departamento de Ingenieria Metalurgica, Facultad de Ingenieria, Universidad de Santiago de Chile, Av. L. Bernardo O' Higgins 3363, Santiago (Chile); Rios, R. [Instituto de Materiales y Procesos Termomecanicos, Facultad de Ciencias de la Ingenieria, Universidad Austral de Chile, General Lagos 2086, Valdivia (Chile)

    2011-08-15

    Highlights: {yields} Extension of solid solution in Cu-Mo systems achieved by mechanical alloying. {yields} Simple thermodynamic model to explain extension of solid solution of Mo in Cu. {yields} Model gives results that are consistent with the solubility limit extension reported in other works. - Abstract: The objective of this work is proposing a simple thermodynamic model to explain the increase in the solubility limit of the powders of the Cu-Mo systems or other binary systems processed by mechanical alloying. In the regular solution model, the effects of crystalline defects, such as; dislocations and grain boundary produced during milling were introduced. The model gives results that are consistent with the solubility limit extension reported in other works for the Cu-Cr, Cu-Nb and Cu-Fe systems processed by mechanical alloying.

  14. A New Thermodynamic Parameter to Predict Formation of Solid Solution or Intermetallic Phases in High Entropy Alloys (Postprint)

    Science.gov (United States)

    2015-11-02

    AFRL-RX-WP-JA-2016-0345 A NEW THERMODYNAMIC PARAMETER TO PREDICT FORMATION OF SOLID SOLUTION OR INTERMETALLIC PHASES IN HIGH ENTROPY...Interim 22 September 2014 – 21 September 2015 4. TITLE AND SUBTITLE A NEW THERMODYNAMIC PARAMETER TO PREDICT FORMATION OF SOLID SOLUTION OR...simple thermodynamic criterion is proposed to predict the presence or absence of equilibrium intermetallic phases in a high entropy alloy at a given

  15. Inelasticity and precipitation of germanium from a solid solution in Al-Ge binary alloys

    Science.gov (United States)

    Kardashev, B. K.; Korchunov, B. N.; Nikanorov, S. P.; Osipov, V. N.

    2015-08-01

    The influence of precipitation of germanium atoms in a solid solution on the dependence of the inelasticity characteristics on the germanium content in aluminum-germanium alloys prepared by directional crystallization has been studied. It has been shown that the Young's modulus defect, the amplitude-dependent decrement, and the microplastic flow stress at a specified cyclic strain amplitude have extreme values at the eutectic germanium content in the alloy. The eutectic composition of the alloy undergoes a ductilebrittle transition. It has been found that there is a correlation between the dependences of the Young's modulus defect, amplitude-dependent decrement, microplastic flow stress, and specific entropy of the exothermal process of germanium precipitation on the germanium content in the hypoeutectic alloy. The concentration dependences of the inelasticity characteristics and their changes after annealing have been explained by the change in the resistance to the motion of intragrain dislocations due to different structures of the Guinier-Preston zones formed during the precipitation of germanium atoms.

  16. Unique Challenges for Modeling Defect Dynamics in Concentrated Solid-Solution Alloys

    Science.gov (United States)

    Zhao, Shijun; Weber, William J.; Zhang, Yanwen

    2017-11-01

    Recently developed concentrated solid solution alloys (CSAs) are shown to have improved performance under irradiation that depends strongly on the number of alloying elements, alloying species, and their concentrations. In contrast to conventional dilute alloys, CSAs are composed of multiple principal elements situated randomly in a simple crystalline lattice. As a result, the intrinsic disorder has a profound influence on energy dissipation pathways and defect evolution when these CSAs are subjected to energetic particle irradiation. Extraordinary irradiation resistance, including suppression of void formation by two orders of magnitude at an elevated temperature, has been achieved with increasing compositional complexity in CSAs. Unfortunately, the loss of translational invariance associated with the intrinsic chemical disorder poses great challenges to theoretical modeling at the electronic and atomic levels. Based on recent computer simulation results for a set of novel Ni-containing, face-centered cubic CSAs, we review theoretical modeling progress in handling disorder in CSAs and underscore the impact of disorder on defect dynamics. We emphasize in particular the unique challenges associated with the description of defect dynamics in CSAs.

  17. Stacking fault energy measurements in solid solution strengthened Ni-Cr-Fe alloys using synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Unfried-Silgado, Jimy [Metals Characterization and Processing Laboratory, Brazilian Nanothecnology National Laboratory - CNPEM/ABTLuS, Caixa Postal 6192, CEP 13083-970, Campinas, Sao Paulo (Brazil); Universidade Estadual de Campinas UNICAMP, Faculdade de Engenharia Mecanica FEM, Campinas (Brazil); Universidad Autonoma del Caribe, Grupo IMTEF, Ingenieria Mecanica, Barranquilla (Colombia); Wu, Leonardo [Metals Characterization and Processing Laboratory, Brazilian Nanothecnology National Laboratory - CNPEM/ABTLuS, Caixa Postal 6192, CEP 13083-970, Campinas, Sao Paulo (Brazil); Furlan Ferreira, Fabio [Universidade Federal do ABC, Centro de Ciencias Naturais e Humanas (CCNH), Sao Paulo (Brazil); Mario Garzon, Carlos [Universidad Nacional de Colombia, Departamento de Fisica, Bogota (Colombia); Ramirez, Antonio J, E-mail: antonio.ramirez@lnnano.org.br [Metals Characterization and Processing Laboratory, Brazilian Nanothecnology National Laboratory - CNPEM/ABTLuS, Caixa Postal 6192, CEP 13083-970, Campinas, Sao Paulo (Brazil)

    2012-12-15

    The stacking fault energy (SFE) in a set of experimental Ni-Cr-Fe alloys was determined using line profile analysis on synchrotron X-ray diffraction measurements. The methodology used here is supported by the Warren-Averbach calculations and the relationships among the stacking fault probability ({alpha}) and the mean-square microstrain (<{epsilon}{sup 2}{sub L}>). These parameters were obtained experimentally from cold-worked and annealed specimens extracted from the set of studied Ni-alloys. The obtained results show that the SFE in these alloys is strongly influenced by the kind and quantity of addition elements. Different effects due to the action of carbide-forming elements and the solid solution hardening elements on the SFE are discussed here. The simultaneous addition of Nb, Hf, and, Mo, in the studied Ni-Cr-Fe alloys have generated the stronger decreasing of the SFE. The relationships between SFE and the contributions on electronic structure from each element of additions were established.

  18. A Review of Solid-Solution Models of High-Entropy Alloys Based on Ab Initio Calculations

    Directory of Open Access Journals (Sweden)

    Fuyang Tian

    2017-11-01

    Full Text Available Similar to the importance of XRD in experiments, ab initio calculations, as a powerful tool, have been applied to predict the new potential materials and investigate the intrinsic properties of materials in theory. As a typical solid-solution material, the large degree of uncertainty of high-entropy alloys (HEAs results in the difficulty of ab initio calculations application to HEAs. The present review focuses on the available ab initio based solid-solution models (virtual lattice approximation, coherent potential approximation, special quasirandom structure, similar local atomic environment, maximum-entropy method, and hybrid Monte Carlo/molecular dynamics and their applications and limits in single phase HEAs.

  19. A Summary of Corrosion Properties of Al-Rich Solid Solution and Secondary Phase Particles in Al Alloys

    Directory of Open Access Journals (Sweden)

    Jichao Li

    2017-03-01

    Full Text Available The heterogeneous structure of Al alloys renders them susceptible to localized corrosion due to the different electrochemical properties existing in the Al-rich solid solution matrix and secondary phase particles. The galvanic interactions between these two phases can result in pit formation either through dissolution of the particles or corrosion of the matrix adjacent to the particles. This detrimentally localized corrosion behavior is closely related to the corrosion properties of the particles and the Al-rich matrix. The comprehensive characterization of this behavior under various and varying conditions is critical to understanding the mechanism of pit formation, selecting appropriate inhibitors, and developing protection strategies. The corrosion properties (corrosion potential, pitting potential and corrosion rate of both secondary phase particles and Al-solid solutions in Al alloys are summarized in this review, aiming to provide a database for corrosion research applicable to the localized corrosion of Al alloys.

  20. A Unified Physical Model for Creep and Hot Working of Al-Mg Solid Solution Alloys

    Directory of Open Access Journals (Sweden)

    Stefano Spigarelli

    2017-12-01

    Full Text Available The description of the dependence of steady-state creep rate on applied stress and temperature is almost invariably based on the Norton equation or on derived power-law relationships. In hot working, the Norton equation does not work, and is therefore usually replaced with the Garofalo (sinh equation. Both of these equations are phenomenological in nature and can be seldom unambiguously related to microstructural parameters, such as dislocation density, although early efforts in this sense led to the introduction of the “natural power law” with exponent 3. In an attempt to overcome this deficiency, a recent model with sound physical basis has been successfully used to describe the creep response of fcc metals, such as copper. The main advantage of this model is that it does not require any data fitting to predict the strain rate dependence on applied stress and temperature, which is a particularly attractive peculiarity when studying the hot workability of metals. Thus, the model, properly modified to take into account solid solution strengthening effects, has been here applied to the study of the creep and hot-working of simple Al-Mg single phase alloys. The model demonstrated an excellent accuracy in describing both creep and hot working regimes, still maintaining its most important feature, that is, it does not require any fitting of the experimental data.

  1. Structural and vibrational investigations on Ge{sub 34}Sb{sub 66} solid solutions produced by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Rebelo, Q.H.F.; Cotta, E.A. [Departamento de Física, Universidade Federal do Amazonas, 69077-000 Manaus, Amazonas (Brazil); Souza, S.M. de, E-mail: s.michielon@gmail.com [Departamento de Física, Universidade Federal do Amazonas, 69077-000 Manaus, Amazonas (Brazil); Trichês, D.M. [Departamento de Física, Universidade Federal do Amazonas, 69077-000 Manaus, Amazonas (Brazil); Machado, K.D. [Departamento de Física, Centro Politécnico, Universidade Federal do Paraná, 81531-990 Curitiba, Paraná (Brazil); Lima, J.C. de; Grandi, T.A. [Departamento de Física, Centro de Ciências Exatas, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, Santa Catarina (Brazil); Poffo, C.M. [Departamento de Eng. Mecânica, Centro de Ciências Tecnológicas, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, Santa Catarina (Brazil); Manzato, L. [Instituto Federal de Educação, Ciência e Tecnologia do Amazonas, 69075-351 Manaus, Amazonas (Brazil)

    2013-10-25

    Highlights: •A Ge{sub 34}Sb{sub 66} solid solution was prepared by mechanical alloying. •X-ray diffraction results indicate complete dissolution of Ge on the Sb matrix. •Raman measurements indicate the presence of nanocrystalline Ge dispersed in the matrix. -- Abstract: A nanostructured solid solution Ge{sub 34}Sb{sub 66} was produced from Ge and Sb by mechanical alloying and its structural and vibrational properties were investigated by X-ray diffraction (XRD) and micro-Raman spectroscopy. The Rietveld refinement of the XRD measurements allowed the investigation of the evolution of the solid solution with the milling time. The Bragg peaks of the Sb solvent phase showed a strongly reflection-indices-dependent line broadening due to the spatial variation of the Sb/Ge ratio. The asymmetric broadening in the deformed peaks was analyzed considering the Stephens model. Volume fractions of crystalline and interfacial components of the milled powder were estimated from the XRD patterns. Although XRD measurements indicated the formation of a solid solution, Raman measurements revealed the presence of nanocrystalline Ge, and its crystallite size was estimated from the Raman analysis.

  2. Comparison of the Solid Solution Properties of Mg-RE (Gd, Dy, Y Alloys with Atomistic Simulation

    Directory of Open Access Journals (Sweden)

    Yurong Wu

    2008-01-01

    Full Text Available Molecular dynamic simulations have been performed to study the solid solution mechanism of Mg100-xREx (RE=Gd,Dy,Y, x=0.5,1,2,3,4  at.%. The obtained results reveal that the additions of Gd, Dy and Y increase the lattice constants of Mg-RE alloys. Also the axis ratio c/a remains unchanged with increase in temperature, restraining the occurrence of nonbasal slip and twinning. Furthermore, it is confirmed that bulk modulus of Mg alloys can be increased remarkably by adding the Gd, Dy, Y, especially Gd, because the solid solubility of Gd in Mg decrease sharply with temperature in comparison with Dy and Y. Consequently, the addition of the RE can enhance the strength of Mg-based alloys, which is in agreement with the experimental results.

  3. Interstitial positions of tin ions in alpha-(FerichSn)(2)O-3 solid solutions prepared by mechanical alloying

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Lin, Rong; Nielsen, Kurt

    1997-01-01

    The microstructure of samples of 91, 85, and 71 mol % alpha-Fe-2-O-3-SnO2. prepared by mechanical alloying, has been studied by x-ray diffraction with Rietveld structure refinements, On the basis of the structure refinements to the whole x-ray diffraction patterns for the four as-milled samples......, it is found that tin ions do not substitute iron ions in the solid solution, although this model is generally assumed in the literature. The Sn4+ ions occupy the empty octahedral holes in the lattice of the alpha-Fe2O3 phase....

  4. Structural analysis and magnetic properties of solid solutions of Co–Cr system obtained by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Betancourt-Cantera, J.A. [Área Académica de Ciencias de la Tierra y Materiales, UAEH Carr., Pachuca-Tulancingo Km. 4.5, Pachuca, Hidalgo 42184 (Mexico); Sánchez-De Jesús, F., E-mail: fsanchez@uaeh.edu.mx [Área Académica de Ciencias de la Tierra y Materiales, UAEH Carr., Pachuca-Tulancingo Km. 4.5, Pachuca, Hidalgo 42184 (Mexico); Bolarín-Miró, A.M. [Área Académica de Ciencias de la Tierra y Materiales, UAEH Carr., Pachuca-Tulancingo Km. 4.5, Pachuca, Hidalgo 42184 (Mexico); Betancourt, I.; Torres-Villaseñor, G. [Departamento de Materiales Metálicos y Cerámicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México D.F. 04510 (Mexico)

    2014-03-15

    In this paper, a systematic study on the structural and magnetic properties of Co{sub 100−x}Cr{sub x} alloys (0alloying is presented. Co and Cr elemental powders were used as precursors, and mixed in an adequate weight ratio to obtain Co{sub 1−x}Cr{sub x} (0solid solutions based on Co-hcp, Co-fcc and Cr-bcc structures were obtained. The saturation polarization indicated a maximum value of 1.17 T (144 Am{sup 2}/kg) for the Co{sub 90}Cr{sub 10}, which decreases with the increasing of the Cr content up to x=80, as a consequence of the dilution effect of the magnetic moment which is caused by the Cr content and by the competition between ferromagnetic and antiferromagnetic exchange interactions. The coercivity increases up to 34 kA/m (435 Oe) for Co{sub 40}Cr{sub 60}. For Cr rich compositions, it is observed an important decrease reaching 21 kA/m (272 Oe) for Co{sub 10}Cr{sub 90,} it is related to the grain size and the structural change. Besides, the magnetic anisotropy constant was determined for each composition. Magnetic thermogravimetric analysis allowed to obtain Curie temperatures corresponding to the formation of hcp-Co(Cr) and fcc-Co(Cr) solid solutions. - Highlights: • Mechanical alloying (MA) induces the formation of solid solutions of Co–Cr system in non-equilibrium. • We report the crystal structure and the magnetic behavior of Co–Cr alloys produced by MA. • MA improves the magnetic properties of Co–Cr system.

  5. Evaluation of Solid-Solution Hardening in Several Binary Alloy Systems Using Diffusion Couples Combined with Nanoindentation

    Science.gov (United States)

    Kadambi, Sourabh B.; Divya, V. D.; Ramamurty, U.

    2017-10-01

    Analysis of solid-solution hardening (SSH) in alloys requires the synthesis of large composition libraries and the measurement of strength or hardness from these compositions. Conventional methods of synthesis and testing, however, are not efficient and high-throughput approaches have been developed in the past. In the present study, we use a high-throughput combinatorial approach to examine SSH at large concentrations in binary alloys of Fe-Ni, Fe-Co, Pt-Ni, Pt-Co, Ni-Co, Ni-Mo, and Co-Mo. The diffusion couple (DC) method is used to generate concentration ( c) gradients and the nanoindentation (NI) technique to measure the hardness ( H) along these gradients. The obtained H -c profiles are analyzed within the framework of the Labusch model of SSH, and the c^{2/3} dependence of H predicted by the model is found to be generally applicable. The SSH behavior obtained using the combinatorial method is found to be largely consistent with that observed in the literature using conventional and DC-NI methods. This study evaluates SSH in Fe-, Ni-, Co-, and Pt-based binary alloys and confirms the applicability of the DC-NI approach for rapidly screening various solute elements for their SSH ability.

  6. The effect of deformation treatment on the decomposition of supersaturated Ni(Nb,B) and Ni(Mo,B) solid solutions synthesized by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Kubalova, L.M., E-mail: kubal@yandex.ru [K.L. Khetagurov North-Ossetian State University, Vatutina Str. 44-46, Vladikavkaz 362025 (Russian Federation); Fadeeva, V.I., E-mail: fadeeva@general.chem.msu.ru [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation)

    2014-02-15

    Highlights: • Influence of deformation on decomposition of Ni-based solid solutions was studied. • X-ray diffraction analysis and scanning electron microscopy were used. • Decomposition of Ni(Nb,B), Ni(Mo,B) solid solutions takes place under deformation. • Formation of Ni{sub 21}(Nb,Mo){sub 2}B{sub 6}τ-phases after deformation treatment is observed. • Identity of MA and deformation on the decomposition of solid solutions is shown. -- Abstract: The effect of rotary-shear deformation during powders compacting on the decomposition of supersaturated Ni(Nb,B) and Ni(Mo,B) solid solutions is studied. The metastable fcc solid solutions were synthesized by mechanical alloying (MA) of the mixtures of components of Ni{sub 75}Nb{sub 12}B{sub 13} and Ni{sub 73}Mo{sub 14}B{sub 13} compositions. The powders were compacted on a Bridgman anvil. Col plastic deformation action is realized by using this technique. As a result the initial structure of nonequilibrium supersaturated solid solutions changed. The data of X-ray diffraction analysis and scanning electron microscopy showed a partial decomposition of Ni(Nb,B) and Ni(Mo,B) solid solutions, which leads to the formation of cubic boride τ phases – Ni{sub 21}Nb{sub 2}B{sub 6} with a lattice parameter of a = 1.0572 nm and, correspondingly, Ni{sub 21}Mo{sub 2}B{sub 6} phase with a lattice parameter of a = 1.0498 nm. The τ phase probably forms coherently to the fcc crystal lattice of solid solution because of its lattice parameter is equal to three lattice parameter of nickel. According to the data of local X-ray spectral analysis, the compacted alloys are heterogeneous and are contained boron-reach and also niobium- and molybdenum-rich regions.

  7. Formation of solid solutions of gallium in Fe–Cr and Fe–Co alloys: Mössbauer studies and first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Serikov, V.V. [Institute of Metal Physics UB RAS, S. Kovalevskaya str. 18, 620990 Ekaterinburg (Russian Federation); Kleinerman, N.M., E-mail: kleinerman@imp.uran.ru [Institute of Metal Physics UB RAS, S. Kovalevskaya str. 18, 620990 Ekaterinburg (Russian Federation); Vershinin, A.V.; Mushnikov, N.V.; Protasov, A.V.; Stashkova, L.A. [Institute of Metal Physics UB RAS, S. Kovalevskaya str. 18, 620990 Ekaterinburg (Russian Federation); Gorbatov, O.I. [Institute of Metal Physics UB RAS, S. Kovalevskaya str. 18, 620990 Ekaterinburg (Russian Federation); Department of Materials Science and Engineering, KTH Royal Institute of Technology, SE - 100 44 Stockholm (Sweden); Ruban, A.V. [Department of Materials Science and Engineering, KTH Royal Institute of Technology, SE - 100 44 Stockholm (Sweden); Gornostyrev, Yu.N. [Institute of Metal Physics UB RAS, S. Kovalevskaya str. 18, 620990 Ekaterinburg (Russian Federation)

    2014-11-25

    Highlights: • Structure features of the formation of quasibinary solid solutions Fe–Co–Ga and Fe–Cr–Ga are found. • The first-principles calculation of mixing and solubility energies for Ga in an Fe–X alloy are given. • Ga handicaps the processes of phase separation in the Fe–Cr system and ordering in the Fe–Co system. • Preference of Ga entering in the neighborhood of a second element can help study multielement alloys. - Abstract: Investigation of Ga influence on the structure of Fe–Cr and Fe–Co alloys was performed with the use of Mössbauer spectroscopy and X-ray diffraction methods. The experimental results are compared with results of first-principles calculations of the mixing and solubility energies for Ga in an Fe–X (X = Co, Cr) alloy both in ferromagnetic and paramagnetic states. It is shown that Ga mainly goes into the solid solutions of the base alloys. In the alloys of the Fe–Cr system, doping with Ga handicaps the decomposition of solid solutions, observed in the binary alloys, and increases its stability. In the alloys with Co, Ga also favors the uniformity of solid solutions. The results of the first-principles calculations testify in favor of a preferable dissolution of Ga in the FeCo regions of a multicomponent structure rather than FeCr regions, both types of regions being in the ferromagnetic state at the temperature of annealing. The analysis of Mössbauer experiments gives some grounds to conclude that if, owing to liquation, clusterization, or initial stages of phase separation, there exist regions enriched in iron, some amount of Ga atoms prefer to enter the nearest surroundings of iron atoms, thus forming binary Fe–Ga regions (or phases)

  8. A Study on Microstructural Change and Properties of Mg-1.4 wt%Ca-xwt%Zn Alloys by Two-Step Solid Solution and Aging Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Seong Mo; Kim, Hye Sung [Pusan National University, Busan (Korea, Republic of); Jeong, Ha-Guk [Korea Institute of Industrial Technology, Incheon (Korea, Republic of); Kim, Teak-Soo [Korea Institute of Industrial Technology, Incheon (Korea, Republic of)

    2015-09-15

    Optimum heat treatment conditions to improve the hardness and corrosion resistance of ternary Mg-Ca-Zn alloys have been studied, based on the theoretical models and DSC (Differential scanning calorimetry) experimental data. Two-step heating process at 420 ℃ and 480 ℃ has been applied and we have found that the low melting point phase, Ca{sub 2}Mg{sub 6}Zn{sub 3} can effectively be dissolved into α-Mg matrix without premature melting. Due to preceding treatment at lower temperature followed by the second stage solid solution heat treatment at 480 ℃, Mg-1.4 wt%Ca-xwt%Zn alloys (x=0, 1.5 and 4.0) exhibit improved corrosion resistance than that from the single step solid solution treated alloy at 480 ℃. However, aging treatment of the alloy at 200 ℃ has led to the homogeneous precipitation of Ca{sub 2}Mg{sub 6}Zn{sub 3} and Mg{sub 2}Ca phases in the matrix as well as at the grain boundary. This microstructural change results in the deterioration of corrosion resistance mainly originated from galvanic corrosion between the matrix and the precipitates. The hardness of Mg-1.4%Cax%Zn alloy, on the other hand, significantly increases with Zn addition by applying two-step solid solution and aging heat treatment.

  9. Effects of the Solid Solution Heat Treatment on the Corrosion Resistance Property of SSC13 Cast Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kuk-Jin [Hi-Sten Co., Ltd., Gimhae (Korea, Republic of); Lim, Su Gun [Gyeongsang National University, Jinju (Korea, Republic of); Pak, S. J. [Gachon BioNano Research Institute, Gachon University, Sungnam (Korea, Republic of)

    2015-04-15

    Recently, Stainless steels have been increasingly selected as the fitting or the valve materials of water pipes as the human health issue is getting higher and higher. Therefore, the connectors attached at pipes to deliver water are exposed to more severe environments than the pipes because crevice or galvanic corrosion is apt to occur at the fittings or the valves. Effects of the solid solution annealing, cooling rate after this heat treatment, and passivation on the corrosion properties of the shell mold casted SSC13 (STS304 alloy equivalent) were studied. The heating and quenching treatment more or less reduced hardness but effectively improved corrosion resistance. It was explained by the reduction of delta ferrite contents. Independent of heat treatment, the chemical passivation treatment also lowered corrosion rate but the improvement of corrosion resistance depended on temperature and time for passivation treatment indicating that the optimum conditions for passivation treatment were the bath temperature of 34 .deg. C and operating time of 10 minutes. Therefore it is suggested that the corrosion resistance of SSC13 can be effectively improved with the heat treatment, where SSC13 is heated for 10 minutes at 1120 °C and quenched and passivation treatment, where SSC13 is passivated for at least 10 seconds at 34 °C nitric acid solution.

  10. Characterization investigations during mechanical alloying and sintering of Ni-W solid solution alloys dispersed with WC and Y{sub 2}O{sub 3} particles

    Energy Technology Data Exchange (ETDEWEB)

    Genc, Aziz, E-mail: agenc@itu.edu.t [Particulate Materials Laboratories, Department of Metallurgical and Materials Engineering, Istanbul Technical University, Maslak, 34469 Istanbul (Turkey); Luetfi Ovecoglu, M. [Particulate Materials Laboratories, Department of Metallurgical and Materials Engineering, Istanbul Technical University, Maslak, 34469 Istanbul (Turkey)

    2010-10-15

    Research highlights: {yields} Characterization investigations on the Ni-W solid solution alloys fabricated via mechanical alloying and the evolution of the properties of the powders with increasing MA durations. {yields} Reinforcement of the selected Ni-W powders with WC and Y{sub 2}O{sub 3} particles and further MA together for 12 h. {yields} There is no reported literature on the development and characterization of Ni-W solid solution alloys matrix composites fabricated via MA. {yields} Sintering of the developed composites and the characterization investigations of the sintered samples. {yields} Identification of new 'pomegranate-like' structures in the bulk of the samples. - Abstract: Blended elemental Ni-30 wt.% W powders were mechanically alloyed (MA'd) for 1 h, 3 h, 6 h, 12 h, 24 h, 36 h and 48 h in a Spex mixer/mill at room temperature in order to investigate the effects of MA duration on the solubility of W in Ni and the grain size, hardness and particle size. Microstructural and phase characterizations of the MA'd powders were carried out using X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). On the basis of achieved saturation on the solid solubility, hardness and particle size, the Ni-30 wt.% W powders MA'd for 48 h were chosen as the matrix which was reinforced with different amounts of WC and/or with 1 wt.% Y{sub 2}O{sub 3} particles. The reinforced powders were further MA'd for 12 h. The MA'd powders were sintered at 1300 {sup o}C for 1 h under Ar and H{sub 2} gas flowing conditions. Microstructural characterizations of the sintered samples were conducted via XRD and SEM. Sintered densities were measured by using the Archimedes' method. Vickers microhardness tests were performed on both MA'd powders and the sintered samples. Sliding wear experiments were done in order to investigate wear behaviors of the sintered samples.

  11. Indications of the formation of an oversaturated solid solution during hydrogenation of Mg-Ni based nanocomposite produced by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Guzman, D. [Departamento de Ingenieria en Metalurgia, Facultad de Ingenieria, Universidad de Atacama y Centro Regional de Investigacion y Desarrollo Sustentable de Atacama, CRIDESAT, Av. Copayapu 485, Copiapo (Chile); Ordonez, S. [Departamento de Ingenieria Metalurgica, Facultad de Ingenieria, Universidad de Santiago de Chile, Av. Lib. Bernardo O' Higgins 3363, Santiago (Chile); Fernandez, J.F.; Sanchez, C. [Departamento de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco 28049, Madrid (Spain); Serafini, D. [Departamento de Fisica, Facultad de Ciencias, Universidad de Santiago de Chile and Center for Interdisciplinary Research in Materials, CIMAT, Av. Lib. Bernardo O' Higgins 3363, Santiago (Chile); Rojas, P.A. [Escuela de Ingenieria Mecanica, Facultad de Ingenieria, Av. Los Carrera 01567, Quilpue, Pontificia Universidad Catolica de Valparaiso, PUCV (Chile); Aguilar, C. [Instituto de Materiales y Procesos Termomecanicos, Facultad de Ciencias de la Ingenieria, Universidad Austral de Chile, Av. General Lagos 2086, Valdivia (Chile)

    2009-07-15

    An oversaturated solid solution of H in a nanocomposite material formed mainly by nanocrystalline Mg{sub 2}Ni, some residual nanocrystalline Ni and an Mg rich amorphous phase has been found for the first time. The nanocomposite was produced by mechanical alloying starting from Mg and Ni elemental powders, using a SPEX 8000D mill. The hydriding characterization of the nanocomposite was carried out by solid-gas reaction method in a Sievert's type apparatus. The maximum hydrogen content reached in a period of 21 Ks without prior activation was 2.00 wt.% H under hydrogen pressure of 2 MPa at 363 K. The X-ray diffraction analysis showed the presence of an oversaturated solid solution between nanocrystalline Mg{sub 2}Ni and H without any sign of Mg{sub 2}NiH{sub 4} hydride formation. The dehydriding behaviour was studied by differential scanning calorimetry and thermogravimetry. The results showed the existence of two desorption peaks, the first one associated with the transformation of the oversaturated solid solution into Mg{sub 2}NiH{sub 4}, and the second one with the Mg{sub 2}NiH{sub 4} desorption. (author)

  12. The Development of a Ti-6Al-4V Alloy via Oxygen Solid Solution Strengthening for Aerospace and Defense Applications

    Science.gov (United States)

    2013-03-01

    aerospace, marine , chemical industries, medical, and military applications (1, 2) because these alloys have high specific strength, high Young’s...conventional titanium alloys used in structural components contain many alloying elements of transition metals such as vanadium (V), niobium (Nb), chromium...process (5) was 23.7 μm and 99.5%, respectively. The content of TiO2 particles was 0 to ~1.5 mass% of the mixture. Next, the aluminum and vanadium

  13. Study on microstructure evolution of deformed Mg-Gd-Y-Nd-Zr heat-resistant magnesium alloys after solid solution and ageing

    Directory of Open Access Journals (Sweden)

    Jianmin Yu

    2016-01-01

    Full Text Available The microstructure evolution of Mg-Gd-Y-Nd-Zr heat-resistant magnesium alloy after deformation and T5 or T6 treatment were studied. In thermoplastic deformation, dynamic recrystallization and dynamic precipitation has been taken place at the same time. The dynamic precipitation reduces the recrystallization nucleation driving force in the grain; it will prevent to occur dynamic recrystallization partially. Solid solution temperature was 530oC and hold 4h. Age hardening treatments were performed at 225oC and hold 16h. The alloy showed the comprehensive properties are obviously improved from T6 to T5 heat treatment. After T5 heat treatment the tensile strength of alloy increased to 359.3 MPa, increased by around 48.5%; Elongation is increasing from 5.17% to 6.5%. After peak ageing treatment, the main precipitation is β' phase, the precipitation phase have obvious pinning effect to grain boundary of the alloy, it will prevent the grain growth ageing for a long-time. At the same time, strengthening role of precipitate phase make its strength increased significantly.

  14. Fabrication of Nb{sub 3}Al superconducting wires by utilizing the mechanically alloyed Nb(Al){sub ss} supersaturated solid-solution with low-temperature annealing

    Energy Technology Data Exchange (ETDEWEB)

    Pan, X.F. [National Engineering Laboratory for Superconducting Material, Western Superconducting Technologies (WST) Co., Ltd., Xi’an 710018 (China); Superconducting Materials Center, Northwest Institute for Nonferrous Metal Research, Xi’an 710016 (China); Yan, G., E-mail: gyan@c-nin.com [National Engineering Laboratory for Superconducting Material, Western Superconducting Technologies (WST) Co., Ltd., Xi’an 710018 (China); Superconducting Materials Center, Northwest Institute for Nonferrous Metal Research, Xi’an 710016 (China); Qi, M. [Superconducting Materials Center, Northwest Institute for Nonferrous Metal Research, Xi’an 710016 (China); Cui, L.J. [National Engineering Laboratory for Superconducting Material, Western Superconducting Technologies (WST) Co., Ltd., Xi’an 710018 (China); Chen, Y.L.; Zhao, Y. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), Superconductivity and New Energy R and D Center, Southwest Jiaotong University, Chengdu 610031 (China); Li, C.S. [Superconducting Materials Center, Northwest Institute for Nonferrous Metal Research, Xi’an 710016 (China); Liu, X.H. [National Engineering Laboratory for Superconducting Material, Western Superconducting Technologies (WST) Co., Ltd., Xi’an 710018 (China); Feng, Y.; Zhang, P.X. [National Engineering Laboratory for Superconducting Material, Western Superconducting Technologies (WST) Co., Ltd., Xi’an 710018 (China); Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), Superconductivity and New Energy R and D Center, Southwest Jiaotong University, Chengdu 610031 (China); Liu, H.J. [Institute of Plasma Physics, Chinese Academy of Sciences (CAS), Hefei 230031 (China); and others

    2014-07-15

    Highlights: • This paper reported superconducting properties of the powder-in-tube Nb{sub 3}Al wires. • The Nb{sub 3}Al wires were made by using Nb(Al){sub ss} supersaturated solid solution powders. • The Cu-matrix Nb{sub 3}Al superconducting wires have been successfully fabricated. • The transport J{sub c} of Nb{sub 3}Al wires at 4.2 K, 10 T is up to 12,700 A/cm{sup 2}. - Abstract: High-performance Nb{sub 3}Al superconducting wire is a promising candidate to the application of high-field magnets. However, due to the production problem of km-grade wires that are free from low magnetic field instability, the Nb{sub 3}Al wires made by rapid heating, quenching and transformation (RHQT) are still not available to the large-scale engineering application. In this paper, we reported the properties of the in situ powder-in-tube (PIT) Nb{sub 3}Al superconducting wires, which were made by using the mechanically alloyed Nb(Al){sub ss} supersaturated solid solution, as well as the low temperature heat-treatment at 800 °C for 10 h. The results show that Nb{sub 3}Al superconductors in this method possess very fine grains and well superconducting properties, though a little of Nb{sub 2}Al and Nb impurities still keep being existence at present work. At the Nb{sub 3}Al with a nominal 26 at.% Al content, the onset T{sub c} reaches 15.8 K. Furthermore, a series of Nb{sub 3}Al wires and tapes with various sizes have been fabricated; for the 1.0 mm-diameter wire, the J{sub c} at 4.2 K, 10 T and 14 T have achieved 12,700 and 6900 A/cm{sup 2}, respectively. This work suggests it is possible to develop high-performance Cu-matrix Nb{sub 3}Al superconducting wires by directly using the Nb(Al){sub ss} supersaturated solid-solution without the complex RHQT heat-treatment process.

  15. Phase characterization of the gamma decomposition of the U3Zr9Nb solid solution alloy during isothermal treatments at 300 deg C: preliminary work

    Energy Technology Data Exchange (ETDEWEB)

    Tanure, Leandro Paulo de Almeida Reis; Cantagalli, Natalia Mattar; Ferraz, Wilmar Barbosa; Braga, Daniel Martins; Santos, Ana Maria Matildes dos [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)], e-mail: ferrazw@cdtn.br

    2009-07-01

    Alloys of uranium with the composition of U3Zr9Nb have been investigated at CDTN. Investigations have shown that the metallurgical structures of uranium-rich alloys containing zirconium or niobium were quite similar to the structure of uranium alloys containing transitions metals. It has been known that additions of niobium and zirconium improve the properties of the uranium base alloys. In our work the starting materials were uranium of technical purity with about 500 ppm of metallic impurities, zirconium of purity 99.8 % and niobium of purity 99.9 %. Vacuum induction melting of these alloys were cast into ingots. The ingots were annealed and homogenized at 1000 deg C/24 hours in vacuum of < 10{sup -4} Torr, and cooled at a rate of 3 deg C/min to room temperature. These uranium alloys were then reheated to gamma phase at about 800 deg C, for 1 hour. After quenching in a tin bath at 300 deg C samples were subjected to aging treatments in the range from about 4 minutes to 48 hours. Th samples were characterized by X-ray diffraction, metallographic examination, quantitative analysis using energy dispersive X-ray spectrometry and Vickers microhardness test. The results of quenching samples from 800 deg C and aging to 300 deg C have not revealed phase decompositions of the gamma cubic phase into martensitic phases. (author)

  16. The Solid Solutions (Per2[PtxAu(1−x(mnt2]; Alloying Para- and Diamagnetic Anions in Two-Chain Compounds

    Directory of Open Access Journals (Sweden)

    Manuel Matos

    2017-06-01

    Full Text Available The α-(Per2[M(mnt2] compounds with M = Pt and Au are isostructural two-chain solids that in addition to partially oxidized conducting perylene chains also contain anionic chains that can be either paramagnetic in the case of M = Pt or diamagnetic for M = Au. The electrical transport and magnetic properties of the solid solutions (Per2[Ptx-Au(1−x(mnt2] were investigated. The incorporation of paramagnetic [Pt(mnt2] impurities in the diamagnetic chains, and the effect of breaking the paramagnetic chains with diamagnetic centers for the low and high Pt range of concentrations were respectively probed. In the low Pt concentration range, there is a fast decrease of the metal-to-insulator transition from 12.4 K in the pure Au compound to 9.7 K for x = 0.1 comparable to the 8.1 K in the pure Pt compound. In the range x = 0.50−0.95, only β-phase crystals could be obtained. The spin-Peierls transition of the pure Pt compound, simultaneous with metal-to-insulator (Peierls transition is still present for 2% of diamagnetic impurities (x = 0.98 with transition temperature barely affected. Single crystal X-ray diffraction data obtained a high-quality structural refinement of the α-phase of the Au and Pt compounds. The β-phase structure was found to be composed of ordered layers with segregated donors and anion stacks, which alternate with disordered layers. The semiconducting properties of the β-phase are due to the disorder localization effects.

  17. Semiconductor Solid-Solution Nanostructures: Synthesis, Property Tailoring, and Applications.

    Science.gov (United States)

    Liu, Baodan; Li, Jing; Yang, Wenjin; Zhang, Xinglai; Jiang, Xin; Bando, Yoshio

    2017-12-01

    The innovation of band-gap engineering in advanced materials caused by the alloying of different semiconductors into solid-solution nanostructures provides numerous opportunities and advantages in optoelectronic property tailoring. The semiconductor solid-solution nanostructures have multifarious emission wavelength, adjustability of absorption edge, tunable electrical resistivity, and cutting-edge photoredox capability, and these advantages can be rationalized by the assorted synthesis strategies such as, binary, ternary, and quaternary solid-solutions. In addition, the abundance of elements in groups IIB, IIIA, VA, VIA, and VIIA provides sufficient room to tailor-make the semiconductor solid-solution nanostructures with the desired properties. Recent progress of semiconductor solid-solution nanostructures including synthesis strategies, structure and composition design, band-gap engineering related to the optical and electrical properties, and their applications in different fields is comprehensively reviewed. The classification, formation principle, synthesis routes, and the advantage of semiconductor solid-solution nanostructures are systematically reviewed. Moreover, the challenges faced in this area and the future prospects are discussed. By combining the information together, it is strongly anticipated that this Review may shed new light on understanding semiconductor solid-solution nanostructures while expected to have continuous breakthroughs in band-gap engineering and advanced optoelectronic nanodevices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Modelling solid solutions with cluster expansion, special quasirandom structures, and thermodynamic approaches

    Science.gov (United States)

    Saltas, V.; Horlait, D.; Sgourou, E. N.; Vallianatos, F.; Chroneos, A.

    2017-12-01

    Modelling solid solutions is fundamental in understanding the properties of numerous materials which are important for a range of applications in various fields including nanoelectronics and energy materials such as fuel cells, nuclear materials, and batteries, as the systematic understanding throughout the composition range of solid solutions for a range of conditions can be challenging from an experimental viewpoint. The main motivation of this review is to contribute to the discussion in the community of the applicability of methods that constitute the investigation of solid solutions computationally tractable. This is important as computational modelling is required to calculate numerous defect properties and to act synergistically with experiment to understand these materials. This review will examine in detail two examples: silicon germanium alloys and MAX phase solid solutions. Silicon germanium alloys are technologically important in nanoelectronic devices and are also relevant considering the recent advances in ternary and quaternary groups IV and III-V semiconductor alloys. MAX phase solid solutions display a palette of ceramic and metallic properties and it is anticipated that via their tuning they can have applications ranging from nuclear to aerospace industries as well as being precursors for particular MXenes. In the final part, a brief summary assesses the limitations and possibilities of the methodologies discussed, whereas there is discussion on the future directions and examples of solid solution systems that should prove fruitful to consider.

  19. Radionuclide solubility control by solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, F.; Klinkenberg, M.; Rozov, K.; Bosbach, D. [Forschungszentrum Juelich GmbH (Germany). Inst. of Energy and Climate Research - Nuclear Waste Management and Reactor Safety (IEK-6); Vinograd, V. [Frankfurt Univ. (Germany). Inst. of Geosciences

    2015-07-01

    The migration of radionuclides in the geosphere is to a large extend controlled by sorption processes onto minerals and colloids. On a molecular level, sorption phenomena involve surface complexation, ion exchange as well as solid solution formation. The formation of solid solutions leads to the structural incorporation of radionuclides in a host structure. Such solid solutions are ubiquitous in natural systems - most minerals in nature are atomistic mixtures of elements rather than pure compounds because their formation leads to a thermodynamically more stable situation compared to the formation of pure compounds. However, due to a lack of reliable data for the expected scenario at close-to equilibrium conditions, solid solution systems have so far not been considered in long-term safety assessments for nuclear waste repositories. In recent years, various solid-solution aqueous solution systems have been studied. Here we present state-of-the art results regarding the formation of (Ra,Ba)SO{sub 4} solid solutions. In some scenarios describing a waste repository system for spent nuclear fuel in crystalline rocks {sup 226}Ra dominates the radiological impact to the environment associated with the potential release of radionuclides from the repository in the future. The solubility of Ra in equilibrium with (Ra,Ba)SO{sub 4} is much lower than the one calculated with RaSO{sub 4} as solubility limiting phase. Especially, the available literature data for the interaction parameter W{sub BaRa}, which describes the non-ideality of the solid solution, vary by about one order of magnitude (Zhu, 2004; Curti et al., 2010). The final {sup 226}Ra concentration in this system is extremely sensitive to the amount of barite, the difference in the solubility products of the end-member phases, and the degree of non-ideality of the solid solution phase. Here, we have enhanced the fundamental understanding regarding (1) the thermodynamics of (Ra,Ba)SO{sub 4} solid solutions and (2) the

  20. The growth and tensile deformation behavior of the silver solid solution phase with zinc

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jiaqi, E-mail: jiaqw10@uci.edu [Department of Electrical Engineering and Computer Science, University of California, Irvine, CA 92697-2660 (United States); Materials and Manufacturing Technology, University of California, Irvine, CA 92697-2660 (United States); Lee, Chin C. [Department of Electrical Engineering and Computer Science, University of California, Irvine, CA 92697-2660 (United States); Materials and Manufacturing Technology, University of California, Irvine, CA 92697-2660 (United States)

    2016-06-21

    The growth of homogeneous silver solid solution phase with zinc are conducted at two different compositions. X-ray diffraction (XRD) and Scanning electron microscope/Energy dispersive X-ray spectroscopy (SEM/EDX) are carried out for phase identification and chemical composition verification. The mechanical properties of silver solid solution phase with zinc are evaluated by tensile test. The engineering and true stress vs. strain curves are presented and analyzed, with those of pure silver in comparison. According to the experimental results, silver solid solution phase with zinc at both compositions show tempered yield strength, high tensile strength and large uniform strain compared to those of pure silver. Fractography further confirmed the superior ductility of silver solid solution phase with zinc at both compositions. Our preliminary but encouraging results may pave the way for the silver based alloys to be applied in industries such as electronic packaging and structure engineering.

  1. Synthesis of solid solutions of perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Dambekalne, M.Y.; Antonova, M.K.; Perro, I.T.; Plaude, A.V.

    1986-03-01

    The authors carry out thermographic studies, using a derivatograph, in order to understand the nature of the processes taking place during the synthesis of solid solutions of perovskites. Based on the detailed studies on the phase transformations occurring in the charges of the PSN-PMN solid solutions and on the selection of the optimum conditions for carrying out their synthesis, the authors obtained a powder containing a minimum quantity of the undesirable pyrochlore phase and by sintering it using the hot pressing method, they produced single phase ceramic specimens containing the perovskite phase alone with a density close to the theoretical value and showing zero apparent porosity and water absorption.

  2. Superhard Rhenium/Tungsten Diboride Solid Solutions.

    Science.gov (United States)

    Lech, Andrew T; Turner, Christopher L; Lei, Jialin; Mohammadi, Reza; Tolbert, Sarah H; Kaner, Richard B

    2016-11-02

    Rhenium diboride (ReB 2 ), containing corrugated layers of covalently bonded boron, is a superhard metallic compound with a microhardness reaching as high as 40.5 GPa (under an applied load of 0.49 N). Tungsten diboride (WB 2 ), which takes a structural hybrid between that of ReB 2 and AlB 2 , where half of the boron layers are planar (as in AlB 2 ) and half are corrugated (as in ReB 2 ), has been shown not to be superhard. Here, we demonstrate that the ReB 2 -type structure can be maintained for solid solutions of tungsten in ReB 2 with tungsten content up to a surprisingly large limit of nearly 50 atom %. The lattice parameters for the solid solutions linearly increase along both the a- and c-axes with increasing tungsten content, as evaluated by powder X-ray and neutron diffraction. From micro- and nanoindentation hardness testing, all of the compositions within the range of 0-48 atom % W are superhard, and the bulk modulus of the 48 atom % solid solution is nearly identical to that of pure ReB 2 . These results further indicate that ReB 2 -structured compounds are superhard, as has been predicted from first-principles calculations, and may warrant further studies into additional solid solutions or ternary compounds taking this structure type.

  3. Thermal properties of spinel based solid solutions

    Science.gov (United States)

    O'Hara, Kelley Rae

    Solid solution formation in spinel based systems proved to be a viable approach to decreasing thermal conductivity. Samples with systematically varied additions of MgGa2O4 to MgAl2O 4 were prepared and thermal diffusivity was measured using the laser flash technique. Additionally, heat capacity was measured using differential scanning calorimetry and modeled for the MgAl2O4-MgGa 2O4 system. At 200°C thermal conductivity decreased 24% with a 5 mol% addition of MgGa2O4 to the system. The solid solution continued to decrease the thermal conductivity by 13% up to 1000°C with 5 mol% addition. The decrease in thermal conductivity ultimately resulted in a decrease in heat flux when applied to a theoretical furnace lining, which could lead to energy savings in industrial settings. The MgAl2O4-Al2O3 phase equilibria was investigated to fully understand the system and the thermal properties at elevated temperatures. The solvus line between MgAl2O4 and Al2O3 has been defined at 79.6 wt% Al 2O3 at 1500°C, 83.0 wt% Al2O4 at 1600°C, and 86.5 wt% Al2O3 at 1700°C. A metastable region has been identified at temperatures up to 1700°C which could have significant implications for material processing and properties. The spinel solid solution region has been extended to form an infinite solid solution with Al2O3 at elevated temperatures. A minimum in melting at 1975°C and a chemistry of 96 wt% Al2O3 rather than a eutectic is present. Thermal properties in the MgAl2O4-Al2O 3 system were investigated in both the single phase solid solution region and the two phase region. The thermal diffusivity decreased through the MgAl 2O4 solid solution region and was at a minimum through the entire metastable (nucleation and growth) region. As Al2O 3 became present as a second phase the thermal diffusivity increased with Al2O3 content. There was an 11.7% increase in thermal diffusivity with a change in overall chemistry of 85.20 wt% Al2O 3 to 87.71 wt% Al2O3, due to the drastic change in

  4. Structural, thermodynamic, and mechanical properties of WCu solid solutions

    Science.gov (United States)

    Liang, C. P.; Wu, C. Y.; Fan, J. L.; Gong, H. R.

    2017-11-01

    Various properties of Wsbnd Cu solid solutions are systematically investigated through a combined use of first-principles calculation, cluster expansion, special quasirandom structures (SQS), and lattice dynamics. It is shown that SQS are effective to unravel the intrinsic nature of solid solutions, and that BCC and FCC W100-xCux solid solutions are energetically more stable when 0 ≤ x ≤ 70 and 70 thermodynamic properties of Wsbnd Cu, and that the coefficients of thermal expansion of W100-xCux solid solutions are much lower than those of corresponding mechanical mixtures. In addition, the G/B values of W100-xCux solid solutions reach a minimum at x = 50, which is fundamentally due to the softening of phonons as well as strong chemical bonding between W and Cu with a mainly metallic feature.

  5. End-Member Formulation of Solid Solutions and Reactive Transport

    Energy Technology Data Exchange (ETDEWEB)

    Lichtner, Peter C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    A model for incorporating solid solutions into reactive transport equations is presented based on an end-member representation. Reactive transport equations are solved directly for the composition and bulk concentration of the solid solution. Reactions of a solid solution with an aqueous solution are formulated in terms of an overall stoichiometric reaction corresponding to a time-varying composition and exchange reactions, equivalent to reaction end-members. Reaction rates are treated kinetically using a transition state rate law for the overall reaction and a pseudo-kinetic rate law for exchange reactions. The composition of the solid solution at the onset of precipitation is assumed to correspond to the least soluble composition, equivalent to the composition at equilibrium. The stoichiometric saturation determines if the solid solution is super-saturated with respect to the aqueous solution. The method is implemented for a simple prototype batch reactor using Mathematica for a binary solid solution. Finally, the sensitivity of the results on the kinetic rate constant for a binary solid solution is investigated for reaction of an initially stoichiometric solid phase with an undersaturated aqueous solution.

  6. Solid solution strengthening and diffusion in nickel- and cobalt-based superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, Hamad ur

    2016-07-01

    Nickel and cobalt-based superalloys with a γ-γ{sup '} microstructure are known for their excellent creep resistance at high temperatures. Their microstructure is engineered using different alloying elements, that partition either to the fcc γ matrix or to the ordered γ{sup '} phase. In the present work the effect of alloying elements on their segregation behaviour in nickel-based superalloys, diffusion in cobalt-based superalloys and the temperature dependent solid solution strengthening in nickel-based alloys is investigated. The effect of dendritic segregation on the local mechanical properties of individual phases in the as-cast, heat treated and creep deformed state of a nickel-based superalloy is investigated. The local chemical composition is characterized using Electron Probe Micro Analysis and then correlated with the mechanical properties of individual phases using nanoindentation. Furthermore, the temperature dependant solid solution hardening contribution of Ta, W and Re towards fcc nickel is studied. The room temperature hardening is determined by a diffusion couple approach using nanoindentation and energy dispersive X-ray analysis for relating hardness to the chemical composition. The high temperature properties are determined using compression strain rate jump tests. The results show that at lower temperatures, the solute size is prevalent and the elements with the largest size difference with nickel, induce the greatest hardening consistent with a classical solid solution strengthening theory. At higher temperatures, the solutes interact with the dislocations such that the slowest diffusing solute poses maximal resistance to dislocation glide and climb. Lastly, the diffusion of different technically relevant solutes in fcc cobalt is investigated using diffusion couples. The results show that the large atoms diffuse faster in cobalt-based superalloys similar to their nickel-based counterparts.

  7. Heterogeneous Ferroelectric Solid Solutions Phases and Domain States

    CERN Document Server

    Topolov, Vitaly

    2012-01-01

    The book deals with perovskite-type ferroelectric solid solutions for modern materials science and applications, solving problems of complicated heterophase/domain structures near the morphotropic phase boundary and applications to various systems with morphotropic phases. In this book domain state–interface diagrams are presented for the interpretation of heterophase states in perovskite-type ferroelectric solid solutions. It allows to describe the stress relief in the presence of polydomain phases, the behavior of unit-cell parameters of coexisting phases and the effect of external electric fields. The novelty of the book consists in (i) the first systematization of data about heterophase states and their evolution in ferroelectric solid solutions (ii) the general interpretation of heterophase and domain structures at changing temperature, composition or electric field (iii) the complete analysis of interconnection domain structures, unit-cell parameters changes, heterophase structures and stress relief.

  8. Thermal conductivity of halide solid solutions: measurement and prediction.

    Science.gov (United States)

    Gheribi, Aïmen E; Poncsák, Sándor; St-Pierre, Rémi; Kiss, László I; Chartrand, Patrice

    2014-09-14

    The composition dependence of the lattice thermal conductivity in NaCl-KCl solid solutions has been measured as a function of composition and temperature. Samples with systematically varied compositions were prepared and the laser flash technique was used to determine the thermal diffusivity from 373 K to 823 K. A theoretical model, based on the Debye approximation of phonon density of state (which contains no adjustable parameters) was used to predict the thermal conductivity of both stoichiometric compounds and fully disordered solid solutions. The predictions obtained with the model agree very well with our measurement. A general method for predicting the thermal conductivity of different halide systems is discussed.

  9. Characterization of nanostructured alpha-Fe2O3-SnO2 solid solutions prepared by high energy ball milling

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Lin, R.; Mørup, Steen

    1998-01-01

    Solid solutions of SnO2 in alpha-Fe2O3 with SnO2 contents up to 20+-4 mol% have been prepared by mechanical alloying of alpha-Fe2O3 and SnO2 powder blends. X-ray diffraction and Mossbauer spectroscopy investigations show that the mechanical milling results in alloying on an atomic scale...... and that true solid solution formation occurs. We suggest that the high defect concentration and the chemical enthalpy of Fe3+ -O2- -Sn4+ interfaces between nanostructured alpha-Fe2O3 and SnO2 regions may serve as a driving force for the formation of a solid solution in the immiscible ceramic system....

  10. Effect of carbon on formation of mixed solid solutions during mechanochemical synthesis of Ni-Al-Mo-C mixtures and ordering of solutions during heating

    Science.gov (United States)

    Portnoi, V. K.; Leonov, A. V.; Streletskii, A. N.; Logacheva, A. I.

    2014-03-01

    Solid solutions Ni(Al, Mo, C) are formed via milling the Ni2.8Al1Mo0.2 and Ni3Al0.8Mo0.2 and graphite-containing Ni2.8Al1Mo0.2C(0.25, 0.5) and Ni3Al0.8Mo0.2C(0.25, 0.5) mixtures. In this case, some amount of Mo remains beyond the solid solution. Graphite added to a starting mixture decreases the Mo solubility and favors the amorphization of solid solutions. The complete amorphization was found for the mixture with the 5 at % C and 5 at % Mo, which was added instead of Ni. The heating of mechanically synthesized (MS) powder alloys leads to the ordering of carbon-free and carbon-containing solid solutions with the formation of the L12 and E21 structure, respectively. In the course of the ordering of the Ni(Al, Mo, C) solid solutions, Mo and carbon precipitate in the form of the molybdenum carbide (Mo2C) second phase. The hardness of the MS three-phase Ni-Al-Mo-C solid solutions subjected to hot isostatic pressing is determined by the mass fraction of the formed Mo2C carbide. It is shown that the carbon content in the multicomponent antiperovskite can be estimated by analyzing the ratio of integral intensities of superlattice reflections I (100)/ I (110).

  11. Relations between the modulus of elasticity of binary alloys and their structure

    Science.gov (United States)

    Koster, Werner; Rauscher, Walter

    1951-01-01

    A comprehensive survey of the elastic modulus of binary alloys as a function of the concentration is presented. Alloys that form continuous solid solutions, limited solid solutions, eutectic alloys, and alloys with intermetallic phases are investigated. Systems having the most important structures have been examined to obtain criteria for the relation between lattice structure, type of binding, and elastic behavior.

  12. Design principles for radiation-resistant solid solutions

    Science.gov (United States)

    Schuler, Thomas; Trinkle, Dallas R.; Bellon, Pascal; Averback, Robert

    2017-05-01

    We develop a multiscale approach to quantify the increase in the recombined fraction of point defects under irradiation resulting from dilute solute additions to a solid solution. This methodology provides design principles for radiation-resistant materials. Using an existing database of solute diffusivities, we identify Sb as one of the most efficient solutes for this purpose in a Cu matrix. We perform density-functional-theory calculations to obtain binding and migration energies of Sb atoms, vacancies, and self-interstitial atoms in various configurations. The computed data informs the self-consistent mean-field formalism to calculate transport coefficients, allowing us to make quantitative predictions of the recombined fraction of point defects as a function of temperature and irradiation rate using homogeneous rate equations. We identify two different mechanisms according to which solutes lead to an increase in the recombined fraction of point defects; at low temperature, solutes slow down vacancies (kinetic effect), while at high temperature, solutes stabilize vacancies in the solid solution (thermodynamic effect). Extension to other metallic matrices and solutes are discussed.

  13. Synthesis and characterization of cadmium-calcium hydroxyapatite solid solutions

    Science.gov (United States)

    Zhao, Xin; Zhu, Yi-nian; Dai, Liu-qin

    2014-06-01

    A series of cadmium-calcium hydroxyapatite solid solutions was prepared by an aqueous precipitation method. By various means, the characterizations confirmed the formation of continuous solid solutions over all ranges of Cd/(Cd+Ca) atomic ratio. In the results, both lattice parameters a and c display slight deviations from Vegard's rule when the Cd/(Cd+Ca) atomic ratio is greater than 0.6. The particles change from smaller acicular to larger hexagonal columnar crystals as the Cd/(Cd+Ca) atomic ratio increases from 0-0.60 to 0.60-1.00. The area of the phosphate peak for symmetric P-O stretching decreases with the increase in Cd/(Cd+Ca) atomic ratio, and the peak disappears when the Cd/(Cd+Ca) atomic ratio is greater than 0.6; the two phosphate peaks of P-O stretching gradually merge together for the Cd/(Cd+Ca) atomic ratio near 0.60. These variations can be explained by a slight tendency of larger Cd ions to occupy M(2) sites and smaller Ca ions to prefer M(1) sites in the structure.

  14. Synthesis and characterization of solid solutions in ABCO 4 system

    Science.gov (United States)

    Novoselov, A.; Zimina, G.; Komissarova, L.; Pajaczkowska, A.

    2006-01-01

    Formation of continuous solid solutions with a tetragonal structure of K 2NiF 4-type was investigated by direct solid-state synthesis, carbonate precipitations, the freeze-drying method and the Czochralski crystal growth technique. In the systems of SrLaAlO 4-CaLaAlO 4, SrNdAlO 4-CaNdAlO 4, SrPrAlO 4-CaPrAlO 4, SrLaAlO 4-SrLaGaO 4 and SrLaAlO 4-SrLaFeO 4 solid solutions are formed in the whole concentration range (0.0⩽ x⩽1.0) and in the systems of SrLaAlO 4-SrLaMnO 4 and SrLaAlO 4-SrLaCrO 4 in the limited compositional interval of (0.0⩽ x⩽0.20) and (0.0⩽ x⩽0.25), respectively, with composition dependency of lattice constants following Vegard's law.

  15. Dynamic Aspects of Solid Solution Cathodes for Electrochemical Power Sources

    DEFF Research Database (Denmark)

    Atlung, Sven; West, Keld; Jacobsen, Torben

    1979-01-01

    Battery systems based on alkali metal anodes and solid solution cathodes,i.e., cathodes based on the insertion of the alkali cation in a "host lattice,"show considerable promise for high energy density storage batteries. Thispaper discusses the interaction between battery requirements, in particu......Battery systems based on alkali metal anodes and solid solution cathodes,i.e., cathodes based on the insertion of the alkali cation in a "host lattice,"show considerable promise for high energy density storage batteries. Thispaper discusses the interaction between battery requirements......, in particularfor vehicle propulsion, and electrochemical and constructional factors. It isargued that the energy obtainable at a given load is limited by saturation ofthe surface layers of cathode particles with cations, and that the time beforesaturation occurs is determined by diffusion of cations and electrons...... into thehost lattice. Expressions are developed for plane, cylindrical, and sphericalparticles, giving the relation between battery load and the amount of cathodematerial utilized before saturation. The particle shape and a single parameterQ is used to describe cathode performance. Q is the ratio between...

  16. Nonisothermal nucleation in a solid solution of CuCl in glass: Concentration effect upon heating of the solid solution

    Science.gov (United States)

    Leiman, V. I.; Ashkalunin, A. L.; Derkacheva, O. Yu.; Maksimov, V. M.

    2017-09-01

    The influence of the heating rate of a solid solution of CuCl in glass on the size distribution of the produced CuCl nanoparticles is studied. The distribution curves of CuCl nanocrystals are determined by the method of exciton-thermal analysis. It is established that the concentration of CuCl nanoparticles increases by ten times upon slowing the sample heating process from 2 to 60 min, while the mean radius of particles decreases almost twice. The concentration of CuCl nanoparticles passes through a maximum in the process of heating the sample. The numerical simulation of the nucleation upon slow heating of a solid solution showed that the formation of the concentration maximum of the new phase clusters is determined by a rapid increase in the critical radius owing to an increase in temperature and decrease in the solution supersaturation. As a result, the formation of new phase nuclei ceases at a certain temperature, and a part of the previously formed clusters dissolves.

  17. Thermodynamic properties of hematite — ilmenite — geikielite solid solutions

    Science.gov (United States)

    Ghiorso, Mark S.

    1990-11-01

    A solution model is developed for rhombohedral oxide solid solutions having compositions within the ternary system ilmenite [(Fe{2+/ s }Ti{4+/1- s }) A (Fe{2+/1- s }Ti{4+/s}) B O3]-geikielite [(Mg{2+/ t }Ti{4+/1- t }) A (Mg{2+/1- t }Ti{4+/ t }) B O3]-hematite [(Fe3+) A (Fe3+) B O3]. The model incorporates an expression for the configurational entropy of solution, which accounts for varying degrees of structural long-range order (0≤s, t≤1) and utilizes simple regular solution theory to characterize the excess Gibbs free energy of mixing within the five-dimensional composition-ordering space. The 13 model parameters are calibrated from available data on: (1) the degree of long-range order and the composition-temperature dependence of theRbar 3c - Rbar 3 transition along the ilmenite-hematite binary join; (2) the compositions of coexisting olivine and rhombohedral oxide solid solutions close to the Mg-Fe2+ join; (3) the shape of the miscibility gap along the ilmenite-hematite join; (4) the compositions of coexisting spinel and rhombohedral oxide solid solutions along the Fe2+-Fe3+ join. In the course of calibration, estimates are obtained for the reference state enthalpy of formation of ulvöspinel and stoichiometric hematite (-1488.5 and -822.0 kJ/mol at 298 K and 1 bar, respectively). The model involves no excess entropies of mixing nor does it incorporate ternary interaction parameters. The formulation fits the available data and represents an internally consistent energetic model when used in conjuction with the standard state thermodynamic data set of Berman (1988) and the solution theory for orthopyroxenes, olivines and Fe-Mg titanomagnetite-aluminate-chromate spinels developed by Sack and Ghiorso (1989, 1990a, b). Calculated activity-composition relations for the end-members of the series, demonstrate the substantial degree of nonideality associated with interactions between the ordered and disordered structures and the dominant influence of the miscibility

  18. Magnetic clusters in ilmenite-hematite solid solutions

    DEFF Research Database (Denmark)

    Frandsen, Cathrine; Burton, B. P.; Rasmussen, Helge Kildahl

    2010-01-01

    We report the use of high-field 57Fe Mössbauer spectroscopy to resolve the magnetic ordering of ilmenite-hematite [xFeTiO3−(1−x)Fe2O3] solid solutions with x>0.5. We find that nanometer-sized hematite clusters exist within an ilmenite-like matrix. Although both phases are antiferromagnetically...... ordered, the hematite clusters show ferrimagnetic behavior due to superexchange coupling with Fe2+ in ilmenite. For ilmenite-rich samples (x=0.95), the clusters are isolated and superparamagnetic. For more hematite-rich samples with x=0.80 and x=0.70, the clusters interact to form a cluster glass....

  19. Luminescence spectra and kinetics of disordered solid solutions

    DEFF Research Database (Denmark)

    Klochikhin, A.; Reznitsky, A.; Permogorov, S.

    1999-01-01

    for the temporal evolution of the luminescence band. It is shown that the changes of band shape with time come from the interplay of population dynamics of extended states and spatially isolated ''radiative" states. Finally, the measurements of the decay of the spectrally integrated luminescence intensity at long......We have studied both theoretically and experimentally the luminescence spectra and kinetics of crystalline, disordered solid solutions after pulsed excitation. First, we present the model calculations of the steady-state luminescence band shape caused by recombination of excitons localized...... only a relatively small group of ''radiative" states forms the steady-state luminescence band. The continuum percolation theory is applied to distinguish the ''radiative'' localized states, which are isolated in space and have no ways for nonradiative transitions along the tail states. It is found...

  20. Modeling of the evolution of a dislocation structure and development of microplastic deformation in single crystals of fcc substitutional solid solutions

    Science.gov (United States)

    Kulagina, V. V.; Dudarev, E. F.; Rudchenko, V. V.

    1980-07-01

    An analysis is made of evolution of a dislocation structure during the initial stage of plastic deformation and the stress-strain diagrams are derived theoretically for single crystals of fcc substitutional solid solutions. The example of Cu-Al alloys is used to confirm the theoretically predicted relationship between the stress and strain, and also between the flow stress and the resistance to the motion of a single dislocation.

  1. Thermal Expansion of Fluorapatite-Chlorapatite Solid Solutions

    Science.gov (United States)

    Hovis, Guy; Abraham, Tony; Hudacek, William; Wildermuth, Sarah; Scott, Brian; Altomare, Caitlin; Medford, Aaron; Conlon, Maricate; Morris, Matthew; Leaman, Amanda; Almer, Christine; Tomaino, Gary; Harlov, Daniel

    2015-04-01

    X-ray powder diffraction experiments have been performed on fifteen fluorapatite-chlorapatite solid solutions synthesized and chemically characterized at the GeoForschungsZentrum - Potsdam (Hovis and Harlov, 2010; Schettler, Gottschalk, and Harlov, 2011), as well as two natural near-end-member samples, from room temperature to ~900 °C at 50 to 75 °C intervals. NIST 640a Si was employed as an internal standard; data from Parrish (1953) were used to determine Si peak positions at elevated temperatures. Unit-cell parameters calculated using the software of Holland and Redfern (1997) result in volume-temperature (V-T) plots that are linear or slightly concave up (V plotted as the vertical axis) over the T range investigated. Relations for the "a" and "c" unit-cell dimensions with T for these hexagonal minerals are nearly linear, but as with V, commonly improved by quadratic fits to the data. Coefficients of thermal expansion for volume (αV ), calculated as (1/V0°C) x (ΔV/ΔT) based on linear V-T relationships, mostly fall within the range 42 ± 2 x 10-6 deg-1 and show no obvious dependence on composition. Thermal expansion coefficients for individual unit-cell axes, however, do show clear relationships to composition, αa increasing from ~9.5 to ~13.5 x 10-6 deg-1 and αc decreasing from ~19.5 to ~13 x 10-6 deg-1 from the Cl to the F end member. Clearly, a compensating structural relationship accounts for the observed relationships. Such compositional dependence was not seen in the thermal expansion data for F-OH apatite solid solutions (Hovis, Scott, Altomare, Leaman, Morris, and Tomaino, American Mineralogist, in press). This difference can be explained by the similar sizes of F- and (OH)- versus the much greater size contrast between F- and Cl-. Sincere thanks to the National Science Foundation for support of this work, which has provided numerous research experiences for Lafayette College undergraduates. Thanks also to the Earth Sciences Department, University

  2. Solid solutions based on lead-barium metaniobate

    Energy Technology Data Exchange (ETDEWEB)

    Gridnev, S.A.; Barmina, N.V.; Pavlova, N.G.; Parfenova, N.N.; Smirnova, E.P. (Voronezhskij Politekhnicheskij Inst. (USSR); AN SSSR, Moscow. Fiziko-Tekhnicheskij Inst.)

    1982-10-01

    Piezoceramic materials based on solid solutions of (1-x-y-z), PbNb/sub 2/O/sub 6/+xBaNb/sub 2/O/sub 6/+yPb/sub 2/Ti/sub 2/O/sub 6/+zNa/sub 2/Nb/sub 2/O/sub 6/ composition with high Curie temperatures (470-600 deg) are prepared. Polarization conditions are determined and materials with high values of piezomodules d/sub 33/=(40-50)x10/sup -12/ K/N and d/sub 31/=5.3x10/sup -12/ K/N are prepared. High temperature stability (up to 300 deg C) of piezoelectric properties and elastic ductibility is characteristic of the investigated system. Introduction of barium, sodium metaniobates and lead titanate in lead metaniobate ceramics permits to prepare piezomaterials both with high (Qsub(m)=300-350) and with low (Qsub(m)=20) mechanical quality factor.

  3. Structure and thermodynamics of Cr-Fe hydroxide solid solutions

    Science.gov (United States)

    Guo, X.; Daemen, L.; Liu, N.; Wu, D.; Boukhalfa, H.; Migdissov, A. A.; Sun, C.; Navrotsky, A.; Roback, R. C.; Reimus, P. W.; Xu, H.

    2016-12-01

    Cr(VI) in the form of CrO42- is a pollutant species in soils and groundwater that poses health and environmental issues. Natural remediation processes include reduction of Cr(VI) to Cr(III). Via electron exchange with naturally abundant Fe-bearing minerals, which leads to the formation of Cr(III)-Fe(III) hydroxides. Because these phases are largely X-ray amorphous, their structural characteristics have not been well determined. In this work, we synthesized five samples with different Fe/Cr ratios, and we used synchrotron X-rays to obtain high-resolution diffraction (XRD) and absorption spectroscopy (XAS) data to study both their long range and local structural characteristics. In addition, infrared spectroscopy was conducted to obtain OH bonding information. Our results indicate that the crystallinity of these samples decreases systematically with increasing Fe/Cr ratio and that the Fe-rich samples may contain oxyhydroxides. Thermogravimetry (TG) and differential scanning calorimetry (DSC) coupled with mass spectrometry (MS) data indicate that these oxyhydrides contain about 15 - 33 wt. % water/OH- and a water contents decrease with increasing Fe/Cr ratio. Finally, the enthalpies of formation of this solid solution are all endothermic, suggesting the instability of these hydroxides relative to their corresponding oxides. These comprehensive structural and thermodynamic analyses yield fundamental parameters for understanding the behavior of Cr-Fe hydroxides/oxyhydroxides in the environment.

  4. (1-xPux)Sb solid solutions. 1. Magnetic configurations

    DEFF Research Database (Denmark)

    Normile, P.S.; Stirling, W.G.; Mannix, D.

    2002-01-01

    , the correlation length is even shorter. The observation of a second-order resonance harmonic is linked to the multi-k nature of the configurations, and its unusual temperature dependence is explained by using the phase diagram established for the x=0.75 sample by neutron diffraction. We conclude with a discussion......Neutron and resonant x-ray magnetic scattering studies have been performed on single crystals of three compositions, x=0.25, 0.50, and 0.75 of the (U1-xPux)Sb solid solution. Neutron diffraction has established the ordering wave vector (k=1 for x=0.25 and 0.50, as in x=0, USb, and k=0.25 for x=0.......75), the average magnetic moment, and the temperature dependence of the magnetic order. For the x=0.75 sample the presence of a third-order harmonic indicates a substantial squaring of the 4+, 4- magnetic configuration. Experiments with a field applied to the sample have shown that the x=0.25 and 0.50 samples...

  5. Quantum Critical Behavior in a Concentrated Ternary Solid Solution.

    Science.gov (United States)

    Sales, Brian C; Jin, Ke; Bei, Hongbin; Stocks, G Malcolm; Samolyuk, German D; May, Andrew F; McGuire, Michael A

    2016-05-18

    The face centered cubic (fcc) alloy NiCoCrx with x ≈ 1 is found to be close to the Cr concentration where the ferromagnetic transition temperature, Tc, goes to 0. Near this composition these alloys exhibit a resistivity linear in temperature to 2 K, a linear magnetoresistance, an excess -TlnT (or power law) contribution to the low temperature heat capacity, and excess low temperature entropy. All of the low temperature electrical, magnetic and thermodynamic properties of the alloys with compositions near x ≈ 1 are not typical of a Fermi liquid and suggest strong magnetic fluctuations associated with a quantum critical region. The limit of extreme chemical disorder in this simple fcc material thus provides a novel and unique platform to study quantum critical behavior in a highly tunable system.

  6. Machine learning assisted first-principles calculation of multicomponent solid solutions: estimation of interface energy in Ni-based superalloys

    Science.gov (United States)

    Chandran, Mahesh; Lee, S. C.; Shim, Jae-Hyeok

    2018-02-01

    A disordered configuration of atoms in a multicomponent solid solution presents a computational challenge for first-principles calculations using density functional theory (DFT). The challenge is in identifying the few probable (low energy) configurations from a large configurational space before DFT calculation can be performed. The search for these probable configurations is possible if the configurational energy E({\\boldsymbol{σ }}) can be calculated accurately and rapidly (with a negligibly small computational cost). In this paper, we demonstrate such a possibility by constructing a machine learning (ML) model for E({\\boldsymbol{σ }}) trained with DFT-calculated energies. The feature vector for the ML model is formed by concatenating histograms of pair and triplet (only equilateral triangle) correlation functions, {g}(2)(r) and {g}(3)(r,r,r), respectively. These functions are a quantitative ‘fingerprint’ of the spatial arrangement of atoms, familiar in the field of amorphous materials and liquids. The ML model is used to generate an accurate distribution P(E({\\boldsymbol{σ }})) by rapidly spanning a large number of configurations. The P(E) contains full configurational information of the solid solution and can be selectively sampled to choose a few configurations for targeted DFT calculations. This new framework is employed to estimate (100) interface energy ({σ }{{IE}}) between γ and γ \\prime at 700 °C in Alloy 617, a Ni-based superalloy, with composition reduced to five components. The estimated {σ }{{IE}} ≈ 25.95 mJ m‑2 is in good agreement with the value inferred by the precipitation model fit to experimental data. The proposed new ML-based ab initio framework can be applied to calculate the parameters and properties of alloys with any number of components, thus widening the reach of first-principles calculation to realistic compositions of industrially relevant materials and alloys.

  7. Application of the cluster variation method to interstitial solid solutions

    NARCIS (Netherlands)

    Pekelharing, M.I.

    2008-01-01

    A thermodynamic model for interstitial alloys, based on the Cluster Variation Method (CVM), has been developed, capable of incorporating short range ordering (SRO), long range ordering (LRO), and the mutual interaction between the host and the interstitial sublattices. The obtained cluster-based

  8. Cluster Variation Study of Ordering in FCC Solid Solutions.

    Science.gov (United States)

    1980-07-01

    34, Annual Meeting Sociedade Brasileira de Cristalografia, Recife, Brazil, July 18-21, 1979. Sanchez, J. M., "The Cluster Variation Method", Centro... Universidade de Slo Paulo, Brazil, October 29, 1979. de Fontaine, D., "Prediction of Coherent Phase Equilibria in Alloys", School of Eng. Appl. Sc

  9. Local structure in the disordered solid solution of cis- and trans-perinones

    DEFF Research Database (Denmark)

    Teteruk, Jaroslav L.; Glinnemann, Juergen; Heyse, Winfried

    2016-01-01

    The cis- and trans-isomers of the polycyclic aromatic compound perinone, C26H12N4O2, form a solid solution (Vat Red 14). This solid solution is isotypic to the crystal structures of cis-perinone (Pigment Red 194) and trans-perinone (Pigment Orange 34) and exhibits a combined positional...

  10. Preparation and characterization of barium titanate stannate solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Horchidan, Nadejda, E-mail: NHorchidan@stoner.phys.uaic.ro [Department of Physics, ' Al. I. Cuza' University, Bv. Carol 11, Iasi 700506 (Romania); Ianculescu, Adelina C. [Department of Oxide Materials Science and Engineering, Polytechnics University, 1-7 Gh. Polizu, P.O. Box 12-134, 011061 Bucharest (Romania); Curecheriu, Lavinia P.; Tudorache, Florin [Department of Physics, ' Al. I. Cuza' University, Bv. Carol 11, Iasi 700506 (Romania); Musteata, Valentina [Institute of Macromolecular Chemistry ' Petru Poni' , Aleea Grigore Ghica Voda 41A, 700487 Iasi (Romania); Stoleriu, Stefania [Department of Oxide Materials Science and Engineering, Polytechnics University, 1-7 Gh. Polizu, P.O. Box 12-134, 011061 Bucharest (Romania); Dragan, Nicolae; Crisan, Dorel [Institute of Physical Chemistry ' Ilie Murgulescu' , Lab. of Oxide Materials Science, 202 Splaiul Independentei, 060021 Bucharest (Romania); Tascu, Sorin; Mitoseriu, Liliana [Department of Physics, ' Al. I. Cuza' University, Bv. Carol 11, Iasi 700506 (Romania)

    2011-04-07

    Research highlights: > BaSnxTi1-xO3 (x = 0; 0.05; 0.1; 0.15; 0.2) ceramics were prepared by solid state reaction and sintered at 13000C for 4h. > The phase purity, structural parameters and microstructural characteristics were investigated. > The dielectric properties were studied as function of temperature and frequency and empirical parameters {eta} and {delta} were calcutate. > The non-linear dielectric properties (tunability) of the samples were studied at room temperature. > By increasing the Sn addition, the {epsilon}(E) dependence tends to reduce its hysteresis behaviour. - Abstract: BaSn{sub x}Ti{sub 1-x}O{sub 3} (x = 0; 0.05; 0.1; 0.15; 0.2) solid solutions were prepared via conventional solid state reaction and sintered at 1300 {sup o}C for 4 h, resulting in dense single phase ceramics with homogeneous microstructures. Tetragonal symmetry for x {<=} 0.1, cubic for x = 0.2 and a superposition of tetragonal and cubic for x = 0.15 compositions were found by X-ray diffraction analysis. The temperature and frequency dependence of the complex dielectric constant and dc tunability were determined. A transformation from normal ferroelectric to relaxor with diffuse phase transition was observed with increasing the Sn concentration. All the investigated compositions show a relative tunability between 0.55 (for x = 0.2) and 0.74 (for x = 0.1), at a field amplitude of E = 20 kV/cm.

  11. Hydrogen storage and stability properties of Pd-Pt solid-solution nanoparticles revealed via atomic and electronic structure.

    Science.gov (United States)

    Kumara, Loku Singgappulige Rosantha; Sakata, Osami; Kobayashi, Hirokazu; Song, Chulho; Kohara, Shinji; Ina, Toshiaki; Yoshimoto, Toshiki; Yoshioka, Satoru; Matsumura, Syo; Kitagawa, Hiroshi

    2017-11-06

    Bimetallic Pd1-x Pt x solid-solution nanoparticles (NPs) display charging/discharging of hydrogen gas, which has relevance for fuel cell technologies; however, the constituent elements are immiscible in the bulk phase. We examined these material systems using high-energy synchrotron X-ray diffraction, X-ray absorption fine structure and hard X-ray photoelectron spectroscopy techniques. Recent studies have demonstrated the hydrogen storage properties and catalytic activities of Pd-Pt alloys; however, comprehensive details of their structural and electronic functionality at the atomic scale have yet to be reported. Three-dimensional atomic-scale structure results obtained from the pair distribution function (PDF) and reverse Monte Carlo (RMC) methods suggest the formation of a highly disordered structure with a high cavity-volume-fraction for low-Pt content NPs. The NP conduction band features, as extracted from X-ray absorption near-edge spectra at the Pd and Pt L III -edge, suggest that the Pd conduction band is filled by Pt valence electrons. This behaviour is consistent with observations of the hydrogen storage capacity of these NPs. The broadening of the valence band width and the down-shift of the d-band centre away from the Fermi level upon Pt substitution also provided evidence for enhanced stability of the hydride (ΔH) features of the Pd1-x Pt x solid-solution NPs with a Pt content of 8-21 atomic percent.

  12. Thermodynamic study of solid solutions in the SnTe-AgSbTe2 system by means of EMF with solid electrolyte Ag4RbI5

    Science.gov (United States)

    Mashadieva, L. F.; Yusibov, Yu. A.; Kevser, Dzh.; Babanly, M. B.

    2017-09-01

    The results from studying the SnTe-AgSbTe2 system by means of EMF with the solid electrolyte Ag4RbI5 in the temperature range of 300-430 K are presented. The formation of a wide (≥80 mol % of AgSbTe2) region of solid solutions based on SnTe is confirmed. Partial thermodynamic functions Δ G̅, Δ H̅, and Δ S̅ of silver in alloys are calculated from the equations for the EMF temperature dependences. Based on the literature data regarding solid-phase equilibria in the Ag2Te-SnTe-Sb2Te3-Te system, potential-determining reactions are identified that allow us to calculate the standard thermodynamic formation functions and standard entropies of solid solutions (2SnTe) x (AgSbTe2)1- x ( x = 0.2, 0.4, 0.6, 0.8, and 0.9).

  13. Nanometric solid solutions of the fluorite and perovskite type crystal structures: Synthesis and properties

    Directory of Open Access Journals (Sweden)

    Snežana Bošković

    2012-09-01

    Full Text Available In this paper a short review of our results on the synthesis of nanosized CeO2, CaMnO3 and BaCeO3 solid solutions are presented. The nanopowders were prepared by two innovative methods: self propagating room temperature synthesis (SPRT and modified glycine/nitrate procedure (MGNP. Different types of solid solutions with rare earth dopants in concentrations ranging from 0–0.25 mol% were synthesized. The reactions forming solid solutions were studied. In addition, the characteristics of prepared nanopowders, phenomena during sintering and the properties of sintered samples are discussed.

  14. Study of reaction sequences for formation of solid solution: 0,48 ...

    African Journals Online (AJOL)

    To study the reaction sequences of formation of solid solution zirconate-lead titanate (PZT) in this work, we took into account the effect of adding oxide dopants on the progress of the reaction, so we added oxides ZnO, Cr2O3, Sb2O3 to our material composition in small quantities so that the solid solution must verify the ...

  15. Influence of Ce 0.68 Zr 0.32 O 2 solid solution on depositing ...

    Indian Academy of Sciences (India)

    The results show that the addition of Ce0.68Zr0.32O2 solid solution into slurries can improve -Al2O3-based washcoat adhesion on FeCrAl foils. The more the Ce0.68Zr0.32O2 solid solution added into slurries, the higher was the specific surface area of aged samples. XRD characterization proved that ceria–zirconia solid ...

  16. High pressure x-ray diffraction study of nickel-copper chromites solid solutions

    Science.gov (United States)

    Mikheykin, A. S.; Torgashev, V. I.; Talanov, V. M.; Bush, A. A.; Chernyshov, D.; Yuzyuk, I. Yu; Dmitriev, V. P.

    2014-12-01

    A high-pressure synchrotron radiation diffraction study has been carried out on Ni1-xCuxCr2O4 solid solutions. Observed pressure-controlled phase transitions, along with data previously collected for temperature-induced phase transitions, are analyzed in the framework of the unified phenomenological model that results in mapping of the generic phase diagram for the whole family of Ni1-xCuxCr2O4 solid solutions.

  17. Precipitation in solid solution and structural transformations in single crystals of high rhenium ruthenium-containing nickel superalloys at high-temperature creep

    Energy Technology Data Exchange (ETDEWEB)

    Alekseev, A.A.; Petrushin, N.V.; Zaitsev, D.V.; Treninkov, I.A.; Filonova, E.V. [All-Russian Scientific Research Institute of Aviation Materials (VIAM), Moscow (Russian Federation)

    2010-07-01

    The phase composition and structure of single crystals of two superalloys (alloy 1 and alloy 2) were investigated in this work. For alloy 1 (Re - 9 wt%) the kinetics of precipitation in solid solution at heat treatment (HT) was investigated. TEM and X-Ray examinations have revealed that during HT rhombic phase (R-phase) precipitation (Immm class (BCR)) occurs. The TTT diagram is plotted, it contains the time-temperature area of the existence of R-phase particles. The element content of R-phase is identified (at. %): Re- 51.5; Co- 23.5; Cr- 14.8; Mo- 4.2; W- 3.3; Ta- 2.7. For alloy 2 (Re - 6.5 wt %, Ru - 4 wt %) structural transformations at high-temperature creep are investigated. By dark-field TEM methods it is established, that in alloy 2 the additional phase with a rhombic lattice is formed during creep. Particles of this phase precipitate in {gamma}-phase and their quantity increases during high-temperature creep. It is revealed that during creep 3-D dislocation network is formed in {gamma}-phase. At the third stage of creep the process of inversion structure formation is observed in the alloy, i.e. {gamma}'-phase becomes a matrix. Thus during modeling creep the volume fraction of {gamma}'-phase in the samples increases from 30% (at creep duration of 200 hrs) up to 55% (at 500 hrs). The processes of structure formation in Re and Ru-containing nickel superalloys are strongly affected by decomposition of solid solution during high-temperature creep that includes precipitation of additional TCP-phases. (orig.)

  18. Solid state synthesis, crystal growth and optical properties of urea and p-chloronitrobenzene solid solution

    Energy Technology Data Exchange (ETDEWEB)

    Rai, R.N., E-mail: rn_rai@yahoo.co.in [Department of Chemistry, Centre of Advanced Study, Banaras Hindu University, Varanasi 221005 (India); Kant, Shiva; Reddi, R.S.B. [Department of Chemistry, Centre of Advanced Study, Banaras Hindu University, Varanasi 221005 (India); Ganesamoorthy, S. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamilnadu (India); Gupta, P.K. [Laser Materials Development & Devices Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)

    2016-01-15

    Urea is an attractive material for frequency conversion of high power lasers to UV (for wavelength down to 190 nm), but its usage is hindered due to its hygroscopic nature, though there is no alternative organic NLO crystal which could be transparent up to 190 nm. The hygroscopic character of urea has been modified by making the solid solution (UCNB) of urea (U) and p-chloronitrobenzene (CNB). The formation of the solid solution of CNB in U is explained on the basis of phase diagram, powder XRD, FTIR, elemental analysis and single crystal XRD studies. The solubility of U, CNB and UCNB in ethanol solution is evaluated at different temperatures. Transparent single crystals of UCNB are grown from its saturated solution in ethanol. Optical properties e.g., second harmonic generation (SHG), refractive index and the band gap for UCNB crystal were measured and their values were compared with the parent compounds. Besides modification in hygroscopic nature, UCNB has also shown the higher SHG signal and mechanical hardness in comparison to urea crystal. - Highlights: • The hygroscopic character of urea was modified by making the solid solutionSolid solution formation is support by elemental, powder- and single crystal XRD • Crystal of solid solution has higher SHG signal and mechanical stability. • Refractive index and band gap of solid solution crystal have determined.

  19. Computer simulation of disordered compounds and solid solutions

    CERN Document Server

    Pongsai, B

    2001-01-01

    simulations have also been carried out for comparison. Atomistic simulations (QLD and MCX) with full relaxation predict DELTA H sub m sub i sub x values that are less negative than those from the HF calculations in the static limit. The phase diagram is also calculated from the MCX calculations, indicating complete miscibility at temperatures as low as 200 K. In Chapter 5, both QLD and MCX methods are used to investigate the disordered metallic alloy Pd-Rh. At 300 K, vibrational contributions contribute significantly to the entropy, but not the enthalpy of mixing. The calculated consolute temperature is just above 1200 K in good agreement with experiment. In Chapter 6, we apply our new technique to the order-disorder phase transition of a complex oxygen-deficient perovskite Sr sub 2 Fe sub 2 O sub 5. The calculated order-disorder phase transition occurs between 700 and 930 K, in good agreement with experiment. Investigation of individual configurations shows the coexistence of four-, five- and six-coordinated...

  20. A Unified Physical Model for Creep and Hot Working of Al-Mg Solid Solution Alloys

    OpenAIRE

    Stefano Spigarelli; Chiara Paoletti

    2017-01-01

    The description of the dependence of steady-state creep rate on applied stress and temperature is almost invariably based on the Norton equation or on derived power-law relationships. In hot working, the Norton equation does not work, and is therefore usually replaced with the Garofalo (sinh) equation. Both of these equations are phenomenological in nature and can be seldom unambiguously related to microstructural parameters, such as dislocation density, although early efforts in this sense l...

  1. Computing phase relations involving ordered solid solutions ab initio: Three thermodynamic approaches to the Fe-Si binary

    Science.gov (United States)

    Asimow, P. D.; Caracas, R.; Wolf, A. S.; Harvey, J. P.

    2016-12-01

    To find inner core compositions (X) consistent with geophysical data, we need phase relations of multicomponent metallic systems at high pressure (P) and temperature (T); the stable phase at a given (P,T,X) determines the physical properties. Given the difficulty of experiments under inner core conditions, reliable computations of such phase relations are needed. Despite advances in computational methods and computing power, challenges include proper treatment of solid solutions with their continuous variation in composition and ordering phenomena. We consider here how to predict phase diagrams from thermodynamic models of partly ordered solid solution phases calibrated with density functional theory to obtain static enthalpy (H) and volume (V), density functional perturbation theory and quasiharmonic approximation for vibrational heat capacity, and three approaches to solution theory to parameterize mixing properties. This approach is applied to B2 and HCP structures in the system Fe-FeSi for comparison to experimental data such as Fischer et al. (2013). We computed H and V of 7 compositions across the Fe-FeSi binary for both B2 and HCP structures, every 20 or 40 GPa from 0 to 400 GPa. We used supercells with up to 24 atoms to explore multiple configurations of the atoms. The H differences among clustered, random, and ordered arrangments of the atoms are neither so small as to imply random mixing nor so large that one configuration will dominate. We computed phonon density of states of at least three compositions for each structure in order to define vibrational heat capacity across each binary using ideal mixing and to test this approximation. We then used three different approaches to solid solution theory to fit the mixing properties: (1) Asymmetric regular solution theory, with (P,T)-dependent Margules parameters to describe the excess H but assuming ideal one-site entropy (S) of mixing; (2) the quasichemical model, accounting for optimized Fe-Si pair

  2. Positron annihilation studies in binary solid solutions and mechanical mixtures of lanthanide dipivaloylmethanate complexes

    Energy Technology Data Exchange (ETDEWEB)

    Fulgêncio, F., E-mail: fefulgencio@gmail.com [Departamento de Química, ICEx, Universidade Federal de Minas Gerais – UFMG, C.P. 702, CEP 31270-901 – Belo Horizonte, MG (Brazil); Oliveira, F.C. [Grupo de Pesquisa em Nanociências e Nanomateriais, Centro Federal de Educação Tecnológica de Minas Gerais (CEFET-MG), Campus Timóteo, Timóteo, MG (Brazil); Windmöller, D.; Araujo, M.H.; Marques-Netto, A.; Machado, J.C. [Departamento de Química, ICEx, Universidade Federal de Minas Gerais – UFMG, C.P. 702, CEP 31270-901 – Belo Horizonte, MG (Brazil); Magalhães, W.F., E-mail: welmag@ufmg.br [Departamento de Química, ICEx, Universidade Federal de Minas Gerais – UFMG, C.P. 702, CEP 31270-901 – Belo Horizonte, MG (Brazil)

    2015-11-05

    Highlights: • Positronium formation in several Ln{sup 3+} complexes, except in Eu{sup 3+} complexes. • Positron annihilation spectroscopies used as a characterization tool of solid solutions and mechanical mixtures. • Measurements performed at different temperatures (80 and 295 K). - Abstract: Measurements using positron annihilation lifetime (PALS) and Doppler broadening annihilation radiation lineshape (DBARLS) spectroscopies were performed in several lanthanide dipivaloylmethanate complexes, Ln(dpm){sub 3} where Ln = Sm{sup 3+}, Gd{sup 3+}, Tb{sup 3+}, Ho{sup 3+}, Er{sup 3+}, Yb{sup 3+} and dpm = 2,2,6,6-tetramethyl-3,5-pentanedionate, and also on their binary solid solutions and mechanical mixtures, biphasic systems, of the general formula Ln{sub 1−x}Eu{sub x}(dpm){sub 3}. Expressive positronium formation was observed in all Ln(dpm){sub 3} complexes, except in Eu(dpm){sub 3} complex. The results indicate formation of solid solutions in the Sm{sup 3+}, Gd{sup 3+}and Tb{sup 3+} systems, where total inhibition of positronium formation was observed. A Stern–Volmer type equation, I{sub 3}{sup 0}/I{sub 3} = 1 + kx, was used to fit the data, enabling the calculation of the inhibition constants, k. A mechanical mixture behavior, with linear variation of I{sub 3} between the I{sub 3} values of the pure complexes, was observed in systems containing Ho{sup 3+}, Er{sup 3+} and Yb{sup 3+} complexes, where no effective solid solution formation occurred due to differences between the crystalline structures of these complexes and Eu(dpm){sub 3}. No positronium quenching reactions were observed in the solid solutions. DBARLS results confirmed those of PALS, evidencing that the positron annihilation spectroscopies are useful techniques to characterize the formation of solid solutions. PALS measurements at 80 K were performed in the Sm{sub 1−x}Eu{sub x}(dpm){sub 3} and Gd{sub 1−x}Eu{sub x}(dpm){sub 3} solid solutions. The results indicate that, despite a contraction

  3. Active Edge Sites Engineering in Nickel Cobalt Selenide Solid Solutions for Highly Efficient Hydrogen Evolution

    KAUST Repository

    Xia, Chuan

    2017-01-06

    An effective multifaceted strategy is demonstrated to increase active edge site concentration in NiCoSe solid solutions prepared by in situ selenization process of nickel cobalt precursor. The simultaneous control of surface, phase, and morphology result in as-prepared ternary solid solution with extremely high electrochemically active surface area (C = 197 mF cm), suggesting significant exposure of active sites in this ternary compound. Coupled with metallic-like electrical conductivity and lower free energy for atomic hydrogen adsorption in NiCoSe, identified by temperature-dependent conductivities and density functional theory calculations, the authors have achieved unprecedented fast hydrogen evolution kinetics, approaching that of Pt. Specifically, the NiCoSe solid solutions show a low overpotential of 65 mV at -10 mV cm, with onset potential of mere 18 mV, an impressive small Tafel slope of 35 mV dec, and a large exchange current density of 184 μA cm in acidic electrolyte. Further, it is shown that the as-prepared NiCoSe solid solution not only works very well in acidic electrolyte but also delivers exceptional hydrogen evolution reaction (HER) performance in alkaline media. The outstanding HER performance makes this solid solution a promising candidate for mass hydrogen production.

  4. Progress in High-Entropy Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Michael C

    2013-12-01

    Strictly speaking, high-entropy alloys (HEAs) refer to single-phase, solid-solution alloys with multiprincipal elements in an equal or a near-equal molar ratio whose configurational entropy is tremendously high. This special topic was organized to reflect the focus and diversity of HEA research topics in the community.

  5. The effect of alloying additives on structure and properties of cast Al-Cu-Si-Mg alloys

    Energy Technology Data Exchange (ETDEWEB)

    Eskin, D.G. [Russian Academy of Sciences, Moscow (Russian Federation). Baikov Inst. of Metall.

    1995-01-01

    The effect of base and additive alloying elements on the structure and properties of cast Al-Cu-Si-Mg alloys was studied. The mechanical properties at room and elevated temperatures were shown to correlate well with the composition of a supersaturated solid solution and the structure of cast alloys. (orig.)

  6. Rhenium alloying of tungsten heavy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bose, A.; Jerman, G.; German, R.M.

    1989-06-01

    Alloying experiments have been performed using rhenium additions to a classic 90 mass% tungsten heavy alloy. The mixed powder system was liquid phase sintered to full density at 1500/sup 0/C in 60 min. The rhenium modified alloys exhibited a smaller grain size, higher hardness, higher strength, and lower ductility than the unalloyed system. For an alloy with a composition of 84W-6Re-8Ni-2Fe, the sintered density was 17,4 Mg/m/sup 3/ with a yield strength of 815 MPa, tensile strength of 1180 MPa, and elongation to failure of 13%. This property combination results from the aggregate effects of grain size reduction and solid solution hardening due to rhenium. In the unalloyed system these properties require post-sintering swaging and aging; thus, alloying with rhenium is most attractive for applications where netshaping is desired, such as by powder injection molding. (orig.).

  7. Rhenium alloying of tungsten heavy alloys

    Energy Technology Data Exchange (ETDEWEB)

    German, R.M.; Bose, A.; Jerman, G.

    1989-01-01

    Alloying experiments were performed using rhenium additions to a classic 90 mass % tungsten heavy alloy. The mixed-powder system was liquid phase sintered to full density at 1500 C in 60 min The rhenium-modified alloys exhibited a smaller grain size, higher hardness, higher strength, and lower ductility than the unalloyed system. For an alloy with a composition of 84W-6Re-8Ni-2Fe, the sintered density was 17, 4 Mg/m{sup 3} with a yield strength of 815 MPa, tensile strength of 1180 MPa, and elongation to failure of 13%. This property combination results from the aggregate effects of grain size reduction and solid solution hardening due to rhenium. In the unalloyed system these properties require post-sintering swaging and aging; thus, alloying with rhenium is most attractive for applications where net shaping is desired, such as by powder injection molding.

  8. Phase coexistence in ferroelectric solid solutions: Formation of monoclinic phase with enhanced piezoelectricity

    Directory of Open Access Journals (Sweden)

    Xiaoyan Lu

    2016-10-01

    Full Text Available Phase morphology and corresponding piezoelectricity in ferroelectric solid solutions were studied by using a phenomenological theory with the consideration of phase coexistence. Results have shown that phases with similar energy potentials can coexist, thus induce interfacial stresses which lead to the formation of adaptive monoclinic phases. A new tetragonal-like monoclinic to rhombohedral-like monoclinic phase transition was predicted in a shear stress state. Enhanced piezoelectricity can be achieved by manipulating the stress state close to a critical stress field. Phase coexistence is universal in ferroelectric solid solutions and may provide a way to optimize ultra-fine structures and proper stress states to achieve ultrahigh piezoelectricity.

  9. Session 4: Solid solution sulfide photo-catalysts for hydrogen evolution under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Tsuji, I.; Kato, H. [Tokyo Univ., Faculty of Science, Dept. of Applied Chemistry (Japan); Kudo, A.; Kobayashi, H. [Kurashiki Univ. of Science and the Arts, (Japan); Kudo, A. [Japan Science and Technology Agency, Core Research for Evolutional Science and Technology (Japan)

    2004-07-01

    In the present study, we tried to make a new visible-light driven photo-catalyst for H{sub 2} evolution by making solid solutions between ZnS photo-catalyst with a wide band gap, and AgInS{sub 2} and CuInS{sub 2} with narrow band gaps. The photophysical and photo-catalytic properties of (MIn){sub x}Zn{sub 2(1-x)}S{sub 2} (M=Cu, Ag) solid solutions were investigated. (authors)

  10. Synthesis and Non-isothermal Carbothermic Reduction of FeTiO3-Fe2O3 Solid Solution Systems

    Science.gov (United States)

    Liu, Yiran; Zhang, Jianliang; Xing, Xiangdong; Liu, Zhengjian; Liu, Xingle; Li, Naiyao; Shen, Yansong

    2017-10-01

    To investigate the carbothermic reduction behaviors of xFeTiO3·(1 - x)Fe2O3 solid solutions, the solid solutions with different x values were synthesized and used in the corresponding reactions. With an increase in x, the temperature pertaining to the onset of carbothermic reduction increased, while the rate of reduction of the solid solutions, α, decreased. The lattice parameters calculated from XRD patterns indicated that the solid solution with a higher x led to a larger lattice distortion. The non-isothermal kinetics were calculated, and an average activation energy E value of 3.0 × 102 kJ/mol was obtained.

  11. Prediction of solid solution formation in a family of diastereomeric salts. A molecular modeling study

    NARCIS (Netherlands)

    Gervais, C.; Grimbergen, R.F.P.; Markovits, I.; Ariaans, G.J.A.; Kaptein, B.; Bruggink, A.; Broxterman, Q.B.

    2004-01-01

    The possibility of solid solution behavior of diastereomeric salts, containing multiple resolving agents of the same family (Dutch Resolution), is predicted by molecular modeling. Super-cells containing different ratios of resolving agents in the diastereomeric salt are constructed and optimized,

  12. Bridging phases at the morphotropic boundaries of lead oxide solid solutions

    NARCIS (Netherlands)

    Noheda, Beatriz; Cox, DE

    2006-01-01

    Ceramic solid solutions of PbZr1-xTixO3 (PZT) with compositions x similar or equal to 0.50 are well-known for their extraordinarily large piezoelectric responses. The latter are highly anisotropic, and it was recently shown that, for the rhombohedral compositions (x less than or similar to 0.5), the

  13. Structural investigations of (La,Pu)PO4 monazite solid solutions: XRD and XAFS study

    Science.gov (United States)

    Arinicheva, Yulia; Popa, Karin; Scheinost, Andreas C.; Rossberg, André; Dieste-Blanco, Oliver; Raison, Philippe; Cambriani, Andrea; Somers, Joseph; Bosbach, Dirk; Neumeier, Stefan

    2017-09-01

    A solid state method was used to synthesize La1-xPuxPO4 (x = 0.01, 0.05, 0.10, 0.15, (0.5)) solid solutions with monazite structure. XRD measurements of the compounds with x = 0.50 revealed the formation of two phases: (La,Pu)PO4-monazite and a cubic phase (PuO2). Pure-phase La1-xPuxPO4-monazite solid solutions were obtained for materials with x = 0.00-0.15 and confirmed by a linear dependence of the lattice parameters on composition according to Vegard's law. X-ray absorption spectroscopy (XAS) analysis at the Pu-LIII and La-LIII edges confirmed the +III valence state of plutonium in the monazite solid solutions. The local environment of Pu is PuPO4-like along the solid solution series, except for the longest fitted cation-cation distance, which may be an indication of cluster formation consisting of a few Pu-atoms in the La-Pu-monazite lattice.

  14. Defect structure of cubic solid solutions of alkaline earth and rare earth fluorides

    NARCIS (Netherlands)

    DenHartog, HW

    1996-01-01

    In this paper we will consider the disorder in some cubic solid solutions consisting of one of the alkaline earth fluorides and one of the rare earth fluorides. This is an attractive group of model materials, because these materials have a rather simple overall cubic structure. We will discuss the

  15. Interdiffusion and impurity diffusion in polycrystalline Mg solid solution with Al or Zn

    Energy Technology Data Exchange (ETDEWEB)

    Kammerer, C.C. [University of Central Florida, Advanced Materials Processing and Analysis Center, Department of Materials Science and Engineering, Orlando, FL 32816 (United States); Kulkarni, N.S. [Knoxville, Tennessee 37931 (United States); Warmack, R.J. [Oak Ridge National Laboratory, Measurement Science and Systems Engineering Division, Oak Ridge, TN 37831 (United States); Sohn, Y.H. [University of Central Florida, Advanced Materials Processing and Analysis Center, Department of Materials Science and Engineering, Orlando, FL 32816 (United States)

    2014-12-25

    Highlights: • Interdiffusion coefficients within Mg(Al) and Mg(Zn) solid solutions. • Impurity diffusion of Al and Zn in Mg. • Interdiffusion coefficient in Mg(Zn) was higher than that of Mg(Al). • Zn impurity diffusion coefficient was higher than that of Al in Mg. - Abstract: Interdiffusion and impurity diffusion in Mg binary solid solutions, Mg(Al) and Mg(Zn) were investigated at temperatures ranging from 623 to 723 K. Interdiffusion coefficients were determined via the Boltzmann–Matano Method using solid-to-solid diffusion couples assembled with polycrystalline Mg and Mg(Al) or Mg(Zn) solid solutions. In addition, the Hall method was employed to extrapolate the impurity diffusion coefficients of Al and Zn in pure polycrystalline Mg. For all diffusion couples, electron microprobe analysis was utilized for the measurement of concentration profiles. The interdiffusion coefficient in Mg(Zn) was higher than that of Mg(Al) by an order of magnitude. Additionally, the interdiffusion coefficient increased significantly as a function of Al content in Mg(Al) solid solution, but very little with Zn content in Mg(Zn) solid solution. The activation energy and pre-exponential factor for the average effective interdiffusion coefficient in Mg(Al) solid solution were determined to be 186.8 (±0.9) kJ/mol and 7.69 × 10{sup −1} (±1.80 × 10{sup −1}) m{sup 2}/s, respectively, while those determined for Mg(Zn) solid solution were 139.5 (±4.0) kJ/mol and 1.48 × 10{sup −3} (±1.13 × 10{sup −3}) m{sup 2}/s. In Mg, the Zn impurity diffusion coefficient was an order of magnitude higher than the Al impurity diffusion coefficient. The activation energy and pre-exponential factor for diffusion of Al impurity in Mg were determined to be 139.3 (±14.8) kJ/mol and 6.25 × 10{sup −5} (±5.37 × 10{sup −4}) m{sup 2}/s, respectively, while those for diffusion of Zn impurity in Mg were determined to be 118.6 (±6.3) kJ/mol and 2.90 × 10{sup −5} (±4.41 × 10{sup −5

  16. Separating the strengthening phase in nickel-cobalt alloys doped with tantalum

    Science.gov (United States)

    Shaipov, R. Kh.; Kerimov, E. Yu.; Slyusarenko, E. M.

    2017-02-01

    The hardness values of monophasic (fcc solid solution) and biphasic (fcc solid solution and separated phase) nickel-cobalt alloys doped with tantalum are determined using the Vickers method. Based on the resulting data, a composition-structure-hardness diagram is devised for the Co-Ni-Ta system.

  17. First-principles investigation of competing magnetic interactions in (Mn ,Fe )Ru2Sn Heusler solid solutions

    Science.gov (United States)

    Decolvenaere, Elizabeth; Gordon, Michael; Seshadri, Ram; Van der Ven, Anton

    2017-10-01

    Many Heusler compounds possess magnetic properties well suited for applications as spintronic materials. The pseudobinary Mn0.5Fe0.5Ru2Sn , formed as a solid solution of two full Heuslers, has recently been shown to exhibit exchange hardening suggestive of two magnetic phases, despite existing as a single chemical phase. We have performed a first-principles study of the chemical and magnetic degrees of freedom in the Mn1 -xFexRu2Sn pseudobinary to determine the origin of the unique magnetic behavior responsible for exchange hardening within a single phase. We find a transition from antiferromagnetic (AFM) to ferromagnetic (FM) behavior upon replacement of Mn with Fe, consistent with experimental results. The lowest energy orderings in Mn1 -xFexRu2Sn consist of chemically and magnetically uniform (111) planes, with Fe-rich regions preferring FM ordering and Mn-rich regions preferring AFM ordering, independent of the overall composition. Analysis of the electronic structure suggests that the magnetic behavior of this alloy arises from a competition between AFM-favoring Sn-mediated superexchange and FM-favoring RKKY exchange mediated by spin-polarized conduction electrons. Changes in valency upon replacement of Mn with Fe shifts the balance from superexchange-dominated interactions to RKKY-dominated interactions.

  18. Thermal Analysis of Tantalum Carbide-Hafnium Carbide Solid Solutions from Room Temperature to 1400 °C

    Directory of Open Access Journals (Sweden)

    Cheng Zhang

    2017-07-01

    Full Text Available The thermogravimetric analysis on TaC, HfC, and their solid solutions has been carried out in air up to 1400 °C. Three solid solution compositions have been chosen: 80TaC-20 vol % HfC (T80H20, 50TaC-50 vol % HfC (T50H50, and 20TaC-80 vol % HfC (T20H80, in addition to pure TaC and HfC. Solid solutions exhibit better oxidation resistance than the pure carbides. The onset of oxidation is delayed in solid solutions from 750 °C for pure TaC, to 940 °C for the T50H50 sample. Moreover, T50H50 samples display the highest resistance to oxidation with the retention of the initial carbides. The oxide scale formed on the T50H50 sample displays mechanical integrity to prevent the oxidation of the underlying carbide solid solution. The improved oxidation resistance of the solid solution is attributed to the reaction between Ta2O5 and HfC, which stabilizes the volume changes induced by the formation of Ta2O5 and diminishes the generation of gaseous products. Also, the formation of solid solutions disturbs the atomic arrangement inside the lattice, which delays the reaction between Ta and O. Both of these mechanisms lead to the improved oxidation resistances of TaC-HfC solid solutions.

  19. Flexible, Luminescent Metal-Organic Frameworks Showing Synergistic Solid-Solution Effects on Porosity and Sensitivity.

    Science.gov (United States)

    Liu, Si-Yang; Zhou, Dong-Dong; He, Chun-Ting; Liao, Pei-Qin; Cheng, Xiao-Ning; Xu, Yan-Tong; Ye, Jia-Wen; Zhang, Jie-Peng; Chen, Xiao-Ming

    2016-12-23

    Mixing molecular building blocks in the solid solution manner is a valuable strategy to obtain structures and properties in between the isostructural parent metal-organic frameworks (MOFs). We report nonlinear/synergistic solid-solution effects using highly related yet non-isostructural, phosphorescent CuI triazolate frameworks as parent phases. Near the phase boundaries associated with conformational diversity and ligand heterogeneity, the porosity (+150 %) and optical O2 sensitivity (410 times, limit of detection 0.07 ppm) can be drastically improved from the best-performing parent MOFs and even exceeds the records hold by precious-metal complexes (3 ppm) and C70 (0.2 ppm). © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Luminescence properties of solid solutions LuxY1-xPO4:Eu3+

    Science.gov (United States)

    Levushkina, V. S.; Spassky, D. A.; Tretyakova, M. S.; Zadneprovski, B. I.; Kamenskikh, I. A.; Vasil'ev, A. N.; Belsky, A.

    2018-01-01

    Solid solutions LuxY1-xPO4 doped with Eu3+ were synthesized by the sol-gel method. Luminescence spectra under UV and X-ray excitation and luminescence excitation spectra in the UV-VUV energy range are presented. Observed variations of the structure of 4f-4f Eu3+ lines with the composition of the solid solution are explained by the fluctuations in the distribution of substitutional cations. The role of electronic structure modification in the fundamental absorption region with changing Y/Lu ratio is discussed and is suggested as the origin of different efficiency of energy transfer to Eu3+ in this region. Temperature dependence of the luminescence yield is related to the competition between emission centers and traps.

  1. Experimental and theoretical investigation of Cr1-xScxN solid solutions for thermoelectrics

    DEFF Research Database (Denmark)

    Kerdsongpanya, Sit; Sun, Bo; Eriksson, Fredrik

    2016-01-01

    The ScN- and CrN-based transition-metal nitrides have recently emerged as a novel and unexpected class of materials for thermoelectrics. These materials constitute well-defined model systems for investigating mixing thermodynamics, phase stability, and band structure aiming for property tailoring....... Here, we demonstrate an approach to tailor their thermoelectric properties by solid solutions. The trends in mixing thermodynamics and densities-of-states (DOS) of rocksalt-Cr1-xScxN solid solutions (0 ≤ x ≤ 1) are investigated by first-principles calculations, and Cr1-xScxN thin films are synthesized...... factors above that expected from the rule-of-mixture. These results corroborate the theoretical predictions and enable tailoring and understanding of structure-transport-property correlations of Cr1-xScxN....

  2. The elastic solid solution model for minerals at high pressures and temperatures

    Science.gov (United States)

    Myhill, R.

    2018-02-01

    Non-ideality in mineral solid solutions affects their elastic and thermodynamic properties, their thermobaric stability, and the equilibrium phase relations in multiphase assemblages. At a given composition and state of order, non-ideality in minerals is typically modelled via excesses in Gibbs free energy which are either constant or linear with respect to pressure and temperature. This approach has been extremely successful when modelling near-ideal solutions. However, when the lattice parameters of the solution endmembers differ significantly, extrapolations of thermodynamic properties to high pressures using these models may result in significant errors. In this paper, I investigate the effect of parameterising solution models in terms of the Helmholtz free energy, treating volume (or lattice parameters) rather than pressure as an independent variable. This approach has been previously applied to models of order-disorder, but the implications for the thermodynamics and elasticity of solid solutions have not been fully explored. Solid solution models based on the Helmholtz free energy are intuitive at a microscopic level, as they automatically include the energetic contribution from elastic deformation of the endmember lattices. A chemical contribution must also be included in such models, which arises from atomic exchange within the solution. Derivations are provided for the thermodynamic properties of n-endmember solutions. Examples of the use of the elastic model are presented for the alkali halides, pyroxene, garnet, and bridgmanite solid solutions. Elastic theory provides insights into the microscopic origins of non-ideality in a range of solutions, and can make accurate predictions of excess enthalpies, entropies, and volumes as a function of volume and temperature. In solutions where experimental data are sparse or contradictory, the Helmholtz free energy approach can be used to assess the magnitude of excess properties and their variation as a function

  3. Structural modifications of polymethacrylates: impact on thermal behavior and release characteristics of glassy solid solutions.

    Science.gov (United States)

    Claeys, Bart; De Coen, Ruben; De Geest, Bruno G; de la Rosa, Victor R; Hoogenboom, Richard; Carleer, Robert; Adriaensens, Peter; Remon, Jean Paul; Vervaet, Chris

    2013-11-01

    Polymethacrylates such as Eudragit® polymers are well established as drug delivery matrix. Here, we synthesize several Eudragit E PO (n-butyl-, dimethylaminoethyl-, methyl-methacrylate-terpolymer) analogues via free radical polymerization. These polymers are processed via hot melt extrusion, followed by injection molding and evaluated as carriers to produce immediate release solid solution tablets. Three chemical modifications increased the glass transition temperature of the polymer: (a) substitution of n-butyl by t-butyl groups, (b) reduction of the dimethylaminoethyl methacrylate (DMAEMA) content, and (c) incorporation of a bulky isobornyl repeating unit. These structural modifications revealed the possibility to increase the mechanical stability of the tablets via altering the polymer Tg without influencing the drug release characteristics and glassy solid solution forming properties. The presence of DMAEMA units proved to be crucial with respect to API/polymer interaction (essential in creating glassy solid solutions) and drug release characteristics. Moreover, these chemical modifications accentuate the need for a more rational design of (methacrylate) polymer matrix excipients for drug formulation via hot melt extrusion and injection molding. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Characterization of powellite-based solid solutions by site-selective time resolved laser fluorescence spectroscopy.

    Science.gov (United States)

    Schmidt, Moritz; Heck, Stephanie; Bosbach, Dirk; Ganschow, Steffen; Walther, Clemens; Stumpf, Thorsten

    2013-06-21

    We present a comprehensive study of the solid solution system Ca2(MoO4)2-NaGd(MoO4)2 on the molecular scale, by means of site-selective time resolved laser fluorescence spectroscopy (TRLFS). Eu(3+) is used as a trace fluorescent probe, homogeneously substituting for Gd(3+) in the solid solution crystal structure. Site-selective TRLFS of a series of polycrystalline samples covering the whole composition range of the solid solution series from 10% substitution of Ca(2+) to the NaGd end-member reveals it to be homogeneous throughout the whole range. The trivalent ions are incorporated into the powellite structure in only one coordination environment, which exhibits a very strong ligand-metal interaction. Polarization-dependent measurements of a single crystal of NaGd(Eu)(MoO4)2 identify the coordination geometry to be of C2v point symmetry. The S4 symmetry of the Ca site within the powellite lattice can be transformed into C2v assuming minor motion in the first coordination sphere.

  5. Berkovich nanoindentation and deformation mechanisms in a hardmetal binder-like cobalt alloy

    OpenAIRE

    Roa Rovira, Joan Josep; Jiménez Piqué, Emilio; Tarragó Cifre, Jose María; Zivcec, Maria; Broeckmann, C.; Llanes Pitarch, Luis Miguel

    2014-01-01

    A cobalt-base solid solution is the most used binder for hardmetals (WC–Co cemented carbides) in a wide range of industrial applications. In the composite material such cobalt alloy is surrounded by hard carbides grains; thus, a direct evaluation of its intrinsic mechanical properties is not an easy task. In order to overcome this inconvenience, a model cobalt alloy with a composition similar to that exhibited by typical hardmetal binder (containing W and C in solid solution) was processed fo...

  6. Temperature induced phase transformations and microstructural changes in nanostructured FeCu solid solutions using in situ neutron powder thermo-diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Blanco, D. [Unidad de Magnetometria, SCT' s, Universidad de Oviedo, Julian Claveria, 8, 33006 Oviedo (Spain); Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo s/n, Oviedo 33007 (Spain); Gorria, P., E-mail: pgorria@uniovi.e [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo s/n, Oviedo 33007 (Spain); Blanco, J.A. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo s/n, Oviedo 33007 (Spain); Smith, R.I. [ISIS facility, RAL, Chilton, Didcot, Oxon OX11 0QX (United Kingdom)

    2009-08-26

    In situ neutron powder thermo-diffraction experiments in the temperature range from 300 K to 1170 K have been carried out in nanostructured and metastable Fe{sub 15}Cu{sub 85} and Fe{sub 85}Cu{sub 15} solid solutions, which were synthesized by means of a mechanical alloying technique. We report on the microstructural changes and the phase transformations that take place during controlled heating and cooling processes. The average crystalline grain size is similar for both samples in the as-milled state (approx16-20 nm) while the induced strain is 2.5 times higher in the Fe-rich powders, reaching 1%. Moreover, the alpha-gamma transformation for Fe{sub 15}Cu{sub 85} starts at temperatures lower (approx900 K) than that expected for pure Fe (1183 K) due likely to the existence of local inhomogeneities in the composition of the ball milled material.

  7. Preparation of solid-solution type Fe-Co nanoalloys by synchronous deposition of Fe and Co using dual arc plasma guns.

    Science.gov (United States)

    Sadakiyo, Masaaki; Heima, Minako; Yamamoto, Tomokazu; Matsumura, Syo; Matsuura, Masashi; Sugimoto, Satoshi; Kato, Kenichi; Takata, Masaki; Yamauchi, Miho

    2015-09-28

    We succeeded in the efficient preparation of well-dispersed Fe-Co nanoalloys (NAs) using the arc plasma deposition method. Synchronous shots of dual arc plasma guns were applied to a carbon support to prepare the solid-solution type Fe-Co NAs having an approximately 1 : 1 atomic ratio. The alloy structures with and without a reductive thermal treatment under a hydrogen atmosphere were examined using X-ray powder diffraction, scanning transmission electron microscopy (STEM) combined with energy-dispersive X-ray analysis, high resolution STEM, and magnetic measurements, suggesting that highly crystalline spherical particles of ordered B2-type Fe-Co NAs form by the thermal treatment of the deposited grains.

  8. Scanning proximal microscopy study of the thin layers of silicon carbide-aluminum nitride solid solution manufactured by fast sublimation epitaxy

    Directory of Open Access Journals (Sweden)

    Tománek P.

    2013-05-01

    Full Text Available The objective of the study is a growth of SiC/(SiC1−x(AlNx structures by fast sublimation epitaxy of the polycrystalline source of (SiC1−x(AlNx and their characterisation by proximal scanning electron microscopy and atomic force microscopy. For that purpose optimal conditions of sublimation process have been defined. Manufactured structures could be used as substrates for wide-band-gap semiconductor devices on the basis of nitrides, including gallium nitride, aluminum nitride and their alloys, as well as for the production of transistors with high mobility of electrons and also for creation of blue and ultraviolet light emitters (light-emitted diodes and laser diodes. The result of analysis shows that increasing of the growth temperature up to 2300 K allows carry out sublimation epitaxy of thin layers of aluminum nitride and its solid solution.

  9. Structure of nanocomposites of Al–Fe alloys prepared by ...

    Indian Academy of Sciences (India)

    Wintec

    Abstract. Structures of Al-based nanocomposites of Al–Fe alloys prepared by mechanical alloying (MA) and subsequent annealing are compared with those obtained by rapid solidification processing (RSP). MA pro- duced only supersaturated solid solution of Fe in Al up to 10 at.% Fe, while for higher Fe content up to 20 at.

  10. Autocatalytic continuous precipitation in an Al-8 wt. % Mg alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hamana, D.; Nebti, S.; Boutefnouchet, A.; Chekroud, S. (Research Unit of Materials Physics, Constantine Univ. (Algeria))

    1993-01-01

    The precipitation mechanism of a supersaturated solid solution of Al-8 wt.% Mg alloy is studied. An autocatalytic continuous reaction due to a heterogeneous nucleation and growth into grains, is observed in this alloy where usually only continuous precipitation can occur. It has been shown that preceding cold working and dynamic deformation, using ultrasonic vibration, have no influence on this heterogeneous precipitation. (orig.).

  11. Local atomic structure of solid solutions with overlapping shells by EXAFS: The regularization method

    Energy Technology Data Exchange (ETDEWEB)

    Babanov, Yu.A., E-mail: babanov@imp.uran.ru [M.N. Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, Ekaterinburg 620990 (Russian Federation); Ponomarev, D.A.; Ustinov, V.V. [M.N. Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, Ekaterinburg 620990 (Russian Federation); Baranov, A.N. [M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Zubavichus, Ya.V. [Russian Research Centre “Kurchatov Institute”, 123182 Moscow (Russian Federation)

    2016-08-15

    Highlights: • A method for determining bond lengths from combined EXAFS spectra for solid oxide solutions is proposed. • We have demonstrated a high resolution in r-space of close spacing atoms in the Periodical Table. • These results were obtained without any assumptions concerning interatomic distances for multi-component systems. • Coordinates ions for the solid solution with rock salt structure are determined. - Abstract: The regularization method of solving ill-posed problem is used to determine five partial interatomic distances on the basis of combined two EXAFS spectra. Mathematical algorithm and experimental results of the EXAFS analysis for Ni{sub c}Zn{sub 1−c}O (c = 0.0, 0.3, 0.5, 0.7, 1.0) solid solutions with the rock salt (rs) crystal structure are discussed. Samples were synthesized from the binary oxide powders at pressure of 7.7 GPa and temperatures 1450–1650 K. The measurements were performed using synchrotron facilities (Russian Research Centre “Kurchatov Institute”, Moscow). The Ni and Zn K absorption spectra were recorded in transmission mode under room temperature. It is shown, the ideal rock salt lattice is distorted and long-range order exists only in the average (Vegard law). In order to determine coordinates ions for the solid solution with rock salt structure, we used the Pauling model. The simulation is performed for 343,000 cluster of oxide ions. The distribution functions for ions (Ni−O, Ni−Ni, Ni−Zn, Zn−Zn, Zn−O, O−O) depending on the distance are obtained. The width of the Gaussian distribution function is determined by the difference of the radii of the metal ions. The results are consistent with the data both X-ray diffraction and the EXAFS spectroscopy.

  12. Superficial composition in binary solid solutions A(B): Drastic effect of pure element surface tensions

    Science.gov (United States)

    Rolland, A.; Aufray, B.

    1985-10-01

    This paper deals with a comparative study of surface segragation of Pb and Ni respectively from Ag(Pb)(111) and Ag(Ni)(111) solid solutions. A high level of segregation of the solute is observed for both systems characterized by very low solute solubility. However, the superficial composition strongly depends on the relative surface tensions of the pure elements: the solute atoms are strictly on superficial sites when γ solute is smaller than γ solvent; in contrast uppermost layer consists purely of solvent when γ solute is greater than γ solvent. Two schematic distributions in close proximity to the surface are proposed in the last case.

  13. A New Class of Ternary Compound for Lithium-Ion Battery: from Composite to Solid Solution.

    Science.gov (United States)

    Wang, Jiali; Wu, Hailong; Cui, Yanhua; Liu, Shengzhou; Tian, Xiaoqing; Cui, Yixiu; Liu, Xiaojiang; Yang, Yin

    2018-02-14

    Searching for high-performance cathode materials is a crucial task to develop advanced lithium-ion batteries (LIBs) with high-energy densities for electrical vehicles (EVs). As a promising lithium-rich material, Li 2 MnO 3 delivers high capacity over 200 mAh g -1 but suffers from poor structural stability and electronic conductivity. Replacing Mn 4+ ions by relatively larger Sn 4+ ions is regarded as a possible strategy to improve structural stability and thus cycling performance of Li 2 MnO 3 material. However, large difference in ionic radii of Mn 4+ and Sn 4+ ions leads to phase separation of Li 2 MnO 3 and Li 2 SnO 3 during high-temperature synthesis. To prepare solid-solution phase of Li 2 MnO 3 -Li 2 SnO 3 , a buffer agent of Ru 4+ , whose ionic radius is in between that of Mn 4+ and Sn 4+ ions, is introduced to assist the formation of a single solid-solution phase. The results show that the Li 2 RuO 3 -Li 2 MnO 3 -Li 2 SnO 3 ternary system evolves from mixed composite phases into a single solid-solution phase with increasing Ru content. Meanwhile, discharge capacity of this ternary system shows significantly increase at the transformation point which is ascribed to the improvement of Li + /e - transportation kinetics and anionic redox chemistry for solid-solution phase. The role of Mn/Sn molar ratio of Li 2 RuO 3 -Li 2 MnO 3 -Li 2 SnO 3 ternary system has also been studied. It is revealed that higher Sn content benefits cycling stability of the system because Sn 4+ ions with larger sizes could partially block the migration of Mn 4+ and Ru 4+ from transition metal layer to Li layer, thus suppressing structural transformation of the system from layered-to-spinel phase. These findings may enable a new route for exploring ternary or even quaternary lithium-rich cathode materials for LIBs.

  14. Methods of deoxygenating metals having oxygen dissolved therein in a solid solution

    Science.gov (United States)

    Zhang, Ying; Fang, Zhigang Zak; Sun, Pei; Xia, Yang; Zhou, Chengshang

    2017-06-06

    A method of deoxygenating metal can include forming a mixture of: a metal having oxygen dissolved therein in a solid solution, at least one of metallic magnesium and magnesium hydride, and a magnesium-containing salt. The mixture can be heated at a deoxygenation temperature for a period of time under a hydrogen-containing atmosphere to form a deoxygenated metal. The deoxygenated metal can then be cooled. The deoxygenated metal can optionally be subjected to leaching to remove by-products, followed by washing and drying to produce a final deoxygenated metal.

  15. Investigations on the optimization of phase and alloy compositions of Al-Cu-Si-Mg alloys

    Energy Technology Data Exchange (ETDEWEB)

    Eskin, D.G. (A.A. Baikov Inst. of Metallurgy, Russian Academy of Sciences, Moscow (Russia))

    1992-10-01

    The effect of the supersaturated solid solution composition on the phase composition of aging products in Al - (4 mass%) Cu-Si-Mg alloys has been investigated in a broad compositional range. The diagram of distribution of phase regions has been constructed for the Al-Cu (4 mass%)-Si-Mg alloys after aging at 170degC for 20 h. With cast and deformed alloys, it has been shown exemplarily that the best complex of mechanical properties is associated with alloy compositions ensuring the precipitation of [Theta]' and [beta]'' phases. The composition of cast Al - Si - Cu - Mg alloys has been optimized. (orig.).

  16. Incidental Abnormalities in Oral Mucosal Carcinogenesis of v-H-ras Transgenic Mice OF v-H-ras TRANSGENIC MICE

    Directory of Open Access Journals (Sweden)

    Dewi Agustina

    2012-10-01

    Full Text Available The effect of individual oncogene on diverse cell types could be studied by using transgenic mice. The expression of transgene is mainly determined by the regulatory sequences chosen. Fifty four v-H-ras transgenic FVB/N mice and 54 parental FVB/N mice were used as the experimental and the control groups respectively. Each group was divided into nine subgroups with three different treatments i.e. 4-nitroquinoline 1-oxide (4NQO-treated, phorbol 12,13-didecanoate (PDD-treated and propane-1,2-diol (PD-treated palatal of mice for 6, 16 or 24 weeks. Other four mice of parental mice were used as the untreated group. Two weeks after the last painting, all animals were sacrificed and the intra- or extra-oral tissues were removed and fixed in 4% m/v paraformaldehyde for 24 hours. Hard tissue were then decalcified after the fixation was completed. Subsequently, standard procedure for H&E staining was performed. The results of this study showed that 47 out of 54 transgenic mice produced spontaneous odontogenic, epidermal or mesenchymal neoplasms. After 24 weeks of painting with 4NQO there was minimal evidence of palatal epithelial dysplasia in both transgenic and parental strain groups and neither the PDD nor PD groups showed evidence of dysplasia. From these results it was apparent that the effect of 4NQO and PDD was slower than reported for other strain of mice and that activated v-H-ras did not increase the rate of palatal mucosal carcinogenesis in the model used. On the other hand, incidental abnormalities were much detected especially in the experimental group.DOI: 10.14693/jdi.v16i1.11

  17. Structure and Transport Properties of the BiCuSeO-BiCuSO Solid Solution

    Directory of Open Access Journals (Sweden)

    David Berardan

    2015-03-01

    Full Text Available In this paper, we report on the crystal structure and the electrical and thermal transport properties of the BiCuSe1−xSxO series. From the evolution of the structural parameters with the substitution rate, we can confidently conclude that a complete solid solution exists between the BiCuSeO and BiCuSO end members, without any miscibility gap. However, the decrease of the stability of the materials when increasing the sulfur fraction, with a simultaneous volatilization, makes it difficult to obtain S-rich samples in a single phase. The band gap of the materials linearly increases between 0.8 eV for BiCuSeO and 1.1 eV in BiCuSO, and the covalent character of the Cu-Ch (Ch = chalcogen element, namely S or Se here bond slightly decreases when increasing the sulfur fraction. The thermal conductivity of the end members is nearly the same, but a significant decrease is observed for the samples belonging to the solid solution, which can be explained by point defect scattering due to atomic mass and radii fluctuations between Se and S. When increasing the sulfur fraction, the electrical resistivity of the samples strongly increases, which could be linked to an evolution of the energy of formation of copper vacancies, which act as acceptor dopants in these materials.

  18. B-site substituted solid solutions on the base of sodium-bismuth titanate

    Directory of Open Access Journals (Sweden)

    V. M. Ishchuk

    2016-12-01

    Full Text Available The paper presents results of studies of the formation of phases during the solid-state synthesis in the [(Na0.5Bi0.50.80Ba0.20](Ti1–yByO3 system of solid solutions with B-site substitutions. The substitutions by zirconium, tin and ion complexes (In0.5Nb0.5 and (Fe0.5Nb0.5 have been studied. It has been found that the synthesis is a multi-step process associated with the formation of a number of intermediate phases (depending on the compositions and calcination temperatures. Single-phase solid solutions have been produced at the calcination temperatures in the interval 1000–1100∘C. An increase in the substituting ions concentration leads to a linear increase of the crystal cell size. At the same time, the tolerance factor gets reduced boosting the stability of the antiferroelectric phase as compared to that of the ferroelectric phase.

  19. Chemically deposited Bi2S3:PbS solid solution thin film as supercapacitive electrode.

    Science.gov (United States)

    Pandit, Bidhan; Sharma, Gagan Kumar; Sankapal, Babasaheb R

    2017-11-01

    Low-cost, easily synthesized, and high energy/power density embedded stable supercapacitive electrodes are the demands for today's renewable and green energy dependent generation. In search of that, Bi2S3:PbS solid solution in thin film form has been synthesized by modest successive ionic layer adsorption and reaction (SILAR) method and characterized by XRD, FESEM, and HRTEM. Formation of solid solution in the form of nanoparticles gilded thin film exposes sufficient electroactive cavities for electroactive ions to incorporate. The composite exhibited excellent specific capacitance of 402.4F/g at current density of 1mA/cm2 with modest charge-discharge cycles. In terms of energy storage, it exhibited maximum specific power of 20.1Wh/kg with accepting specific power of 1.2kW/kg. The combination of two nanoparticles in nanocomposites thin film supplies new tactic for energy storage applications. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Mössbauer spectroscopy investigation of lithium oxide-hematite solid solution

    Science.gov (United States)

    Bushunow, Vasilii; Sorescu, Monica

    2013-03-01

    Lithium oxide-doped hematite xLi2O * (1- x) α-Fe2O3 (x = 0.1-0.7) solid solutions were prepared via ball milling. Samples were taken at 0, 2, 4, 8, and 12 hours ball milling time (BMT). Parameters for the obtained Mössbauer spectra were determined by least-squares fitting using NORMOS-90 software. For all initial Li2O concentrations, partial substitution of Fe3+ in the Li2O lattice and vice versa was seen beginning at two hours BMT. For x = 0.1, 0.3, and 0.5, spectra were fit with one or two sextets and one quadrupole-split doublet. For x = 0.7, all spectra were fit with a single sextet and one quadrupole-split doublet. With increased BMT, the abundance of the doublet increased, irrespective of initial Li2O concentration. For example, the abundance of the doublet increased from 2.3% at 2 h BMT to 11.1% at 12 h BMT for x = 0.1. The increasing abundance of the doublet indicates greater substitution of Li+ by Fe3+ in the Li2O lattice. Increasing the initial concentration of Li2O for constant BMT did not consistently increase the abundance of the doublet. The results of this experiment demonstrate the feasibility of forming solid solutions by purely mechanical methods, e.g. ball milling.

  1. Structure and magnetic properties of metastable Co-Cu solid solution nanowire arrays fabricated by electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Tao; Li, Fashen; Wang, Ying; Song, Lijing [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou Univesity, Lanzhou 730000 (China)

    2006-08-15

    Nanowire arrays of the metastable Co{sub x}Cu{sub 1-x} (0.20{<=}x{<=}0.85) solid solution system which can not be obtained by equilibrium methods, were prepared by electrodeposition in pores of anodic aluminum oxide (AAO) template, and subsequently annealed at different temperatures. The as-deposited samples all show single phase of fcc structure, and lattice parameters decrease with the increase of Co content and fundamentally accord with Vegard's law. The phase transition with heat treatment was investigated by X-ray diffraction and differential thermal analysis (DTA) which further confirmed the formation of solid solution. With Co content increasing, the coercivity along nanowire axis for as-deposited samples increases, but it decreases for the annealed samples at 700 C. This phenomenon was explained considering the interaction of Co particles through Cu in nanowires after phase separation. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. The origin of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution crystals

    Energy Technology Data Exchange (ETDEWEB)

    Li, Fei; Zhang, Shujun; Yang, Tiannan; Xu, Zhuo; Zhang, Nan; Liu, Gang; Wang, Jianjun; Wang, Jianli; Cheng, Zhenxiang; Ye, Zuo-Guang; Luo, Jun; Shrout, Thomas R.; Chen, Long-Qing (Penn); (Xian Jiaotong); (CIW); (Simon); (TRS Techn); (Wollongong)

    2016-12-19

    The discovery of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution single crystals is a breakthrough in ferroelectric materials. A key signature of relaxor-ferroelectric solid solutions is the existence of polar nanoregions, a nanoscale inhomogeneity, that coexist with normal ferroelectric domains. Despite two decades of extensive studies, the contribution of polar nanoregions to the underlying piezoelectric properties of relaxor ferroelectrics has yet to be established. Here we quantitatively characterize the contribution of polar nanoregions to the dielectric/piezoelectric responses of relaxor-ferroelectric crystals using a combination of cryogenic experiments and phase-field simulations. The contribution of polar nanoregions to the room-temperature dielectric and piezoelectric properties is in the range of 50–80%. A mesoscale mechanism is proposed to reveal the origin of the high piezoelectricity in relaxor ferroelectrics, where the polar nanoregions aligned in a ferroelectric matrix can facilitate polarization rotation. This mechanism emphasizes the critical role of local structure on the macroscopic properties of ferroelectric materials.

  3. Multiferroic phase boundaries and properties of BiFeO3-based solid solutions

    Science.gov (United States)

    Ye, Zuo-Guang

    The presence of morphotropic phase boundary in ferroelectric solid solutions (FE-MPB) is known to be crucial for high piezoelectricity. Similarly, magnetic MPB (M-MPB) is found in a few ferromagnets and is proved to be greatly beneficial to the magnetostricitive response. One naturally asks if in multiferroics that exhibit both ferroelectricity and (ferro-/antiferro-)magnetism, the FE-MPB and M-MPB could exist simultaneously, and if so, what the relation between these two kinds of MPB would be, and how they would affect the properties. In this paper, we report the studies of ferroelectric and magnetic double morphotropic phase boundaries in BiFeO3-based multiferroics. The effects of dysprosium ion on the structure and local polar domains of the BiFeO3-based systems were investigated firstly in the Dy-substituted solid solutions of 0.66Bi1-x DyxFeO3-0.34PbTiO3. It is found that the substitution of Dy affects the structural symmetry and phase component of the multiferroic solid solution, and thereby enhances its ferroelectric order. A (weak) ferromagnetic state is induced at room temperature for the rhombohedral compositions with x >= 0.10. The introduction of Dy into 0.66BiFeO3-0.34PbTiO3 leads to the breaking of its antiferromagnetic order below Néel temperature and thereby the formation of (weak) ferromagnetic ordering at room temperature when the substitution rate exceeds a critical value (x >= 0.10), making the 0.66Bi1-x DyxFeO3-0.34PbTiO3 system one of rare room-temperature ferromagnetic and ferroelectric materials, i.e. a true multifrroic. A comprehensive ferroelectric-magnetic phase diagram is established in terms of temperature and composition, which depicts the coexistence of a FE-MPB and a FM-MPB. These two kinds of MPBs overlap with each other. Such unusual coincidence of both magnetic MPB and ferroelectric MPB, the so-called double MPB, points to new kinds of couplings among the multiple physical quantities so that such effects as magnetoelectricity

  4. Solid solution formation between vanadium(V) and tungsten(V) oxide phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Subrata Chandra; Glaum, Robert [Institut fuer Anorganische Chemie, Rheinische Friedrich-Wilhelms-Universitaet Bonn (Germany); Abdullin, Dinar; Schiemann, Olav [Institut fuer Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universitaet Bonn (Germany); Bac, Nguyen Quang; Lii, Kwang-Hwa [Department of Chemistry, National Central University, Jhongli, Taiwan (China)

    2014-08-15

    The solid solutions (V{sub 1-x}W{sub x})OPO{sub 4} with β-VOPO{sub 4} structure type (0.0 ≤ x ≤ 0.01) and α{sub II}-VOPO{sub 4} structure type (0.04 ≤ x ≤ 0.26) were obtained from mixtures of V{sup V}OPO{sub 4} and W{sup V}OPO{sub 4} by conventional solid state reactions and by solution combustion synthesis. Single crystals of up to 3 mm edge length were obtained by chemical vapor transport (CVT) (800 → 700 C, Cl{sub 2} as a transporting agent). Single crystal structure refinements of crystals at x = 0.10 [a = 6.0503(2) Aa, c = 4.3618(4) Aa, R{sub 1} = 0.021, wR{sub 2} = 0.058, 21 parameters, 344 independent reflections] and x = 0.26 [a = 6.0979(2) Aa, c = 4.2995(1) Aa, R{sub 1} = 0.030, wR{sub 2} = 0.081, 21 parameters, 346 independent reflections] confirm the α{sub II}-VOPO{sub 4} structure type (P4/n, Z = 2) with mixed occupancy V/W for the metal site. Due to the specific redox behavior of W{sup 5+} and V{sup 5+}, solid solutions (V{sub 1-x}W{sub x})OPO{sub 4} should be formulated as (V{sup IV}{sub x}V{sup V}{sub 1-2x}W{sup VI}{sub x})OPO{sub 4}. The valence states of vanadium and tungsten are confirmed by XPS measurements. V{sup 4+} with d{sup 1} configuration was identified by EPR spectroscopy and magnetic measurements. Electronic spectra of the solid solutions show the IVCT(V{sup 4+} → V{sup 5+}) and the LMCT(O{sup 2-} → V{sup 5+}). (V{sub 0.74}W{sub 0.26})OPO{sub 4} powders exhibit semi-conducting behavior (E{sub g} = 0.7 eV). (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Crystalline structure and electrical properties of Dy1-XCaXMnO3 solid solution

    Directory of Open Access Journals (Sweden)

    Durán, P.

    2002-12-01

    Full Text Available Solid solutions corresponding to the Dy1-xCaXMnO3 system, x=0.0 to 0.60 have been studied. The powders were prepared by solid state reaction of the corresponding oxides and carbonates. Sintered bodies were obtained by firing between 1250 and 1450ºC. All the compositions showed single-phased perovskite-type structure with orthorhombic symmetry and Space Group Pbnm. Increase of the CaO content leads to a monotonic decrease of the orthorhombicity factor b/a with the Ca2+ concentration up to x=0.60. All the solid solutions crystallised with the same O’-type orthorhombic perovskite structure such as pure DyMnO3. Electrical measurements have shown semiconducting behaviour for all the solid solutions. The room temperature conductivity increases monotonically with the CaO content. The 60/40 Ca/Dy composition showed a high value of the electrical conductivity and a correlative very low value of the activation energy. Thermally activated small polaron hopping mechanism controls the conductivity of these perovskite ceramics.Se han estudiado soluciones sólidas correspondientes al sistema Dy1-xCaxMnO3, x=0.0 a 0.60. Los polvos cerámicos fueron preparados por reacción en estado sólido de los correspondientes óxidos y carbonatos. Los materiales cerámicos se obtuvieron por sinterización entre 1250º y 1450ºC. Todas las composiciones fueron monofásicas y mostraron una estructura tipo perovskita, con simetría ortorrómbica y Grupo Espacial Pbnm. El aumento del contenido en CaO llevó a una disminución monótona del factor de ortorrombicidad, b/a. Todas las soluciones sólidas cristalizaron con el mismo tipo de estructura perovskita ortorrómbica O’, como la del compuesto puro DyMnO3. Las medidas eléctricas mostraron comportamiento semiconductor en todas las soluciones sólidas. La conductividad a temperatura ambiente aumenta monótonamente con el contenido de CaO. La composición 60/40 mostró un elevado valor de conductividad y un correlativo

  6. Synthesis of GaN:ZnO solid solution by solution combustion method and characterization for photocatalytic application

    Science.gov (United States)

    Menon, Sumithra Sivadas; Anitha, R.; Gupta, Bhavana; Baskar, K.; Singh, Shubra

    2016-05-01

    GaN-ZnO solid solution has emerged as a successful and reproducible photocatalyst for overall water splitting by one-step photoexcitation, with a bandgap in visible region. When the solid solution is formed, some of the Zn and O ions are replaced by Ga and N ions respectively and there is a narrowing of bandgap which is hypothesized as due to Zn3d-N2p repulsion. The traditional method of synthesis of GaN-ZnO solid solution is by nitridation of the starting oxides under constant ammonia flow. Here we report a solution combustion technique for the synthesis of the solid solution at a temperature about 500 ° C in a muffle furnace with metal nitrates as precursors and urea as the fuel. The as prepared samples showed change in color with the increased concentration of ZnO in the solution. The structural, microstructural, morphological and optical properties of the samples were realized by Powder X ray diffraction, Scanning electron microscopy, Energy dispersive X ray analysis, Transmission electron microscopy and Photoluminescence. Finally the hydrogen production efficiency of the GaN-ZnO nanopowders by water splitting was found, using methanol as a scavenger. The apparent quantum yield (AQY) of 0.048% is obtained for GaN-ZnO solid solution.

  7. Synthesis of GaN:ZnO solid solution by solution combustion method and characterization for photocatalytic application

    Energy Technology Data Exchange (ETDEWEB)

    Menon, Sumithra Sivadas; Anitha, R.; Baskar, K.; Singh, Shubra, E-mail: shubra6@gmail.com [Crystal Growth Centre, Anna University, Chennai-600025 (India); Gupta, Bhavana [Material Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

    2016-05-23

    GaN-ZnO solid solution has emerged as a successful and reproducible photocatalyst for overall water splitting by one-step photoexcitation, with a bandgap in visible region. When the solid solution is formed, some of the Zn and O ions are replaced by Ga and N ions respectively and there is a narrowing of bandgap which is hypothesized as due to Zn3d-N2p repulsion. The traditional method of synthesis of GaN-ZnO solid solution is by nitridation of the starting oxides under constant ammonia flow. Here we report a solution combustion technique for the synthesis of the solid solution at a temperature about 500 ° C in a muffle furnace with metal nitrates as precursors and urea as the fuel. The as prepared samples showed change in color with the increased concentration of ZnO in the solution. The structural, microstructural, morphological and optical properties of the samples were realized by Powder X ray diffraction, Scanning electron microscopy, Energy dispersive X ray analysis, Transmission electron microscopy and Photoluminescence. Finally the hydrogen production efficiency of the GaN-ZnO nanopowders by water splitting was found, using methanol as a scavenger. The apparent quantum yield (AQY) of 0.048% is obtained for GaN-ZnO solid solution.

  8. Synthesis, characterization and thermal stability of solid solutions Zr (Y, Fe, MoO2

    Directory of Open Access Journals (Sweden)

    Felipe Legorreta-García

    2015-05-01

    Full Text Available The synthesis of Fe3+, Mo4+ and Y3+ fully stabilized zirconia by the nitrate/urea combustion route and thermal stability in air was investigated. The solid solution obtained was characterized by X ray diffraction (XRD, scanning electron microscopy (SEM and used the BET method for determining specific surface. The ceramic powders obtained were calcined at 1473 K in air atmosphere in order to determine their thermal stability. The scanning electron microscopy (SEM results showed a homogeneous grain surface, measuring several tens of micrometers across. The crystallographic study revealed that by this method it was successfully achieved zirconia doped with Fe3+, Mo4+ and Y3+ ions in the zirconia tetragonal monophase, even after calcinations.

  9. Growth and electronic properties of GaN/ZnO solid solution nanowires

    Science.gov (United States)

    Han, Wei-Qiang; Zhang, Yan; Nam, Chang-Yong; Black, C. T.; Mendez, E. E.

    2010-08-01

    We have grown single-crystal (Ga1-xZnx)(N1-xOx) solid-solution nanowires using nanostructured ZnGa2O4 precursor prepared by a sol-gel method. From electrical transport measurements in individual nanowire field-effect transistors, we have identified the conduction as n-type and obtained a background carrier density (˜1019 cm-3) and an electron mobility (˜1 cm2/V s) that are consistent with chemical disorder and a large number of charge traps, as confirmed by the devices' photocurrent response. From the dependence of the device photoresponse on incident light wavelength, we have determined the energy band gap of (Ga0.88Zn0.12)(N0.88O0.12) to be as much as ˜0.6 eV lower than that of GaN or ZnO.

  10. Free Volumes Associated with Sintering in Gadolinium Doped Ceria Solid Solutions

    Directory of Open Access Journals (Sweden)

    Tomomi Kosaka

    2010-01-01

    Full Text Available Gadolinium-doped ceria (GDC solid solution prepared by the oxalate coprecipitation method is investigated by X-ray diffraction (XRD, complex impedance analysis, and positron lifetime spectroscopy. XRD reveals an expansion of GDC lattice constant by doping gadolinium into a ceria host crystal, in agreement with an oxygen vacancy model. The ionic conductivity of GDC measured at 773 K in air is two orders of magnitude higher than that of undoped ceria. Positron lifetime spectroscopy reveals the presence of vacancy-sized free volumes and nanovoids in interfaces among crystallites. It is found that the vacancy-sized free volumes shrink with increasing sintering temperatures. In the present paper, recent advances in the studies of GDC by XRD, complex impedance measurement, and positron lifetime spectroscopy are reviewed to gain an insight into the sintering mechanism.

  11. Synthesis, characterization and thermal stability of solid solutions Zr (Y, Fe, Mo)O {sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Legorreta-Garcia, F.; Esperanza Hernandez-Cruz, L.; Villanueva-Ibanez, M.; Flores-Gonzalez, M. A.

    2015-10-01

    The synthesis of Fe{sup 3}+, Mo{sup 4+} and Y{sup 3+} fully stabilized zirconia by the nitrate/urea combustion route and thermal stability in air was investigated. The solid solution obtained was characterized by X ray diffraction (XRD), scanning electron microscopy (SEM) and used the BET method for determining specific surface. The ceramic powders obtained were calcined at 1473 K in air atmosphere in order to determine their thermal stability. The scanning electron microscopy (SEM) results showed a homogeneous grain surface, measuring several tens of micrometers across. The crystallographic study revealed that by this method it was successfully achieved zirconia doped with Fe{sup 3+}, Mo{sup 4+} and Y{sup 3+} ions in the zirconia tetragonal monophase, even after calcinations. (Author)

  12. Generation of WO 3-ZrO 2 catalysts from solid solutions of tungsten in zirconia

    Science.gov (United States)

    Cortés-Jácome, María A.; Angeles-Chavez, Carlos; Bokhimi, Xim; Toledo-Antonio, J. A.

    2006-08-01

    WO 3-ZrO 2 samples were obtained by precipitating zirconium oxynitrate in presence of WO 4dbnd species in solution from ammonium metatungstate at pH=10.0. Samples were characterized by atomic absorption spectroscopy, thermal analysis, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy and energy filtered-TEM. The ammonia retained in the dried sample produced a reductive atmosphere to generate W 5+ ions coexisting with W 6+ ions to produce a solid solution of tungsten in the zirconia lattice to stabilize the zirconia tetragonal phase when the sample was annealed at 560 °C. When the sample was annealed at 800 °C, the W atoms near crystallite surface were oxidized to W 6+, producing patches of WO 3 on the zirconia crystallite. The HR-TEM analysis confirmed the existence of the solid solution when the sample was annealed at 560 °C, and two types of crystalline regions were identified: One with nearly spherical morphology, an average diameter of 8 nm and the atomic distribution of tetragonal zirconia. The second one had a non-spherical morphology with well-faceted faces and dimensions larger than 30 nm, and the atom distribution of tetragonal zirconia. When samples were annealed at 800 °C two different zirconia crystallites were formed: Those where only part of the dissolved tungsten atoms segregated to crystallite surface producing patches of nanocrystalline WO 3 on the crystallite surface of tetragonal zirconia stabilized with tungsten. The second type corresponded to monoclinic zirconia crystallites with patches of nanocrystalline WO 3 on their surface. The tungsten segregation gave rise to the WO 3-ZrO 2 catalysts.

  13. Investigating conceptual models for physical property couplings in solid solution models of cement

    Energy Technology Data Exchange (ETDEWEB)

    Benbow, Steven; Watson, Claire; Savage, David [Quintesssa Ltd., Henley-on-Thames (United Kingdom)

    2005-11-15

    The long-term behaviour of cementitious engineered barriers is an important process to consider when modelling the migration of radionuclides from a geological repository for nuclear waste. The modelling of cement is complicated by the fact that the cement is dominated by the behaviour of calcium silicate hydrate (CSH) gel which is a complex solid exhibiting incongruent dissolution behaviour. In this report, we have demonstrated the implementation of a solid-solution CSH gel model within a geochemical transport modelling framework using the Raiden computer code to investigate cement/concrete-groundwater interactions. The modelling conducted here shows that it is possible to couple various conceptual models for the evolution of physical properties of concrete with a solid solution model for cement degradation in a fully coupled geochemical transport model to describe the interaction of cement/concrete engineered barriers with groundwater. The results show that changes to the conceptual models and flow rates can give rise to very different evolutions. Most simulations were carried out at a reduced 'experimental' scale rather than full repository scale. The work has shown the possibility to investigate also the changing physical properties of degrading cement. To further develop the model more emphasis is needed on kinetics and the detailed development of a nearly clogged pore space. Modelling of the full repository scale could be another way forward to understand the behaviour of degrading concrete. A general conclusion is that the combined effects of chemical evolution and physical degradation should be analysed in performance assessments of cementitious repositories. Moreover, the project results will be used as one basis in coming reviews of SKB's safety assessments of repositories for spent fuel and low-and intermediate level waste.

  14. Analysis of thermoelectric properties of high-temperature complex alloys of nickel-base, iron-base and cobalt-base groups

    Science.gov (United States)

    Holanda, R.

    1984-01-01

    The thermoelectric properties alloys of the nickel-base, iron-base, and cobalt-base groups containing from 1% to 25% 106 chromium were compared and correlated with the following material characteristics: atomic percent of the principle alloy constituent; ratio of concentration of two constituents; alloy physical property (electrical resistivity); alloy phase structure (percent precipitate or percent hardener content); alloy electronic structure (electron concentration). For solid-solution-type alloys the most consistent correlation was obtained with electron concentration, for precipitation-hardenable alloys of the nickel-base superalloy group, the thermoelectric potential correlated with hardener content in the alloy structure. For solid-solution-type alloys, no problems were found with thermoelectric stability to 1000; for precipitation-hardenable alloys, thermoelectric stability was dependent on phase stability. The effects of the compositional range of alloy constituents on temperature measurement uncertainty are discussed.

  15. Photocatalytic hydrogen production over solid solutions between BiFeO{sub 3} and SrTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Lingwei; Lv, Meilin [Shanghai Key Lab of Chemical Assessment and Sustainability, Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai, 200092 (China); Liu, Gang [Shenyang National laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Science, 72 Wenhua Road, Shenyang 110016 (China); Xu, Xiaoxiang, E-mail: xxxu@tongji.edu.cn [Shanghai Key Lab of Chemical Assessment and Sustainability, Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai, 200092 (China)

    2017-01-01

    Graphical abstract: We have successfully prepared a series of SrTiO{sub 3}-BiFeO{sub 3} solid solutions. These materials own strong visible light absorption and demonstrate appealing photocatalytic activity under both full range and visible light irradiation. - Highlights: • Band gap values can be tuned by adjusting molar ratios between SrTiO{sub 3} and BiFeO{sub 3}. • Photocatalytic activity is greatly improved after constituting solid solutions. • Photocatalytic activity is influenced by surface area and light absorption. • Fe plays an important role for band gap reduction and catalytic activity. - Abstract: Constituting solid solutions has been an appealing means to gain control over various physicochemical properties. In this work, we synthesized a series of SrTiO{sub 3}-BiFeO{sub 3} solid solutions and systematically explored their structural, optical and photocatalytic properties. Our results show that all solid solutions crystallize in a primitive cubic structure and their band gap values can be easily tuned by adjusting molar ratios between SrTiO{sub 3} and BiFeO{sub 3}. Photocatalytic hydrogen production under both full range and visible light irradiation is greatly improved after forming solid solutions. The highest hydrogen production rate obtained is ∼180 μmol/h under full range irradiation (λ ≥ 250 nm) and ∼4.2 μmol/h under visible light irradiation (λ ≥ 400 nm), corresponding to apparent quantum efficiency ∼2.28% and ∼0.10%, respectively. The activity is found to be strongly influenced by surface area and light absorption. Theoretical calculation suggests that Fe contributes to the formation of spin-polarized bands in the middle of original band gap and is responsible for the band gap reduction and visible light photocatalytic activity.

  16. The recasting effects on the high gold dental alloy properties

    Directory of Open Access Journals (Sweden)

    Maksimović V.M.

    2015-01-01

    Full Text Available Noble dental alloys are often reused in dental practice by recasting. The aim of this study was to determine if repeated casting of high gold dental alloys has a detrimental effect on alloy microstructure, type of porosity, structure and microhardness. Results showed that recasting procedure had a strong effect on the change of alloy porosity type. It was also found that alloy microhardness increased with the increase of the number of recasting cycles. At the same time the grain growth and changes of the solid solution phases in the microstructure were observed. [Projekat Ministarstva nauke Republike Srbije, br. III 45012

  17. Mechanical properties and the electronic structure of transition metal alloys. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Arsenault, R.J.; Drew, H.D.

    1977-01-01

    This interdiscipline research program was undertaken in an effort to investigate the relationship between the mechanical strength of Mo-based alloys with their electronic structure. Electronic properties of these alloys were examined through optical studies, and the classical solid solution strengthening mechanisms were considered, based on size and molecular differences to determine if these mechanisms could explain the hardness data.

  18. Mechanical properties and the electronic structure of transition of metal alloys

    Science.gov (United States)

    Arsenault, R. J.; Drew, H. D.

    1977-01-01

    This interdiscipline research program was undertaken in an effort to investigate the relationship between the mechanical strength of Mo based alloys with their electronic structure. Electronic properties of these alloys were examined through optical studies, and the classical solid solution strengthening mechanisms were considered, based on size and molecular differences to determine if these mechanisms could explain the hardness data.

  19. Iron site occupancies in magnetite-ulvospinel solid solution: A new approach using XMCD

    Energy Technology Data Exchange (ETDEWEB)

    Pearce, C. I.; Henderson, C. M. B.; Telling, N. D.; Pattrick, R. A.D.; Vaughan, D. J.; Charnock, J. M.; Arenholz, E.; Tuna, F.; Coker, V.S.; Laan, G. van der

    2009-06-22

    Ordering of Fe{sup 3+} and Fe{sup 2+} between octahedral (Oh) and tetrahedral (Td) sites in synthetic members of the magnetite (Fe{sub 3}O{sub 4}) - ulvoespinel (Fe{sub 2}TiO{sub 4}) solid-solution series was determined using Fe L{sub 2,3}-edge X-ray magnetic circular dichroism (XMCD) coupled with electron microprobe and chemical analysis, Ti L-edge spectroscopy, Fe K-edge EXAFS and XANES, Fe{sub 57} Moessbauer spectroscopy, and unit cell parameters. Microprobe analysis, cell edges and chemical FeO determinations showed that the bulk compositions of the samples were stoichiometric magnetite-ulvoespinel solid-solutions. Surface sensitive XMCD showed that the surfaces of these oxide minerals were more sensitive to redox conditions and some samples required re-equilibration with suitable solid-solid buffers. Detailed site-occupancy analysis of these samples gave XMCD-Fe{sup 2+}/Fe{sup 3+} ratios very close to stoichiometric values. L{sub 2,3}-edge spectroscopy showed that Ti{sup 4+} was restricted to Oh sites. XMCD results showed that significant Fe{sup 2+} only entered Td when the Ti content was > 0.40 apfu while Fe{sup 2+} in Oh increased from 1 a.p.f.u in magnetite to a maximum of {approx}1.4 apfu in USP45. As the Ti content increased from this point, the steady increase in Fe{sup 2+} in Td sites was clearly observable in the XMCD spectra, concurrent with a slow decrease in Fe{sup 2+} in Oh sites. Calculated magnetic moments showed a steady decrease from magnetite (4.06 {mu}{sub B}) to USP45 (1.5 {mu}{sub B}) and then a slower decrease towards the value for ulvoespinel (0 {mu}{sub B}). Two of the synthesized samples were also partially maghemitized by re-equilibrating with an oxidizing Ni-NiO buffer and XMCD showed that Fe{sup 2+} oxidation only occurred at Oh sites, with concomitant vacancy formation restricted to this site. This study shows the advantage of using XMCD as a direct measurement of Fe oxidation state in these complex magnetic spinels. These results

  20. Crystalline structure and electrical properties of solid solutions YNixMn1-xO3

    Directory of Open Access Journals (Sweden)

    Moure, C.

    1999-12-01

    Full Text Available Solid solutions belonging to the Mn-rich region of the YNiXMn1-XO3 system have been studied. The powders were prepared by solid state reaction between the corresponding oxides. Sintered ceramics were obtained by firing at 1325-1350ºC. The incorporation of 20 atomic % Ni2+ to the Yttrium manganite induces the formation of a perovskite phase, with orthorhombic symmetry. Increase of the Ni amount leads to an increase of the orthorhombicity factor b/a, up to an amount of 50 atomic % Ni2+. Above this Ni amount, a biphasic system has been observed, with the presence of unreacted Y2O3. DC electrical conductivity measurements have shown semiconducting behaviour for all the solid solutions with perovskite-type structure. The room temperature conductivity increases with Ni until ~33 atomic % Ni, and then decreases. The 50/50 Ni/Mn composition has different values of conductivity and activation energy against those corresponding to samples with lower values of that ionic ratio. Small polaron hopping mechanism controls the conductivity in these ceramics. Results are discussed as a function of the Mn3+/Mn4+ ratio for each composition.Se han estudiado las soluciones sólidas correspondientes a la región rica en Mn del sistema YNiXMn1-XO3, entre 0 y 50 atomic % Ni. Los compuestos fueron preparados por reacción en estado sólido de los óxidos correspondientes. Se sinterizaron materiales cerámicos a 1325-1350ºC. Con cantidades de 20 atomic % Ni se produce la formación de una fase con estructura de perovskita, y simetría ortorrómbica. La distorsión ortorrómbica crece con el contenido de Ni. Por encima de 50 atomic % Ni, aparece Y2O3 sin reaccionar. Las soluciones sólidas muestran semiconducción con valores de σ que aumentan con el contenido de Ni hasta ~33 atomic %, para luego decrecer, hasta x=0.5. La composición 50/50 Ni/Mn muestra un comportamiento eléctrico algo diferente. Se discuten los resultados en función de la razón Mn3+/Mn4+ para cada

  1. Optical properties of TixSi1 -xO2 solid solutions

    Science.gov (United States)

    Ondračka, Pavel; Holec, David; Nečas, David; KedroÅová, Eva; Elisabeth, Stéphane; Goullet, Antoine; Zajíčková, Lenka

    2017-05-01

    In this work, we use density functional theory to predict the optical properties of TixSi1 -xO2 solid solutions. The special quasirandom structure method and the simulated annealing procedure were applied to produce models of crystalline and amorphous TixSi1 -xO2 . These were fully structurally optimized by using the vasp package, while their electronic structure and optical properties were subsequently calculated by using the wien2k package employing the TB-mBJ potential. The calculated band gaps for a-TixSi1 -xO2 evaluated by using the Tauc-like fitting approach are 8.53 eV for SiO2, quickly decreasing to 4.0 eV at x =0.19 , 3.52 eV at x =0.34 , and 3.24 eV for TiO2. Experimental samples were prepared by means of plasma-enhanced chemical vapor deposition to support the calculations. Ellipsometry and spectrophotometry yield a compositional trend for the experimental optical band gap comparable with our predictions: a quick decrease from 7.94 eV for pure SiO2 to 3.91 eV at x =0.15 , followed by a much slower decrease over the rest of the composition range ending at 3.26 eV for pure TiO2. A detailed analysis of anatase and rutile-based solid solutions reveals the introduction of silicon-induced oxygen states into the band gap in the TiO2-rich composition region, which results in the predicted reduction of the band gap. However, we show that the optical absorption of those states is negligible. We have obtained good agreement between the calculated and measured imaginary part of the dielectric function ɛi, especially for the TiO2-rich compositions. Finally, we predict an almost-linear refractive index change at 632.8 nm between a-SiO2 (1.36) and a-TiO2 (2.34), which was experimentally confirmed.

  2. Effect of High Configuration Entropy and Rare Earth Addition on Boride Precipitation and Mechanical Properties of Multi-principal-Element Alloys

    Science.gov (United States)

    Zhang, H.; Zhong, X. C.; He, Y. Z.; Li, W. H.; Wu, W. F.; Chen, G.; Guo, S.

    2017-08-01

    A series of multi-principal-element (MPE) alloys have been prepared by adding Ni, Mn, Al, Cu and Y into the reference CoCrFe-B alloy. The microstructure and mechanical properties of these MPE alloys have been investigated thoroughly. It is found that the addition of the elements can inhibit boride precipitation in the designed alloys and the solid solution strengthening effect induced by interstitial boron atoms is more significant than that by boride precipitation. The MPE alloys with the fcc phase as the main solid solution phase have a higher boron solubility and hence less boride precipitation, than those with the bcc phase as the main solid solution phase. The addition of yttrium can improve the boron solubility, decrease boride precipitation, control the boride morphology and, importantly, simultaneously improve the compressive strength and ductility of boron-containing MPE alloys.

  3. A facile and rapid room-temperature route to hierarchical bismuth oxyhalide solid solutions with composition-dependent photocatalytic activity.

    Science.gov (United States)

    Zhang, Juan; Han, Qiaofeng; Zhu, Junwu; Wang, Xin

    2016-09-01

    The unique nanosheet-based flower-like BiOCl1-xBrx (x=0-1) hierarchical solid solutions have been prepared by the reaction of Bi2O3 and KCl/KBr in mixed solution of glacial acetic acid (HAc) and H2O in dozens of minutes under ambient conditions. During the preparation process, the intermediate bismuth oxide acetate (CH3COOBiO) plays a key role in the formation of BiOCl1-xBrx solid solutions in such a short time. The as-prepared hierarchical BiOCl1-xBrx solid solutions possess high specific surface areas and modified band structures, which exhibit enhanced photocatalytic activity for Rhodamine B (RhB) degradation in comparison with pure BiOCl and BiOBr under visible light irradiation, with the activity reaching the maximum at x=0.5. The photodegradation efficiency of the BiOCl0.5Br0.5 solid solution is twice and 12times higher than P25 TiO2 under UV and visible light irradiation, respectively. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Formation of a 25 mol% Fe2O3-Al2O3 solid solution prepared by ball milling

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Mørup, Steen; Linderoth, Søren

    1996-01-01

    The phase transformation process of a 25 mol% Fe2O3-Al2O3 powder mixture during high-energy ball milling has been studied by x-ray diffraction and Mossbauer spectroscopy. A metastable solid solution of 25 mol % Fe2O3 in Al2O3 with corundum structure has successfully been prepared after a milling...

  5. STRUCTURAL AND DYNAMIC PROPERTIES OF SOLID-SOLUTIONS OF BAF2 AND GDF3 - AN EPR STUDY

    NARCIS (Netherlands)

    DENHARTOG, HW

    Results of EPR experiments on solid solutions of barium and gadolinium fluoride in the temperature range 300 to 900 K are presented. At room temperature the Gd-ions are located predominantly at trigonal sites. If the temperature is increased, the interstitial fluoride ions are found to dissociate

  6. Quinary wurtzite Zn-Ga-Ge-N-O solid solutions and their photocatalytic properties under visible light irradiation.

    Science.gov (United States)

    Xie, Yinghao; Wu, Fangfang; Sun, Xiaoqin; Chen, Hongmei; Lv, Meilin; Ni, Shuang; Liu, Gang; Xu, Xiaoxiang

    2016-01-12

    Wurtzite solid solutions between GaN and ZnO highlight an intriguing paradigm for water splitting into hydrogen and oxygen using solar energy. However, large composition discrepancy often occurs inside the compound owing to the volatile nature of Zn, thereby prescribing rigorous terms on synthetic conditions. Here we demonstrate the merits of constituting quinary Zn-Ga-Ge-N-O solid solutions by introducing Ge into the wurtzite framework. The presence of Ge not only mitigates the vaporization of Zn but also strongly promotes particle crystallization. Synthetic details for these quinary compounds were systematically explored and their photocatalytic properties were thoroughly investigated. Proper starting molar ratios of Zn/Ga/Ge are of primary importance for single phase formation, high particle crystallinity and good photocatalytic performance. Efficient photocatalytic hydrogen and oxygen production from water were achieved for these quinary solid solutions which is strongly correlated with Ge content in the structure. Apparent quantum efficiency for optimized sample approaches 1.01% for hydrogen production and 1.14% for oxygen production. Theoretical calculation reveals the critical role of Zn for the band gap reduction in these solid solutions and their superior photocatalytic acitivity can be understood by the preservation of Zn in the structure as well as a good crystallinity after introducing Ge.

  7. Solid solutions of gadolinium doped zinc oxide nanorods by combined microwave-ultrasonic irradiation assisted crystallization

    Science.gov (United States)

    Kiani, Armin; Dastafkan, Kamran; Obeydavi, Ali; Rahimi, Mohammad

    2017-12-01

    Nanocrystalline solid solutions consisting of un-doped and gadolinium doped zinc oxide nanorods were fabricated by a modified sol-gel process utilizing combined ultrasonic-microwave irradiations. Polyvinylpyrrolidone, diethylene glycol, and triethylenetetramine respectively as capping, structure directing, and complexing agents were used under ultrasound dynamic aging and microwave heating to obtain crystalline nanorods. Crystalline phase monitoring, lattice parameters and variation, morphology and shape, elemental analysis, functional groups, reducibility, and the oxidation state of emerged species were examined by PXRD, FESEM, TEM, EDX, FTIR, micro Raman, H2-TPR, and EPR techniques. Results have verified that irradiation mechanism of gelation and crystallization reduces the reaction time, augments the crystal quality, and formation of hexagonal close pack structure of Wurtzite morphology. Besides, dissolution of gadolinium within host lattice involves lattice deformation, unit cell distortion, and angular position variation. Structure related shape and growth along with compositional purity were observed through microscopic and spectroscopic surveys. Furthermore, TPR and EPR studies elucidated more detailed behavior upon exposure to the exerted irradiations and subsequent air-annealing including the formed oxidation states and electron trapping centers, presence of gadolinium, zinc, and oxygen disarrays and defects, as well as alteration in the host unit cell via gadolinium addition.

  8. Understanding the defect chemistry of alkali metal strontium silicate solid solutions: insights from experiment and theory

    KAUST Repository

    Bayliss, Ryan D.

    2014-09-24

    © the Partner Organisations 2014. Recent reports of remarkably high oxide ion conduction in a new family of strontium silicates have been challenged. It has recently been demonstrated that, in the nominally potassium substituted strontium germanium silicate material, the dominant charge carrier was not the oxygen ion, and furthermore that the material was not single phase (R. D. Bayliss et. al., Energy Environ. Sci., 2014, DOI: 10.1039/c4ee00734d). In this work we re-investigate the sodium-doped strontium silicate material that was reported to exhibit the highest oxide ion conductivity in the solid solution, nominally Sr0.55Na0.45SiO2.775. The results show lower levels of total conductivity than previously reported and sub-micron elemental mapping demonstrates, in a similar manner to that reported for the Sr0.8K0.2Si0.5Ge0.5O2.9 composition, an inhomogeneous chemical distribution correlating with a multiphase material. It is also shown that the conductivity is not related to protonic mobility. A density functional theory computational approach provides a theoretical justification for these new results, related to the high energetic costs associated with oxygen vacancy formation. This journal is

  9. Long-lived non-equilibrium interstitial solid solutions in binary mixtures

    Science.gov (United States)

    Ríos de Anda, Ioatzin; Turci, Francesco; Sear, Richard P.; Royall, C. Patrick

    2017-09-01

    We perform particle resolved experimental studies on the heterogeneous crystallisation process of two component mixtures of hard spheres. The components have a size ratio of 0.39. We compared these with molecular dynamics simulations of homogenous nucleation. We find for both experiments and simulations that the final assemblies are interstitial solid solutions, where the large particles form crystalline close-packed lattices, whereas the small particles occupy random interstitial sites. This interstitial solution resembles that found at equilibrium when the size ratios are 0.3 [L. Filion et al., Phys. Rev. Lett. 107, 168302 (2011)] and 0.4 [L. Filion, Ph.D. thesis, Utrecht University, 2011]. However, unlike these previous studies, for our system simulations showed that the small particles are trapped in the octahedral holes of the ordered structure formed by the large particles, leading to long-lived non-equilibrium structures in the time scales studied and not the equilibrium interstitial solutions found earlier. Interestingly, the percentage of small particles in the crystal formed by the large ones rapidly reaches a maximum of ˜14% for most of the packing fractions tested, unlike previous predictions where the occupancy of the interstitial sites increases with the system concentration. Finally, no further hopping of the small particles was observed.

  10. The Diffusion Coefficients Of Cu And Zn In amp913- And amp919- Solid Solutions

    Directory of Open Access Journals (Sweden)

    Adhurim Hoxha

    2015-06-01

    Full Text Available Abstract In this work the multiphase diffusion in the infinite couple Cu-Zn was studied experimentally. The diffusion couples were prepared by platting technique. The samples were annealed in three different temperatures which were taken below the melting temperature of Zn. For each temperature there were used six different annealing times ranging from 1h up to 32h. In the micrographs provided by light microscopy it can be seen the formation of only two of the three intermetalic phases present in the Cu-Zn phase diagram namely amp949- and amp947-phase. WDX EPMA analysis was used to obtain the concentration profiles of the diffusion layers.he diffusion coefficients of Cu and Zn in amp945- and amp951-solid solutions are calculated using the solutions of second Ficks law for independent concentration case. Since the diffusion coefficients depends only on the temperature of annealing and not on the time of it they must be the same for a given temperature. Therefore the diffusion coefficients were averaged for each temperature. Knowing the diffusion coefficients for each temperature enables the calculation of the activation energies and the frequency factors as well.

  11. Slow dynamics and field-induced transitions in a mixed-valence oxide solid solution

    Science.gov (United States)

    Charilaou, M.; Löffler, J. F.; Gehring, A. U.

    2011-06-01

    In this study, the spin-glass-like properties of (x)FeTiO3-(1-x)Fe2O3, with x =0.8 and 0.9, as prominent mixed-valence state solid solution, were investigated by means of ac susceptibility and dc magnetization measurements. Dynamic ac susceptibility indicates freezing at finite temperature Tf, obeying a power law with a dynamic exponent zν≈7, close to that of the 3D Ising spin glass, and relaxation rates in the kHz range. The slow dynamics are explained by the presence of ordered superspins, whose relaxation rate decreases with increasing superspin size. In the frozen state, symmetry breaking is observed at a critical field Hcr which decreases with temperature obeying a power law Hcr2/3∝T, and is followed by a metamagnetic transition with increasing field similar to that of the end-member FeTiO3, obeying a Hcr3/2∝T law. The two transitions converge near the freezing temperature, thus denoting the H-T phase diagram of the system.

  12. Long-lived non-equilibrium interstitial solid solutions in binary mixtures.

    Science.gov (United States)

    Ríos de Anda, Ioatzin; Turci, Francesco; Sear, Richard P; Royall, C Patrick

    2017-09-28

    We perform particle resolved experimental studies on the heterogeneous crystallisation process of two component mixtures of hard spheres. The components have a size ratio of 0.39. We compared these with molecular dynamics simulations of homogenous nucleation. We find for both experiments and simulations that the final assemblies are interstitial solid solutions, where the large particles form crystalline close-packed lattices, whereas the small particles occupy random interstitial sites. This interstitial solution resembles that found at equilibrium when the size ratios are 0.3 [L. Filion et al., Phys. Rev. Lett. 107, 168302 (2011)] and 0.4 [L. Filion, Ph.D. thesis, Utrecht University, 2011]. However, unlike these previous studies, for our system simulations showed that the small particles are trapped in the octahedral holes of the ordered structure formed by the large particles, leading to long-lived non-equilibrium structures in the time scales studied and not the equilibrium interstitial solutions found earlier. Interestingly, the percentage of small particles in the crystal formed by the large ones rapidly reaches a maximum of ∼14% for most of the packing fractions tested, unlike previous predictions where the occupancy of the interstitial sites increases with the system concentration. Finally, no further hopping of the small particles was observed.

  13. Preparation and characterization of Bi4–xPrxTi3O12 solid solutions

    Directory of Open Access Journals (Sweden)

    A. I. Klyndyuk

    2017-12-01

    Full Text Available The Bi4–xPrxTi3O12 (BPT solid solutions (x = 0.05, 0.10, 0.15 with small praseodymium content were prepared by solid-state method. Thermal, electric, and dielectric properties of BPT were studied. It was revealed that BPT titanates crystalize in аn orthorhombic structure and exhibit p-type semiconductivity. Dielectric constant of BPT increased, Curie temperature (TC, electrical conductivity and dielectric losses decreased, but lattice parameters and thermo-EMF coefficient remained practically unchanged with the increase of praseodymium content in layered Bi4–xPrxTi3O12. It was determined that activation energy of direct current (DC electrical conductivity and linear thermal expansion coefficient (LTEC of BPT changes at ferroelectric (FE → paraelectric (PE phase transition. The activation energy and LTEC changed below and above TC from 1.08–1.56 eV to 0.45–0.86 eV and from (9.10–10.80×10–6 K–1 to (13.12-14.61×10–6 K–1, respectively. The AC electrical conductivity studies of BPT illustrated short-range order with ionic translations assisted by small-polaron hopping.

  14. Structural, thermal and magnetic investigations on immiscible Ag–Co nanocrystalline alloy with addition of Mn

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, B.N., E-mail: bholanath_mondal@yahoo.co.in [Department of Central Scientific Services, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India); Chabri, S. [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711 103 (India); Sardar, G. [Department of Zoology, Baruipur College, South 24 Parganas 743610 (India); Nath, D.N. [Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India); Chattopadhyay, P.P. [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711 103 (India)

    2016-08-15

    50Ag–50Co (at%) and 40Ag–40Co–20Mn (at%) alloys prepared by ball milling up to 50 h and subsequent isothermal annealing at the temperature range of 350–650 °C for 1 h has been investigated systematically. Mn promotes early formation of the nanostructures and solid solutions of the alloys by ball milling. In contrast, annealing at 350 °C of Ag–Co alloy resulted the dissolution of hcp Co. Annealing above 350 °C decomposes the metastable Ag–Co alloy into the polycrystalline and segregated Ag and fcc Co. Enthalpy of mixing of both the alloy has increased with increase in milling time. Both the nanocrystalline alloys prepared by ball milling and annealing have been revealed the ferromagnetic behavior. The most significant improvement of magnetic properties is yielded in as-milled Ag–Co–Mn alloy obtained after annealing at 550 °C for 1 h. - Highlights: • A complete solid solution of Ag–Co–Mn alloy obtained after 50 h of milling. • A complete solid solution of milled Ag–Co alloy forms annealed at 350 {sup °}C for 1 h. • Precipitation of fcc Co are observed after annealing above 350 °C. • Enthalpy of mixing of the alloys increased with increase in milling time. • The superior magnetic properties achieved of Ag–Co–Mn alloy annealed at 550 °C.

  15. Effect of nitrogen on iron-manganese-based shape memory alloys

    Science.gov (United States)

    Ariapour, Azita

    Shape memory effect is due to a reversible martensitic transformation. The major drawback in case of Fe-Mn-based shape memory alloys is their inferior shape memory effect compared to Ni-Ti and Cu-based shape memory alloys and their low strength and corrosion resistance compared to steel alloys. It is known that by increasing the alloy strength the shape memory effect can be improved. Nitrogen in solid solution can increase the strength of steels to a greater extent than other major alloying elements. However, its effect on shape memory effect of Fe-Mn-based alloys is ambiguous. In this work first we investigated the effect of nitrogen addition in solid solution on both shape memory effect (SME) and strength of a Fe-Mn-Cr-Ni-Si shape memory alloy (SMA). It was found that interstitial nitrogen suppressed the shape memory effect in these alloys. As an example addition of 0.24 wt % nitrogen in solid solution to the alloy system suppressed the SME by ˜80% and increased the strength by 20%. A reduction of martensitic phase formation was found to be the dominant factor in suppression of the SME. This was related, experimentally and theoretically to stacking fault energy of the alloy as well as the driving force and friction force during the transformation. The second approach was doping the alloy with both 0.36 wt% of nitrogen and 0.36 wt% of niobium. Niobium has great affinity for nitrogen and thus NbN dispersed particles can be produced in the alloy following hot rolling. Then particles prevent growth of the alloy and increase the strength of the alloy due to reduced grain size, and precipitation hardening. The improvement of SME in this alloy compared to the interstitial containing alloys was due to the large removal of the nitrogen from solid solution. In case of all the alloys studied in this work, the presence of nitrogen in solid solution improved the corrosion resistance of the alloy. This suggests that nitrogen can replace nickel in the alloy. One of the

  16. The role of the alloy matrix in the creep behavior of particle-strengthened alloys

    Science.gov (United States)

    Ajaja, O.; Howson, T. E.; Purushothaman, S.; Tien, J. K.

    1980-01-01

    The strengthening microstructural features in heat-resistant super-alloys are oxide dispersoids and/or gamma-prime precipitates. The role of the strength of the alloy matrix in the creep resistance of these alloys is considered. An evaluation was made of experimental data on oxide-dispersion- and/or precipitation-strengthened nickel-based alloys with various levels of matrix solid solution strengthening; a generalized expression for creep rates which separates the matrix contributions from the particle contributions to the resisting stress and creep strength of these alloys was derived. It is concluded that the major role of the alloy matrix in the creep behavior of these alloys is in determining the apparent stress dependence of the creep rates.

  17. Synthesis and photocatalytic oxidation of different organic dyes by using Mn 2O 3/TiO 2 solid solution and visible light

    Science.gov (United States)

    Ghorai, Tanmay K.; Pramanik, Susmita; Pramanik, Panchanan

    2009-08-01

    Mn 2O 3/TiO 2 solid solution was prepared from two different oxides, manganese oxide (from KMnO 4 and ethanol) and TiO 2, these samples were characterized by BET, XRD, EDAX, SEM, FT-IR, ESR, XPS and UV-vis absorption spectroscopy. Photocatalytic activities of Mn 2O 3/TiO 2 powder was investigated by photooxidation of different dyes like Rhodamine B, thymol blue, methyl orange and Bromocresol green under visible light (300-W Xe lamp; λ > 420 nm). The results show that the alloy of TiO 2 with 1 mol% of Mn 2O 3 (MNT1) exhibit photocatalytic activity 3-5 times higher than that of P25 TiO 2 for oxidation of various dyes (RB, TB, MO and BG). The average particle size and crystallite size of MNT1 were found to be 100 nm and 12 nm measured from SEM and XRD, respectively. The EPR spectra of the Mn 2O 3/TiO 2 samples is a sharp five-line Mn(III) component centered on geff = 1 .99.

  18. Calculation of thermodynamic functions of saturated solid solution of AgIn2Te3I compound in the Ag–In–Te–I system

    Directory of Open Access Journals (Sweden)

    Moroz Mykola

    2017-01-01

    Full Text Available Triangulation of Ag–In–Te–I system in the vicinity of AgIn2Te3I compound was investigated by X-ray diffraction and differential thermal analysis methods. The spatial position of the phase region AgIn2Te3I–InTe–Ag2Te–AgI regarding the figurative point of silver was used in order to write the equation of virtual potential-forming reaction. Potential-forming reaction was performed in electrochemical cell (ECC of the type (– C | Ag | Ag3GeS3I(Br glass | D | C (+ where C are inert (graphite electrodes; Ag and D are the electrodes of the ECC; D represents the alloy of four-phase region; Ag3GeS3I glass is a membrane with purely ionic Ag+ conductivity. Linear dependence of the EMF of cell on temperature in the range of 440−480 К was used to calculate the standard thermodynamic functions of saturated solid solution of AgIn2Te3I compound in Ag–In–Te–I system.

  19. Calculation of thermodynamic functions of saturated solid solution of AgIn2Te3I compound in the Ag-In-Te-I system

    Science.gov (United States)

    Moroz, Mykola; Prokhorenko, Sergiy; Prokhorenko, Myroslava; Reshetnyak, Oleksandr

    2017-01-01

    Triangulation of Ag-In-Te-I system in the vicinity of AgIn2Te3I compound was investigated by X-ray diffraction and differential thermal analysis methods. The spatial position of the phase region AgIn2Te3I-InTe-Ag2Te-AgI regarding the figurative point of silver was used in order to write the equation of virtual potential-forming reaction. Potential-forming reaction was performed in electrochemical cell (ECC) of the type (-) C | Ag | Ag3GeS3I(Br) glass | D | C (+) where C are inert (graphite) electrodes; Ag and D are the electrodes of the ECC; D represents the alloy of four-phase region; Ag3GeS3I glass is a membrane with purely ionic Ag+ conductivity). Linear dependence of the EMF of cell on temperature in the range of 440-480 K was used to calculate the standard thermodynamic functions of saturated solid solution of AgIn2Te3I compound in Ag-In-Te-I system.

  20. A comparative structure and morphology study of Zn (1- x ) Cd x O solid solution grown on ZnO and different sapphire orientations

    Science.gov (United States)

    Fouzri, A.; Sallet, V.; Oumezzine, M.

    2011-09-01

    Zn (1- x) Cd xO solid solutions with a constant Cadmium flow 10 cc have been grown on ZnO, c-, a- and r-plane sapphire substrates using metal organic chemical vapor deposition (MO-CVD). The optical transmission spectra and energy band-gap equation established by Mikano et al. were used to estimate cadmium mole fraction of alloy. Lattice parameters and morphology of these films were examined using high resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) as Cd incorporation and employed substrate. By comparison, we observe significant differences between Cd incorporation and morphologies depending on nature and substrate orientation but the hexagonal wurtzite structure is maintained. Higher Cd incorporation (11.2 at%) is obtained on Zn (1- x) Cd xO grown on r-plane sapphire, which is confirmed by the greatest energy shift (340 meV) to lower energy measured by room temperature photoluminescence. However, the lattice parameter c remains unchanged while parameter a is identical for films deposited on ZnO and r-plane sapphire substrates and for those deposited on c- and a-plane sapphire substrates.

  1. Dispersoid reinforced alloy powder and method of making

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Iver E.; Terpstra, Robert L.

    2017-12-05

    A method of making dispersion-strengthened alloy particles involves melting an alloy having a corrosion and/or oxidation resistance-imparting alloying element, a dispersoid-forming element, and a matrix metal wherein the dispersoid-forming element exhibits a greater tendency to react with a reactive species acquired from an atomizing gas than does the alloying element. The melted alloy is atomized with the atomizing gas including the reactive species to form atomized particles so that the reactive species is (a) dissolved in solid solution to a depth below the surface of atomized particles and/or (b) reacted with the dispersoid-forming element to form dispersoids in the atomized particles to a depth below the surface of said atomized particles. The atomized alloy particles are solidified as solidified alloy particles or as a solidified deposit of alloy particles. Bodies made from the dispersion strengthened alloy particles, deposit thereof, exhibit enhanced fatigue and creep resistance and reduced wear as well as enhanced corrosion and/or oxidation resistance at high temperatures by virtue of the presence of the corrosion and/or oxidation resistance imparting alloying element in solid solution in the particle alloy matrix.

  2. Dispersoid reinforced alloy powder and method of making

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Iver E.; Terpstra, Robert L.

    2017-10-10

    A method of making dispersion-strengthened alloy particles involves melting an alloy having a corrosion and/or oxidation resistance-imparting alloying element, a dispersoid-forming element, and a matrix metal wherein the dispersoid-forming element exhibits a greater tendency to react with a reactive species acquired from an atomizing gas than does the alloying element. The melted alloy is atomized with the atomizing gas including the reactive species to form atomized particles so that the reactive species is (a) dissolved in solid solution to a depth below the surface of atomized particles and/or (b) reacted with the dispersoid-forming element to form dispersoids in the atomized particles to a depth below the surface of said atomized particles. The atomized alloy particles are solidified as solidified alloy particles or as a solidified deposit of alloy particles. Bodies made from the dispersion strengthened alloy particles, deposit thereof, exhibit enhanced fatigue and creep resistance and reduced wear as well as enhanced corrosion and/or oxidation resistance at high temperatures by virtue of the presence of the corrosion and/or oxidation resistance imparting alloying element in solid solution in the particle alloy matrix.

  3. The effect of solid solution treatment on the hardness and microstructure of 0.6%wt C-10.8%wt Mn-1.44%wt Cr austenitic manganese steel

    Science.gov (United States)

    Nurjaman, F.; Bahfie, F.; Astuti, W.; Shofi, A.

    2017-04-01

    Austenitic manganese steel is steel alloy that has high manganese content (10-14%wt Mn). The characteristics of austenitic manganese steel are good in toughness, ductility, and wear resistance. Effect of solid solution treatment on the hardness and microstructure of austenitic manganese steel was studied in this experiment. The solid solution treatment process of austenitic manganese steel, 0.6%wt C-10.8%wt Mn-1.44%wt Cr, was conducted by heating the material at varied temperatures (950°C, 1000°C, 1050°C) for an hour and then quenching it in two different quenching media, i.e. oil and water. Further, the samples were tempered at three different temperatures (300°C, 400°C, and 500°C) for 2 hours. The treated materials were analyzed by Rockwell Hardness Tester to obtain the information of materials hardness and by an optical microscope and XRD to investigate the microstructure phase of the treated materials. Heating the austenitic manganese steel at 950°C for an hour followed by water quenching dissolved all carbide in as-cast condition and resulted the fully austenitic on its microstructure. Carbide precipitation occurred due to the prolongation of soaking time in solid solution treatment and tempering process. The optimum hardness of sample was 53.3 HRC, which was resulted by heating this material until 1000°C for an hour, followed by water quenching and tempering at 400°C for 2 hours.

  4. Study of metal--oxygen solid solutions utilizing solid electrolytic cells

    Energy Technology Data Exchange (ETDEWEB)

    Lauf, Robert John [Univ. of Illinois, Urbana-Champaign, IL (United States)

    1978-10-01

    A study was made of the thermodynamic and kinetic behavior of oxygen in a number of Group V metals and alloys. Investigations were made with a ThO2Y2O3 electrolyte over the temperature range of 600 to 1150°to 1423°K). The activity of oxygen in three Nb--Ta alloys (nominally 25, 50, and 75 at. % Ta) was found to obey Henry's Law up to the solubility limit in each alloy. The standard entropy and enthalpy of solution of oxygen in the three Nb--Ta alloys were intermediate between those for pure niobium and pure tantalum, and varied almost linearly with Nb : Ta content. The diffusion coefficient of oxygen was measured in niobium and vanadium, and the values were found to be in excellent agreement with literature values obtained by a variety of techniques. The diffusion coefficient of oxygen in each of several dilute substitutional niobium alloys was measured and compared to the diffusion coefficient in pure niobium. The addition of 1 to 5% substitutional solutes resulted in as much as an order-of-magnitude decrease in the oxygen diffusivity. This decrease is believed to be due to trapping of oxygen by substitutional solute atoms. The substitutional-oxygen binding or ''trap'' energies (in eV) for several substitutional solutes in niobium were determined to be: Ta: 0.3 ± 0.1; V: 0.55 ± 0.05; Ti: 0.7 ± 0.1; Zr: 0.7 ± 0.05. The trap energy is rationalized as being the sum of a chemical interaction and an elastic interaction. 27 figures, 9 tables.

  5. Raman and Fourier transform infrared spectroscopic study of pyromorphite-vanadinite solid solutions

    Science.gov (United States)

    Solecka, Urszula; Bajda, Tomasz; Topolska, Justyna; Zelek-Pogudz, Sylwia; Manecki, Maciej

    2018-02-01

    Due to the great range of the application fields for apatites, there is a strong need to complete the data set determining the properties of these minerals. In this study, Raman and Infrared spectra of the phases from pyromorphite Pb5(PO4)3Cl - vanadinite Pb5(VO4)3Cl series were investigated. Totally, 9 samples (2 end-members and 7 solid solutions of the series) were synthesized at 25 °C and pH = 3.5, and analyzed. In the Raman and Infrared spectra of the studied Pb-apatites, the bands typical for the vibrations in the PO4 and the VO4 tetrahedra appeared. The bands attributed to the stretching vibrations (ν1, ν3) occurred in the 1050-910 cm- 1 and 830-720 cm- 1 regions, whereas the bending vibrations (ν2, ν4) were visible at the 580-540 cm- 1, 430-380 cm- 1 and 370-290 cm- 1 range. The position of the bands depended on the P/(P + V) ratio in the analyzed solid, since there are differences in the ionic radii and the atomic mass of P5 + and V5 +, which affect the bong lengths, bond forces and the banding energies of the substituting tetrahedra. The analysis allowed observing gradual shifts of the bands caused by the replacement of phosphorous with vanadium in the studied phases. The positions and the intensities of selected bands are proposed to serve as a semi-quantitative estimation of the chemical composition of the phases from the pyromorphite - vanadinite series.

  6. Nonequilibrium Phase Chemistry in High Temperature Structure Alloys

    Science.gov (United States)

    Wang, R.

    1991-01-01

    Titanium and nickel aluminides of nonequilibrium microstructures and in thin gauge thickness were identified, characterized and produced for potential high temperature applications. A high rate sputter deposition technique for rapid surveillance of the microstructures and nonequilibrium phase is demonstrated. Alloys with specific compositions were synthesized with extended solid solutions, stable dispersoids, and specific phase boundaries associated with different heat treatments. Phase stability and mechanical behavior of these nonequilibrium alloys were investigated and compared.

  7. Thermoelectric and Transport Properties of N-Type Bi{sub 2−x}Sb{sub x}Te{sub 3−y}Se{sub y} Solid Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Eum, A-Young; Kim, Il-Ho [Korea National University of Transportation, Chungju (Korea, Republic of)

    2017-03-15

    Bi{sub 2−x}Sb{sub x}Te{sub 3−y}Se{sub y} (x = 0.1, 0.2 and y = 0.15, 0.3) solid solutions were prepared using encapsulated melting and hot pressing. The lattice constants decreased with increases in the Sb and the Se contents, which revealed the successful formation of solid solutions. The relative densities of the hot-pressed specimens were 95 - 98%. All specimens exhibited n-type conduction at temperatures from 323 K to 523 K, and the electrical conductivity slightly decreased with increasing temperature. With an increase in the Se content, the Seebeck coefficient increased while the electrical and the thermal conductivities decreased; thus, the dimensionless figure of merit could be improved. The maximum dimensionless figure of merit ZT{sub max} = 0.89 was obtained at 423 K for Bi{sub 1.8}Sb{sub 0.2}Te{sub 2.7}Se{sub 0.3}. An increase in the Sb content resulted in a decrease in the lattice thermal conductivity because of an increase in alloy scattering, but its effect on the electrical properties was not superior to the effect of Se substitution. Therefore, Sb substitution could effectively control the thermal properties while Se substitution could effectively control the electrical properties.

  8. Improving the electrocatalytic properties of Pd-based catalyst for direct alcohol fuel cells: effect of solid solution.

    Science.gov (United States)

    Wen, Cuilian; Wei, Ying; Tang, Dian; Sa, Baisheng; Zhang, Teng; Chen, Changxin

    2017-07-07

    The tolerance of the electrode against the CO species absorbed upon the surface presents the biggest dilemma of the alcohol fuel cells. Here we report for the first time that the inclusion of (Zr, Ce)O2 solid solution as the supporting material can significantly improve the anti-CO-poisoning as well as the activity of Pd/C catalyst for ethylene glycol electro-oxidation in KOH medium. In particular, the physical origin of the improved electrocatalytic properties has been unraveled by first principle calculations. The 3D stereoscopic Pd cluster on the surface of (Zr, Ce)O2 solid solution leads to weaker Pd-C bonding and smaller CO desorption driving force. These results support that the Pd/ZrO2-CeO2/C composite catalyst could be used as a promising effective candidate for direct alcohol fuel cells application.

  9. High-temperature, Knudsen cell-mass spectroscopic studies on lanthanum oxide/uranium dioxide solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Sunder, S.; McEachern, R.; LeBlanc, J.C

    2001-07-01

    Knudsen cell-mass spectroscopic experiments were carried out with lanthanum oxide/uranium oxide solid solutions (1%, 2% and 5% (metal at.% basis)) to assess the volatilization characteristics of rare earths present in irradiated nuclear fuel. The oxidation state of each sample used was conditioned to the 'uranium dioxide stage' by heating in the Knudsen cell under an atmosphere of 10% C0{sub 2} in CO. The mass spectra were analyzed to obtain the vapour pressures of the lanthanum and uranium species. It was found that the vapour pressure of lanthanum oxide follows Henry's law, i.e., its value is directly proportional to its concentration in the solid phase. Also, the vapour pressure of lanthanum oxide over the solid solution, after correction for its concentration in the solid phase, is similar to that of uranium dioxide. (author)

  10. Optical and Piezoelectric Study of KNN Solid Solutions Co-Doped with La-Mn and Eu-Fe

    Directory of Open Access Journals (Sweden)

    Jesús-Alejandro Peña-Jiménez

    2016-09-01

    Full Text Available The solid-state method was used to synthesize single phase potassium-sodium niobate (KNN co-doped with the La3+–Mn4+ and Eu3+–Fe3+ ion pairs. Structural determination of all studied solid solutions was accomplished by XRD and Rietveld refinement method. Electron paramagnetic resonance (EPR studies were performed to determine the oxidation state of paramagnetic centers. Optical spectroscopy measurements, excitation, emission and decay lifetime were carried out for each solid solution. The present study reveals that doping KNN with La3+–Mn4+ and Eu3+–Fe3+ at concentrations of 0.5 mol % and 1 mol %, respectively, improves the ferroelectric and piezoelectric behavior and induce the generation of optical properties in the material for potential applications.

  11. Solid Solution Effects on the MgAl2O4-MgGa2O4 System

    Energy Technology Data Exchange (ETDEWEB)

    O' Hara, Kelley [University of Missouri, Rolla; Smith, Jeffrey D [ORNL; Hemrick, James Gordon [ORNL

    2009-01-01

    Phase relations between two spinel compounds (MgAl2O4 and MgGa2O4) were studied. Stoichiometric MgAl2O4 was formed in the laboratory through a coprecipitation method. Complete solid solution formation int eh MgAl2O4-MgGa2O4 systems was confirmed through X-ray diffraction analysis. Solid solution between MgAl2O4-MgGa2O4 decreases thermal conductivity at all temperatures up to 900oC. At 200oC with 10 mol% additoin of MgGa2O4 thermal conductivity decreases approximately 25%, and at 900oC there was still an 8% decrease. Additionally, preliminary studies show that porosity between 5% and 10% does not have an appreciable effect on the thermal conductivity in this study.

  12. From solid solution to cluster formation of Fe and Cr in α-Zr

    Energy Technology Data Exchange (ETDEWEB)

    Burr, P.A., E-mail: burr.patrick@gmail.com [Centre for Nuclear Engineering and Department of Materials, Imperial College London, London, SW7 2AZ (United Kingdom); Institute of Materials Engineering, Australian Nuclear Science & Technology Organisation, Menai, New South Wales 2234 (Australia); Wenman, M.R. [Centre for Nuclear Engineering and Department of Materials, Imperial College London, London, SW7 2AZ (United Kingdom); Gault, B.; Moody, M.P. [Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH (United Kingdom); Ivermark, M. [High Temperature Materials, Sandvik Materials Technology, 734 27 Hallstahammar (Sweden); University of Manchester, School of Materials, M13 9PL (United Kingdom); Rushton, M.J.D. [Centre for Nuclear Engineering and Department of Materials, Imperial College London, London, SW7 2AZ (United Kingdom); Preuss, M. [University of Manchester, School of Materials, M13 9PL (United Kingdom); Edwards, L. [Institute of Materials Engineering, Australian Nuclear Science & Technology Organisation, Menai, New South Wales 2234 (Australia); Grimes, R.W. [Centre for Nuclear Engineering and Department of Materials, Imperial College London, London, SW7 2AZ (United Kingdom)

    2015-12-15

    To understand the mechanisms by which the re-solution of Fe and Cr additions increase the corrosion rate of irradiated Zr alloys, the solubility and clustering of Fe and Cr in model binary Zr alloys was investigated using a combination of experimental and modelling techniques — atom probe tomography (APT), x-ray diffraction (XRD), thermoelectric power (TEP) and density functional theory (DFT). Cr occupies both interstitial and substitutional sites in the α-Zr lattice; Fe favours interstitial sites, and a low-symmetry site that was not previously modelled is found to be the most favourable for Fe. Lattice expansion as a function of Fe and Cr content in the α-Zr matrix deviates from Vegard's law and is strongly anisotropic for Fe additions, expanding the c-axis while contracting the a-axis. Matrix content of solutes cannot be reliably estimated from lattice parameter measurements, instead a combination of TEP and APT was employed. Defect clusters form at higher solution concentrations, which induce a smaller lattice strain compared to the dilute defects. In the presence of a Zr vacancy, all two-atom clusters are more soluble than individual point defects and as many as four Fe or three Cr atoms could be accommodated in a single Zr vacancy. The Zr vacancy is critical for the increased apparent solubility of defect clusters; the implications for irradiation induced microstructure changes in Zr alloys are discussed.

  13. Influence of Ce0⋅68Zr0⋅32O2 solid solution on depositing γ ...

    Indian Academy of Sciences (India)

    Unknown

    FeCrAl covered with 1# slurry composing of only γ-Al2O3 is more than that of other three slurries, when thermal shock test and aging treatment were made, viz. Ce0⋅68Zr0⋅32O2 solid solution can improve the bonding between γ-Al2O3-. Figure 1. Morphologies of metallic foils: (a) untreated and. (b) pretreated at 950°C for ...

  14. Effect of Heat-Treatment and Composition on Structure and Luminescence Properties of Spinel-Type Solid Solution Nanocrystals.

    Science.gov (United States)

    Sakoda, Kazuki; Hirano, Masanori

    2015-08-01

    The compositional dependence of the structure and properties of spinel-type solid solutions, Zn(A,Ga)2O4 was investigated by comparison with samples hydrothermally prepared and those after heat treatment at 1000 °C in air. Nanocrystalline spinel-type solid solutions in the whole composition range in the ZnAl2O4-ZnGa2O4 system were directly formed from the aqueous precursor solutions of ZnSO4, Al(NO3)3 and Ga(NO3)3 under hydrothermal conditions at 180 °C for 5 h in the presence of tetramethylammonium hydroxide. The incorporation of aluminum into the lattice, Zn(AlxGa1-x)2O4, resulted in lower crystallinity of the spinel. The relationship between the lattice parameter of as-prepared samples and the Al atomic ratio in the spinel composition was slightly apart from the ideal linear relationship that was obtained in the samples after heat treatment at 1000 °C. The optical band gap of both as-prepared solid solutions and those heat treated linearly increased from 4.1~4.2 to 5.25 eV by the incorporation of aluminum ion into the lattice, Zn(AlxGa1-x)2O4. Two main broad-band emission spectra centered at around 360 and 430 nm in the range of 300-600 nm were observed in the spinel solid solutions under excitation at 270 nm, thought their broad-band emission spectra and their peak wavelengths subtly changed depending on the composition and heat treatment.

  15. Induced gyrotropy in NaBi(Mo1-xWxO4)2 solid solutions

    OpenAIRE

    L.Lutsiv-Shumski; Y.Shopa; I.Girnyk

    2000-01-01

    The dependencies of refractive indices and electrogyration parameters on tungsten concentration are obtained for the NaBi(Mo1-xWxO4)2 solid solutions with the sheelite structure. The coefficient of the transverse electrogyration effect is measured and the influence of temperature on the longitudinal electrogyration value is studied. It is shown that the refractive indices and electrogyration coefficients decrease with increasing the tungsten concentration.

  16. PAC experiments for a short range study of the Zr(10%Pr)O{sub 2} solid solution

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, J. A.; Caracoche, M. C., E-mail: cristina@fisica.unlp.edu.ar [Universidad Nacional de La Plata, Departamento de Fisica - IFLP, Facultad de Ciencias Exactas (Argentina); Rivas, P. C. [Universidad Nacional de La Plata, IFLP - Facultad de Ciencias Agronomicas y Forestales (Argentina); Rodriguez, A. M. [Universidad Nacional de La Plata, Departamento de Fisica - IFLP, Facultad de Ciencias Exactas (Argentina)

    2006-07-15

    A Zr(10 mol % Pr)O{sub 2} powder obtained by high-energy ball milling has been investigated at nanoscopic scale using primarily the Perturbed Angular Correlations technique. The aim has been to determine the nanoconfigurations around Zr{sup 4+} cations present in the solid solution and their thermal evolution with the intention of providing knowledge on the stability of the system. Results indicate that the milled product is a substitutional cubic solid solution described by two hyperfine interactions: a highly disordered interaction due to oxygen vacancies located very close to Zr{sup 4+} and an ordered interaction probably depicting a charge distribution including Pr{sup 3+} as nearest neighbor to Zr{sup 4+} probes. On cooling from high temperatures, monoclinic zirconia appears mostly at the expense of the oxygen defective cubic form. A gradual cooling indicates that destabilization of the solid solution takes place around 500{sup o}C. Thermal cycling leads to increasing amounts of the monoclinic phase.

  17. Crystal-chemistry insight into the photocatalytic activity of BiOCl x Br1- x nanoplate solid solutions

    Science.gov (United States)

    Xu, Huan-Yan; Han, Xu; Tan, Qu; Wu, Ke-Jia; Qi, Shu-Yan

    2017-06-01

    In this study, a facile alcoholysis method was developed to synthesize BiOCl x Br1- x nanoplates at room temperature and atmospheric pressure. In this route, strong acid or alkaline environment was absolutely avoided to realize the high exposure of {001} crystal facets. The regular changes in XRD peaks and cell parameters as a function of the Br content strongly declared that the obtained BiOCl x Br1- x products belonged to a group of solid solutions. The 2D nanosheets with in-plane wrinkles were clearly observed in TEM images. Interestingly, as the Br content increased, band gaps of BiOCl x Br1- x solid solutions gradually decreased. The photocatalytic degradation of RhB under simulated sunlight irradiation indicated that BiOCl0.5Br0.5 had the best photocatalytic activity. From the viewpoint of crystal chemistry, the photocatalytic activity of BiOCl x Br1- x solid solutions was closely related with the exposure amount of {001} facets, interlayer spacing of (001) plane and energy-level position of valence band.

  18. Pressure-volume equation of state for pyrope-almandine solid solutions

    Science.gov (United States)

    Nestola, Fabrizio; Milani, Sula; Angel, Ross J.; Pasqual, Daria; Geiger, Charles A.

    2013-04-01

    Garnet is a key phase of Earth's upper mantle and one of the most abundant solid inclusions in diamonds. The pyrope component (Mg3Al2Si3O12, Py) of garnet found in diamonds of peridotitic and eclogitic origin can be as high as about 79 and 43%, respectively and the almandine component (Fe3Al2Si3O12, Al) is about 11 and 33%, respectively. Thus such garnets are largely Py-Al-rich solid solutions (Stachel and Harris, 2008). To determine the depth of formation of diamond-inclusion pairs, precise and accurate thermoelastic parameters for both the diamond and the solid inclusion phase are necessary (e.g. Izraeli et al., 1999; Howell et al., 2010; Nestola et al., 2011; Howell et al., 2012). We are presently investigating the pressure-volume equation of state for a series of synthetic garnets along the binary pyrope-almandine by X-ray single-crystal diffraction using a diamond anvil cell up to a maximum of 8 GPa pressure. We have completed measurements on two crystals of composition Fe3Al2Si3O12 and Fe1.20Mg1.80Al2Si3O12. The equation of state coefficients obtained by fitting a third-order Birch-Murnaghan to the pressure-volume data show that an increase in the pyrope component in garnet causes a slight decrease of the isothermal bulk modulus, KT0, by about 3%, whereas the first pressure derivative term does not vary. Applying our results to obtain the pressure of formation of a natural diamond-garnet pair, and assuming a garnet composition close to Fe1.20Mg1.80Al2Si3O12, we obtain a pressure of encapsulation (or formation if garnet and diamond are syngenetic) of garnet in diamond between 6.5 and 7.0 GPa. References Howell, D., Wood, I.G., Dobson, D.P., Jones, A.P., Nasdala, L., Harris, J.W. (2010) Contrib. Mineral. Petrol., 160, 705-717. Howell, D., Wood, I.G., Nestola, F., Nimis, P., Nasdala, L. (2012) Eur. J. Mineral., ,. Izraeli, E.S., Harris, J.W., Navon, O. (1999) Earth Planet Sci. Lett., 173, 351-360. Nestola, F., Nimis, P., Ziberna, L., Longo, M., Marzoli, A

  19. Compensative alloying of Cr-Si low-alloyed steels

    Energy Technology Data Exchange (ETDEWEB)

    Lunika, M., E-mail: mlunika@ipflab.sumy.ua [Institute of Applied Physics, National Academy of Science of Ukraine, 58, Petropavlovskaja Str., 40030 Sumy (Ukraine)

    2010-03-25

    The principle of choosing alloy elements in order to suppress the embrittlement of solid solution strengthening is proposed. In the case of Cr-Si low-alloyed steels, the effects of compensative alloying are studied. The ultimate tensile strength and impact toughness of Cr-Si steels microalloyed with Mo, V, and Ti are determined to prove the aspects. The structure of these steels is studied using optical and transmission electron microscopy techniques after applying the optimum heat treatment. The kinetics of phase transformation after quenching and tempering have been examined by means of measurements of specific electrical resistance and magnetic parameters. It is shown that at the Si-content of about 1 wt% high values of tensile strength and impact toughness are simultaneously obtained. It is established by calculations that, for the indicated steel, long-range distortions of the crystal lattice become close to zero at the Si-content of about 1 wt%.

  20. Electronic structure and photocatalytic activities of (Bi2-δYδ)Sn2O7 solid solution

    Science.gov (United States)

    Fan, Wenjie; Hu, Jinli; Huang, Jing; Wu, Xin; Lin, Sen; Huang, Caijin; Qiu, Xiaoqing

    2015-12-01

    A series of (Bi2-δYδ)Sn2O7 solid solutions were prepared by a one-step hydrothermal method to investigate the correlation between the electronic structures and photocatalytic activity. All the (Bi2-δYδ)Sn2O7 samples were characterized by X-ray diffraction, transmission electron microscopy, infrared and UV-vis absorption spectroscopy, and the Brunauer-Emmett-Teller technique. The effects of Bi 6s orbitals in (Bi2-δYδ)Sn2O7 solid solutions on the electronic structures and photogradation of colorless 2-naphthol solution were investigated experimentally and theoretically. It is found that the introduction of Y3+ induces the shrinkage of the lattice of (Bi2-δYδ)Sn2O7 solid solutions. Consequently, the contribution of Bi 6s orbitals to electronic structures of (Bi2-δYδ)Sn2O7 solid solutions can be continuously tuned by Y3+ substitution for Bi3+. Density function theory calculations reveal that the Bi 6s and O 2p states dominate the top of valence band of Bi2Sn2O7, while the bottom of conduction band mainly consists of the states of Sn 5s, O 2p and Bi 6p. Once the Bi3+ ions are substituted by Y3+, the intensity of Bi 6s states is weakening at the top of valence band while the bottom of conduction band retains the same feature observed for pure Bi2Sn2O7. Moreover, the band dispersions of valence band and conduction band become narrower after Y3+ introduction into the lattice of (Bi2-δYδ)Sn2O7 solid solutions. As a result, the photocatalytic performance for decomposition of 2-naphthol has been suppressed by the Y3+ substitution, since the electronic structure limits the mobility of the photoinduced charge carriers. Our results suggest that high photocatalytic activity of Bi-containing compounds should originate from the good band dispersions of valence band and conduction band involving the Bi 6s orbitals.

  1. Thermodynamics of magnesian calcite solid-solutions at 25°C and 1 atm total pressure

    Science.gov (United States)

    Busenberg, Eurybiades; Plummer, L. Niel

    1989-01-01

    The stability of magnesian calcites was reexamined, and new results are presented for 28 natural inorganic, 12 biogenic, and 32 synthetic magnesian calcites. The magnesian calcite solid-solutions were separated into two groups on the basis of differences in stoichiometric solubility and other physical and chemical properties. Group I consists of solids of mainly metamorphic and hydrothermal origin, synthetic calcites prepared at high temperatures and pressures, and synthetic solids prepared at low temperature and very low calcite supersaturations () from artificial sea water or NaClMgCl2CaCl2solutions. Group I solids are essentially binary s of CaCO2 and MgCO2, and are thought to be relatively free of structural defects. Group II solid-solutions are of either biogenic origin or are synthetic magnesian calcites and protodolomites (0–20 and ∼ 45 mole percent MgCO3) prepared at high calcite supersaturations () from NaClNa2SO4MgCl2CaCl2 or NaClMgCl2CaCl2 solutions. Group II solid-solutions are treated as massively defective solids. The defects include substitution foreign ions (Na+ and SO42−) in the magnesian calcite lattice (point defects) and dislocations (~2 · 109 cm−2). Within each group, the excess free energy of mixing, GE, is described by the mixing model , where x is the mole fraction of the end-member Ca0.5Mg0.5CO3 in the solid-solution. The values of A0and A1 for Group I and II solids were evaluated at 25°C. The equilibrium constants of all the solids are closely described by the equation ln , where KC and KD are the equilibrium constants of calcite and Ca0.5Mg0.5CO3. Group I magnesian calcites were modeled as sub-regular solid-solutions between calcite and dolomite, and between calcite and “disordered dolomite”. Both models yield almost identical equilibrium constants for these magnesian calcites. The Group II magnesian calcites were modeled as sub-regular solid-solutions between defective calcite and

  2. Structural, Electronic, and Optical Properties of BiOX1−xYx (X, Y = F, Cl, Br, and I) Solid Solutions from DFT Calculations

    Science.gov (United States)

    Zhao, Zong-Yan; Liu, Qing-Lu; Dai, Wen-Wu

    2016-01-01

    Six BiOX1−xYx (X, Y = F, Cl, Br, and I) solid solutions have been systematically investigated by density functional theory calculations. BiOCl1−xBrx, BiOBr1−xIx, and BiOCl1−xIx solid solutions have very small bowing parameters; as such, some of their properties increase almost linearly with increasing x. For BiOF1−xYx solid solutions, the bowing parameters are very large and it is extremely difficult to fit the related calculated data by a single equation. Consequently, BiOX1−xYx (X, Y = Cl, Br, and I) solid solutions are highly miscible, while BiOF1−xYx (Y = Cl, Br, and I) solid solutions are partially miscible. In other words, BiOF1−xYx solid solutions have miscibility gaps or high miscibility temperature, resulting in phase separation and F/Y inhomogeneity. Comparison and analysis of the calculated results and the related physical–chemical properties with different halogen compositions indicates that the parameters of BiOX1−xYx solid solutions are determined by the differences of the physical–chemical properties of the two halogen compositions. In this way, the large deviation of some BiOX1−xYx solid solutions from Vegard’s law observed in experiments can be explained. Moreover, the composition ratio of BiOX1−xYx solid solutions can be measured or monitored using optical measurements. PMID:27549344

  3. High-strength and high-RRR Al-Ni alloy for aluminum-stabilized superconductor

    CERN Document Server

    Wada, K; Sakamoto, H; Yamamoto, A; Makida, Y

    2000-01-01

    The precipitation type aluminum alloys have excellent performance as the increasing rate in electric resistivity with additives in the precipitation state is considerably low, compared to that of the aluminum alloy with additives in the solid-solution state. It is possible to enhance the mechanical strength without remarkable degradation in residual resistivity ratio (RRR) by increasing content of selected additive elements. Nickel is the suitable additive element because it has very low solubility in aluminum and low increasing rate in electric resistivity, and furthermore, nickel and aluminum form intermetallic compounds which effectively resist the motion of dislocations. First, Al-0.1wt%Ni alloy was developed for the ATLAS thin superconducting solenoid. This alloy achieved high yield strength of 79 MPa (R.T.) and 117 MPa (4.2 K) with high RRR of 490 after cold working of 21% in area reduction. These highly balanced properties could not be achieved with previously developed solid-solution aluminum alloys. ...

  4. Enhanced photocatalytic degradation of 2-propanol over macroporous GaN/ZnO solid solution prepared by a novel sol-gel method

    Directory of Open Access Journals (Sweden)

    Lizhong Wang

    2015-10-01

    Full Text Available Macroporous GaN/ZnO solid solution photocatalyst is synthesized through a novel sol-gel method under mild conditions. The performance of as-synthesized solid solution photocatalyst is evaluated for decomposition of gaseous 2-propanol (IPA. It is found that due to enhancement in both the adsorption to gaseous IPA and the absorbance to visible light, the porous GaN/ZnO solid solution exhibits a good photocatalytic performance for IPA decomposition. Moreover, the mechanism for photocatalytic degradation IPA over porous GaN/ZnO solid solution is also investigated in comparison with those for the two end materials ZnO and GaN. The trapping effects with different scavengers prove that both the photoexcited electrons and holes affect the IPA photodegradation process, simultaneously.

  5. A model for trace metal sorption processes at the calcite surface: Adsorption of Cd2+ and subsequent solid solution formation

    Science.gov (United States)

    Davis, J.A.; Fuller, C.C.; Cook, A.D.

    1987-01-01

    The rate of Cd2+ sorption by calcite was determined as a function of pH and Mg2+ in aqueous solutions saturated with respect to calcite but undersaturated with respect to CdCO3. The sorption is characterized by two reaction steps, with the first reaching completion within 24 hours. The second step proceeded at a slow and nearly constant rate for at least 7 days. The rate of calcite recrystallization was also studied, using a Ca2+ isotopic exchange technique. Both the recrystallization rate of calcite and the rate of slow Cd2+ sorption decrease with increasing pH or with increasing Mg2+. The recrystallization rate could be predicted from the number of moles of Ca present in the hydrated surface layer. A model is presented which is consistent with the rates of Cd2+ sorption and Ca2+ isotopic exchange. In the model, the first step in Cd2+ sorption involves a fast adsorption reaction that is followed by diffusion of Cd2+ into a surface layer of hydrated CaCO3 that overlies crystalline calcite. Desorption of Cd2+ from the hydrated layer is slow. The second step is solid solution formation in new crystalline material, which grows from the disordered mixture of Cd and Ca carbonate in the hydrated surface layer. Calculated distribution coefficients for solid solutions formed at the surface are slightly greater than the ratio of equilibrium constants for dissolution of calcite and CdCO3, which is the value that would be expected for an ideal solid solution in equilibrium with the aqueous solution. ?? 1987.

  6. Mechanical alloying of an immiscible α-Fe2O3-SnO2 ceramic

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Lin, Rong; Mørup, Steen

    1997-01-01

    A solid solution of about 6 mol% SnO2 in alpha-Fe2O3 has been prepared by mechanical alloying of alpha-Fe2O3 and SnO2 powder blends. This result demonstrates that high energy ball milling can be used to prepare metastable oxide solid solutions with an extended range of compositions...... in the immiscible ceramic oxide system. X-ray diffraction and Mossbauer spectroscopy investigations show that mechanical milling of alpha-Fe2O3 and SnO2 involves alloying on an atomic scale and that true solid solution formation occurs. We suggest that the high defect concentration and the chemical enthalpy of Fe3......+-O2--Sn4+ interfaces between nanostructured alpha-Fe2O3 and SnO2 regions may serve as a driving force for the formation of a solid solution in the immiscible ceramic system....

  7. Microhardness and In Vitro Corrosion of Heat-Treated Mg–Y–Ag Biodegradable Alloy

    Science.gov (United States)

    Vlček, Marián; Lukáč, František; Kudrnová, Hana; Smola, Bohumil; Stulíková, Ivana; Luczak, Monika; Szakács, Gábor; Hort, Norbert; Willumeit-Römer, Regine

    2017-01-01

    Magnesium alloys are promising candidates for biodegradable medical implants which reduce the necessity of second surgery to remove the implants. Yttrium in solid solution is an attractive alloying element because it improves mechanical properties and exhibits suitable corrosion properties. Silver was shown to have an antibacterial effect and can also enhance the mechanical properties of magnesium alloys. Measurements of microhardness and electrical resistivity were used to study the response of Mg–4Y and Mg–4Y–1Ag alloys to isochronal or isothermal heat treatments. Hardening response and electrical resistivity annealing curves in these alloys were compared in order to investigate the effect of silver addition. Procedures for solid solution annealing and artificial aging of the Mg–4Y–1Ag alloy were developed. The corrosion rate of the as-cast and heat-treated Mg–4Y–1Ag alloy was measured by the mass loss method. It was found out that solid solution heat treatment, as well artificial aging to peak hardness, lead to substantial improvement in the corrosion properties of the Mg–4Y–1Ag alloy. PMID:28772414

  8. Fast Li ionic conduction in solid solutions of the system Li4GeO4-Li2ZnGeO4-Li3PO4

    NARCIS (Netherlands)

    Kamphorst, J.G.; Hellstrom, E.E.

    A wide range of solid solution formation in the Li4GeO4-Li2ZnGeO4-Li3PO4 system was observed to occur with a structure based on γII-Li3PO4. This includes the fast Li conductor lisicon (Li14Zn(GeO4)4). The ionic conductivities of solid solutions in this systems are reported. Much of the solid

  9. Effective scintillation materials based on solid solutions ZnS1–xTex and perspectives of their application

    Directory of Open Access Journals (Sweden)

    Katrunov K. A.

    2011-04-01

    Full Text Available The optimal technological regime of formation ZnS1–xTex solid solution at spacing 0,0≤х≤0,1 has been determined, and has been shown that fritting in hydrogen atmosphere results in more rapid reaction in comparison to argon due to chemical-thermal etching the ZnO layer out. Further annealing in the inert Ar atmosphere leads to the increase of the light output, to the intensive emission band formation and causes afterglow level reduction and the crystalline lattice rearrangement.

  10. Sonochemical synthesis of Cd{sub 1−x}Zn{sub x}S solid solutions for application in photocatalytic reforming of glycerol to produce hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Paula A.L., E-mail: paulaaparecida_lopes@hotmail.com [Instituto de Química, Universidade Federal da Bahia, Campus de Ondina, 40170-115 Salvador, BA (Brazil); Mascarenhas, Artur J.S., E-mail: artur@ufba.br [Instituto de Química, Universidade Federal da Bahia, Campus de Ondina, 40170-115 Salvador, BA (Brazil); Instituto Nacional de Ciência e Tecnologia, INCT, de Energia e Ambiente, Universidade Federal da Bahia, 40170-290 Salvador, BA (Brazil); Silva, Luciana A., E-mail: las@ufba.br [Instituto de Química, Universidade Federal da Bahia, Campus de Ondina, 40170-115 Salvador, BA (Brazil); Instituto Nacional de Ciência e Tecnologia, INCT, de Energia e Ambiente, Universidade Federal da Bahia, 40170-290 Salvador, BA (Brazil)

    2015-11-15

    A simple sonochemical method for the preparation of Cd{sub 1−x}Zn{sub x}S solid solutions was successfully applied. The sonochemical method has shown to be fast, with low energy demand and allowed to obtain nano-sized particles. The obtained materials were characterized by XRD, EDX, SEM and DRS UV/vis. The Pt-loaded photocatalysts were evaluated in photoinduced reforming of glycerol under visible light irradiation (λ > 418 nm). Pure CdS and solid solutions obtained by sonochemical method have shown photocatalytic activity with respect to hydrogen gas production. The maximum hydrogen evolution rate achieved was 239 μmol g{sup −1} h{sup −1}, when the solid solution Cd{sub 0.6}Zn{sub 0}.{sub 4}S contaminated with γ-Zn(OH){sub 2} was irradiated with visible light. - Highlights: • Cd{sub 1−x}Zn{sub x}S solid solutions were successfully prepared by a sonochemical method. • The solid solutions are active in photocatalytic reforming of glycerol. • The solid solution Cd{sub 0.6}Zn{sub 0.4}S contaminated with γ-Zn(OH){sub 2} was the more active photocatalyst.

  11. Electrical conductivity in single crystals of GaSe x Te1 - x solid solutions in strong electrical fields

    Science.gov (United States)

    Tagiev, B. G.; Tagiev, O. B.

    2017-06-01

    This paper presents some results of studying the Poole-Frenkel effect with allowance for shielding in layered GaSe and GaTe single crystals and their solid solutions in strong electrical fields of up to 105 V/cm at temperatures of 103-250 K. According to the relationship (σ/σ(0))^{1/2} logσ/σ(0) = E√{ɛ/4π n(0)kT}, there exists a linear dependence between (σ/σ(0))^{1/2} logσ/σ(0) and the electrical field E (σ is the electrical conductivity in strong electrical fields, and σ(0) is the electrical conductivity in the ohmic region). The slopes of these lines have been determined at different temperatures (103-250 K) by estimating the concentration of current carriers n(0) = 3 × 1013-5 × 1015 cm-3 in the ohmic region of the electrical conductivity of solid solutions of layered GaSe x Te1- x single crystals ( x = 1.00, 0.95, 0.90, 0.80, 0.70, 0.30, 0.20, 0.10, 0).

  12. Nonlinear photoluminescence of graded band-gap Al sub x Ga sub 1 sub - sub x As solid solutions

    CERN Document Server

    Kovalenko, V F; Shutov, S V

    2002-01-01

    The dependence of the photoluminescence (PL) intensity of undoped and doped graded band-gap Al sub x Ga sub 1 sub - sub x As (x <= 0.36) solid solutions on the excitation level J (1 x 10 sup 1 sup 9 <= J <= 1 x 10 sup 2 sup 2 quantum cm sup - sup 2 s) for different values of built-in quasi-electrical field E (85 <= E <= 700 V/cm) has been studied. It is found that the dependence of the near-band-edge PL intensity I in the excitation level J at an accelerating action of the field E has a complex character. The nonlinearity of I(J) dependence is explained by contribution of the two-photon absorption of the radiating recombination in the process of its remission. The optimum range of E values (120 <= E <= 200 V/cm) providing the greatest contribution of the two-photon absorption in the reemission in undoped solid solutions is determined

  13. Accurate solid solution range of BiMnxFe3-xO6 and low temperature magnetism

    Science.gov (United States)

    Jiang, Pengfei; Yue, Mufei; Cong, Rihong; Gao, Wenliang; Yang, Tao

    2017-11-01

    BiMnxFe3-xO6 (x = 1) represents a new type of oxide structure containing Bi3+ and competing magnetic super-exchanges. In literature, multiple magnetic states were realized at low temperatures in BiMnFe2O6, and the hypothetical parent compounds (BiMn3O6, BiFe3O6) were predicted to be different in magnetism. Herein, we performed a careful study on the syntheses of BiMnxFe3-xO6 at ambient pressure, and the solid solution range was determined to be 0.9 ≤ x ≤ 1.3 by Rietveld refinements on high-quality powder X-ray diffraction data. Due to the very similar cationic size of Mn3+ and Fe3+, and possibly the structural rigidity, there was no significant structure change in the whole range of solid solution. The magnetic behavior of BiMnxFe3-xO6 (x = 1.2, 1.22, 1.26, 1.28 and 1.3) was generally similar to BiMnFe2O6, while the relative higher concentration of Mn3+ led to the decreasing of the antiferromagnetic ordering temperature.

  14. Atomistic simulations of nanocrystalline U0.5Th0.5O2 solid solution under uniaxial tension

    Directory of Open Access Journals (Sweden)

    Hongxing Xiao

    2017-12-01

    Full Text Available Molecular dynamics simulations were performed to investigate the uniaxial tensile properties of nanocrystalline U0.5Th0.5O2 solid solution with the Born–Mayer–Huggins potential. The results indicated that the elastic modulus increased linearly with the density relative to a single crystal, but decreased with increasing temperature. The simulated nanocrystalline U0.5Th0.5O2 exhibited a breakdown in the Hall–Petch relation with mean grain size varying from 3.0 nm to 18.0 nm. Moreover, the elastic modulus of U1-yThyO2 solid solutions with different content of thorium at 300 K was also studied and the results accorded well with the experimental data available in the literature. In addition, the fracture mode of nanocrystalline U0.5Th0.5O2 was inclined to be ductile because the fracture behavior was preceded by some moderate amount of plastic deformation, which is different from what has been seen earlier in simulations of pure UO2.

  15. Thermodynamics of aragonite-strontianite solid solutions: Results from stoichiometric solubility at 25 and 76°C

    Science.gov (United States)

    Plummer, L.N.; Busenberg, E.

    1987-01-01

    Dissolution of synthetic strontianite-aragonite solid solutions was followed analytically to stoichiometric saturation using large solid to solution ratios in CO2-H2O solution at 25 and 76°C. The compositional dependence of the equilibrium constant was calculated from the composition of saturated (stoichiometric) solutions and used to calculate the activities and activity coefficients of CaCO3 and SrCO3 in the solid Ca(1−x)SrxCO3 at 25 and 76°C. The results show that the solid-solution is not regular but unsymmetrical. The excess free energy of mixing is closely modeled for all compositions by the relation where A0 is 8.49 ± 0.30 and 7.71 ± 0.20 KJ/mole and A1 is −4.51 ± 0.20 and −3.36 ± 0.40 KJ/mole at 25 and 76°C, respectively. The equilibrium constant is denned as a function of the SrCO3 mole fraction, x, by the relation where R is the gas constant, T is in Kelvins and KA and KS are the aragonite and strontianite equilibrium constants.

  16. Evidence of alloy formation during the activation of graphite-supported palladium-cobalt catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Noronha, F.B.; Schmal, M. [Univ. Federal do Rio de Janeiro (Brazil); Frety, R. [CNRS, Villeurbanne (France). Lab. d`Application de la Chimie a l`Environnement; Bergeret, G.; Moraweck, B. [CNRS, Villeurbanne (France). Inst. de Recherches sur la Catalyse

    1999-08-15

    Magnetism, XRD, and EXAFS analyses were used to study the formation of a solid solution on Pd-Co/G catalysts during reduction treatment. After reduction at 773 K, magnetic measurements revealed the formation of a Pd-Co alloy. XRD analysis in situ allowed one to follow the alloy process during the increase of the reduction temperature. The XRD results showed the presence of a heterogeneous solid solution after reduction at 773 K. Pd and Co K-edge EXAFS analysis confirmed that bimetallic particles with a palladium- and cobalt-rich phase were formed. The formation of a solid solution decreased the adsorption strength of 1,3-butadiene on new Pd sites modified by Co. Palladium-cobalt catalysts are useful for methanol and ethanol formation from synthesis gas at high pressure.

  17. Preliminary design studies of a 100 MeV H-/H+LINAC as injector for ...

    Indian Academy of Sciences (India)

    Preliminary design studies of a 100 MeV H-/H+LINAC as injector for SNS synchrotron/ADS LINAC. S A PANDE, MOONOOKU PRASAD, NITA KULKARNI and P R HANNURKAR. Centre for Advanced Technology, Indore 452 013, India. Abstract. It is proposed to construct a spallation neutron source (SNS) at Centre for ...

  18. Structure induced Yb valence changes in the solid solution Yb(x)Ca(1-x)C2.

    Science.gov (United States)

    Link, Pascal; Glatzel, Pieter; Kvashnina, Kristina; Trots, Dmytro M; Smith, Ronald I; Ruschewitz, Uwe

    2013-06-17

    The solid solution Yb(x)Ca(1-x)C2 (0 ≤ x ≤ 1) was synthesized by reaction of the elements at 1323 K. The crystal structures within this solid solution, as elucidated from synchrotron powder diffraction data, depend on x and exhibit some interesting features that point to a structure dependent valence state of Yb. Compounds with x ≥ 0.75 crystallize in the tetragonal CaC2 type structure (I4/mmm, Z = 2) and obey Vegard's law; for x ≤ 0.75 the monoclinic ThC2 type structure (C2/c, Z = 4) is found, which coexists with the monoclinic CaC2-III type structure (C2/m, Z = 4) for x ≤ 0.25. The monoclinic modifications show a strong deviation from Vegard's law. Their unit cell volumes are remarkably larger than expected for a typical Vegard system. HERFD-XANES spectroscopic investigations reveal that different Yb valence states are responsible for the observed volume anomalies. While all tetragonal compounds contain mixed-valent Yb with ∼75% Yb(3+) (similar to pure YbC2), all monoclinic modifications contain exclusively Yb(2+). Therefore, Yb(x)Ca(1-x)C2 is a very rare example of a Yb containing compound showing a strong structure dependence of the Yb valence state. Moreover, temperature dependent synchrotron powder diffraction, neutron TOF powder diffraction, and HERFD-XANES spectroscopy experiments reveal significant Yb valence changes in some compounds of the Yb(x)Ca(1-x)C2 series that are induced by temperature dependent phase transitions. Transitions from the tetragonal CaC2 type structure to the monoclinic ThC2 or the cubic CaC2-IV type structure (Fm3m, Z = 4) are accompanied by drastic changes of the mean Yb valence from ∼2.70 to 2.0 in compounds with x = 0.75 and x = 0.91. Finally, the determination of lattice strain arising inside the modifications with ordered dumbbells (ThC2 and CaC2 type structures) by DSC measurements corroborated our results concerning the close relationship between crystal structure and Yb valence in the solid solution Yb(x)Ca(1-x

  19. Defect microstructure in copper alloys irradiated with 750 MeV protons

    DEFF Research Database (Denmark)

    Zinkle, S.J.; Horsewell, A.; Singh, B.N.

    1994-01-01

    Transmission electron microscopy (TEM) disks of pure copper and solid solution copper alloys containing 5 at% of Al, Mn, or Ni were irradiated with 750 MeV protons to damage levels between 0.4 and 2 displacements per atom (dpa) at irradiation temperatures between 60 and 200 degrees C. The defect...

  20. Sc-45 nuclear magnetic resonance analysis of precipitation in dilute Al-Sc alloys

    NARCIS (Netherlands)

    Celotto, S; Bastow, TJ

    Nuclear magnetic resonance (NMR) with Sc-45 is used to determine the solid solubility of scandium in aluminium and to follow the precipitation of Al3Sc during the ageing of an Al-0.06 at.% Sc alloy via the two fully resolved peaks, corresponding to Sc in the solid solution Al matrix and to Sc in the

  1. Long-ranged interactions in bcc NbMoTaW high-entropy alloys

    NARCIS (Netherlands)

    Kormann, F.H.W.; Ruban, A.V.; Sluiter, M.H.F.

    2017-01-01

    We reveal that in a prototypical bcc high-entropy alloy NbMoTaW chemical interactions are long ranged and highly frustrated. We show that this is the reason that bcc solid solutions in NbMoTaW can persist to low temperatures. The ab initio-computed long-ranged interactions strongly impact

  2. Hopping conduction via highly localized impurity states of indium in PbTe and its solid solutions. Review

    CERN Document Server

    Ravich, Y I

    2002-01-01

    Results of experimental investigation of the transport phenomena in PbTe and Pb sub 1 sub - sub x Sn sub x Te solid solutions with high contents of In impurity (up to 20 at %) at temperatures up to 400 K have been considered. An analysis of the experimental data has been made on the base of an idea of hopping conductivity via highly localized impurity states creates by indium atoms. The temperature dependences of transport coefficients unusual for the IV-VI-type semiconductors, the change of sing of the thermoelectromotive force at negative Hall coefficient, the positive Nernst-Ettingshausen coefficient are explained. The activation energy of the hoping conductivity, characterizing discrepancy between impurity energy levels the effective wave function radius and the density of localized states as the energy function are found experimentally

  3. Simulation of ceramic materials relevant for nuclear waste management: Case of La1-xEuxPO4 solid solution

    Science.gov (United States)

    Kowalski, Piotr M.; Ji, Yaqi; Li, Yan; Arinicheva, Yulia; Beridze, George; Neumeier, Stefan; Bukaemskiy, Andrey; Bosbach, Dirk

    2017-02-01

    Using powerful computational resources and state-of-the-art methods of computational chemistry we contribute to the research on novel nuclear waste forms by providing atomic scale description of processes that govern the structural incorporation and the interactions of radionuclides in host materials. Here we present various results of combined computational and experimental studies on La1-xEuxPO4 monazite-type solid solution. We discuss the performance of DFT + U method with the Hubbard U parameter value derived ab initio, and the derivation of various structural, thermodynamic and radiation-damage related properties. We show a correlation between the cation displacement probabilities and the solubility data, indicating that the binding of cations is the driving factor behind both processes. The combined atomistic modeling and experimental studies result in a superior characterization of the investigated material.

  4. Infrared Optical Properties of β-Spodumene Solid Solution Glass-Ceramic for Fiber-Optic Devices

    Science.gov (United States)

    Sakamoto, Akihiko; Yamamoto, Shigeru

    2006-09-01

    The IR optical properties of an opaque β-spodumene solid solution (s.s.) glass-ceramic for fiber-optic devices were studied in relation to its refractive indices in both crystalline and glass phases. We investigated the refractive indices of both phases on the basis of IR transmittance change due to the structural relaxation of the glass phase. The refractive indices of this β-spodumene s.s. glass-ceramic at a wavelength of 1550 nm in the crystalline and glass phases were first determined to be 1.530 and 1.495, respectively. It was found from the refractive index data that the optical scattering intensity of this glass-ceramic approximately follows the Rayleigh-Gans model. We also demonstrated that the inner diameter of an opaque glass-ceramic capillary used in optical fiber connectors can be optically measured with a sub-micrometer accuracy using an IR laser.

  5. Structural and Microstructural Correlations of Physical Properties in Natural Almandine-Pyrope Solid Solution: Al70Py29

    Science.gov (United States)

    Sibi, N.; Subodh, G.

    2017-09-01

    Garnets are naturally occurring minerals with the general formula X3Y2Z3O12 having various applications. In the present study, the structural and physical properties of a garnet mineral obtained from Indian Rare Earth Ltd., Manavalakurichi, Tamil Nadu, India were comprehensively investigated. The compositional analysis using electron probe micro analysis (EPMA) revealed that the mineral belongs to almandine-pyrope solid solution (Al70Py29) with the chemical formula (Fe1.72Mg0.8Mn0.01Ca0.02) (Fe0.04Al2.36) Si2.93O12. Rietveld refinement of the x-ray diffraction pattern confirms that the space group is Ia{ - }\\overline{3} d with refined cubic lattice parameter a = 11.550(4) Å. The refined occupancy values of multiple cations in the dodecahedral and octahedral sites are in agreement with the EPMA data. Fourier transform infrared and FT Raman spectra show bands corresponding to almandine-pyrope solid solution. Peak splitting of IR and Raman bands confirms presence of multiple cations in the dodecahedral site. Thermogravimetric/differential thermal analysis shows that the mineral is stable up to 600°C in spite of the presence of Fe2+ ions. Low temperature magnetic susceptibility data is in agreement with the amount of Fe2+ ions present in the mineral. The dielectric constant of the mineral varied from 6 to 16.5 when sintered at temperatures ranging from 600°C to 1250°C.

  6. Evolution of magnetic properties in the normal spinel solid solution Mg(1-x)Cu(x)Cr2O4.

    Science.gov (United States)

    Kemei, Moureen C; Moffitt, Stephanie L; Shoemaker, Daniel P; Seshadri, Ram

    2012-02-01

    We examine the evolution of magnetic properties in the normal spinel oxides Mg(1-x)Cu(x)Cr2O4 using magnetization and heat capacity measurements. The end-member compounds of the solid solution series have been studied in some detail because of their very interesting magnetic behavior. MgCr2O4 is a highly frustrated system that undergoes a first-order structural transition at its antiferromagnetic ordering temperature. CuCr2O4 is tetragonal at room temperature as a result of Jahn-Teller active tetrahedral Cu2+ and undergoes a magnetic transition at 135 K. Substitution of magnetic cations for diamagnetic Mg2+ on the tetrahedral A site in the compositional series Mg(1-x)Cu(x)Cr2O4 dramatically affects magnetic behavior. In the composition range 0 ≤ x ≤ ≈0.3, the compounds are antiferromagnetic. A sharp peak observed at 12.5 K in the heat capacity of MgCr2O4 corresponding to a magnetically driven first-order structural transition is suppressed even for small x. Uncompensated magnetism--with open magnetization loops--develops for samples in the x range ≈0.43 ≤ x ≤ 1. Multiple magnetic ordering temperatures and large coercive fields emerge in the intermediate composition range 0.43 ≤ x ≤ 0.47. The Néel temperature increases with increasing x across the series while the value of the Curie-Weiss Θ(CW) decreases. A magnetic temperature-composition phase diagram of the solid solution series is presented.

  7. Evolution of magnetic properties in the normal spinel solid solution Mg1-xCuxCr2O4

    Science.gov (United States)

    Kemei, Moureen C.; Moffitt, Stephanie L.; Shoemaker, Daniel P.; Seshadri, Ram

    2012-02-01

    We examine the evolution of magnetic properties in the normal spinel oxides Mg1-xCuxCr2O4 using magnetization and heat capacity measurements. The end-member compounds of the solid solution series have been studied in some detail because of their very interesting magnetic behavior. MgCr2O4 is a highly frustrated system that undergoes a first-order structural transition at its antiferromagnetic ordering temperature. CuCr2O4 is tetragonal at room temperature as a result of Jahn-Teller active tetrahedral Cu2+ and undergoes a magnetic transition at 135 K. Substitution of magnetic cations for diamagnetic Mg2+ on the tetrahedral A site in the compositional series Mg1-xCuxCr2O4 dramatically affects magnetic behavior. In the composition range 0 ≤ x ≤≈ 0.3, the compounds are antiferromagnetic. A sharp peak observed at 12.5 K in the heat capacity of MgCr2O4 corresponding to a magnetically driven first-order structural transition is suppressed even for small x. Uncompensated magnetism—with open magnetization loops—develops for samples in the x range ≈0.43 ≤ x ≤ 1. Multiple magnetic ordering temperatures and large coercive fields emerge in the intermediate composition range 0.43 ≤ x ≤ 0.47. The Néel temperature increases with increasing x across the series while the value of the Curie-Weiss ΘCW decreases. A magnetic temperature-composition phase diagram of the solid solution series is presented.

  8. Ligand effects on ESR and optical properties of gold atoms in gamma irradiated organic solid solutions at 77 K.

    Science.gov (United States)

    Hase, Yoko Miyatake; Ito, Yoshitaka; Tajima, Yusuke

    2005-10-13

    Ligand effects on ESR and optical properties of Au0 atoms produced at 77 K in gamma irradiated solid solutions of AuCl/MTHF and AuCl/EtOH with and without HCl were investigated. Four groups of ESR lines were observed at 73 K more clearly around the magnetic fields at about 250, 280, 340, and 400 mT for both gamma irradiated MTHF and EtOH solid solutions with HCl than those without HCl. The values of a and g(J) calculated by Breit-Rabi analysis showed a remarkable dependence on the solvent polarity. It was confirmed that the signals were the hyperfine quartet corresponding to the transitions between the Zeeman levels of Au0 atoms with nuclear spin of 3/2 in the ground state, 2S(1/2). It was also confirmed that Au0 atoms produced after gamma irradiation were located in the nuclear environment of isotropic interaction with surrounding ligand molecules. Delocalization of the unpaired spin density of Au0 onto ligands is found to be as large as one in the case of Cu0 atoms. Our previous hypothesis of the occurrence of configuration mixing of d valence orbital into the wave function of the atom in its 2S(1/2) was strongly supported. The dependence of the ESR, optical absorption, and the steady-state emission and excitation characteristics on solvent polarity was cleared in this study. We observed two kinds of emissions i.e., a band at 385 nm and a set of emission bands at 456, 482, 484, and 520 nm. These correspond to two bands out of the six kinds of emissions observed previously. The bands were attributed to exciplex (Au0 x Ln...Au+)* and the excited Au0 atoms trapped in a large cavity, respectively. The negative counterion of Au+ of the gold compound plays an important role for the formation of the exciplexes.

  9. Structural and magnetic characterization of the complete delafossite solid solution (CuAlO₂)₁-x(CuCrO₂)x.

    Science.gov (United States)

    Barton, Phillip T; Seshadri, Ram; Knöller, Andrea; Rosseinsky, Matthew J

    2012-01-11

    We have prepared the complete delafossite solid solution series between diamagnetic CuAlO(2) and the t(2g)(3)frustrated antiferromagnet CuCrO(2). The evolution with composition x in CuAl(1-x)Cr(x)O(2) of the crystal structure and magnetic properties has been studied and is reported here. The room-temperature unit cell parameters follow the Végard law and increase with x as expected. The μ(eff) is equal to the Cr(3+) spin-only S = 3/2 value throughout the entire solid solution. Θ(CW) is negative, indicating that the dominant interactions are antiferromagnetic, and its magnitude increases with Cr substitution. For dilute Cr compositions, the nearest-neighbor exchange coupling constant J(BB) was estimated by mean-field theory to be 3.0 meV. Despite the sizable Θ(CW), long-range antiferromagnetic order does not develop until x is almost 1, and is preceded by glassy behavior. The data presented here, and those on dilute Al substitution from Okuda et al, suggest that the reduction in magnetic frustration due to the presence of non-magnetic Al does not have as dominant an effect on magnetism as chemical disorder and dilution of the magnetic exchange. For all samples, the 5 K isothermal magnetization does not saturate in fields up to 5 T and minimal hysteresis is observed. The presence of antiferromagnetic interactions is clearly evident in the sub-Brillouin behavior with a reduced magnetization per Cr atom. An inspection of the scaled Curie plot reveals that significant short-range antiferromagnetic interactions occur in CuCrO(2) above its Néel temperature, consistent with its magnetic frustration. Uncompensated short-range behavior is present in the Al-substituted samples and is likely a result of chemical disorder.

  10. Analysis of the flow property of aluminum alloy AA6016 based on the fracture morphology using the hydroforming technology

    OpenAIRE

    Lihui Lang; Quanda Zhang; Zhiying Sun; Yao Wang

    2017-01-01

    In this paper, the hydraulic bulging experiments were respectively carried out using AA6016-T4 aluminum alloy and AA6016-O aluminum alloy, and the deformation properties and fracture mechanism of aluminum alloy under the conditions of thermal and hydraulic were analyzed. Firstly, the aluminum alloy AA6016 was dealt with two kinds of heat treatment systems such as solid solution heat treatment adding natural ageing and full annealing, then the aluminum alloy such as AA6016-T4 and AA6016-O were...

  11. Fine structures in Fe3Al alloy layer of a new hot dip aluminized steel

    Indian Academy of Sciences (India)

    The fine structure in the Fe–Al alloy layer of a new hot dip aluminized steel (HDA) was examined by means of X-ray diffractometry (XRD), electron diffraction technique, etc. The test results indicated that the Fe–Al alloy layer of the new aluminized steel mainly composed of Fe3Al, FeAl and -Fe (Al) solid solution. There was ...

  12. The effect of alloying on the ordering processes in near-alpha titanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Popov, Artemiy, E-mail: p.artemii@mail.ru [Ural Federal University named after the first President of Russia B.N. Yeltsin, 19 Mira Street, Ekaterinburg 620002 (Russian Federation); Rossina, Natalya [Ural Federal University named after the first President of Russia B.N. Yeltsin, 19 Mira Street, Ekaterinburg 620002 (Russian Federation); Popova, Maria, E-mail: pmaria777@mail.ru [Ural Federal University named after the first President of Russia B.N. Yeltsin, 19 Mira Street, Ekaterinburg 620002 (Russian Federation)

    2013-03-01

    The substructure of near-alpha Ti–Al–Sn–Zr–Mo–Si alloys containing up to 12.5 at% aluminum was studied by transmission electron microscopy (TEM). It was shown that long-range order sections are formed at aging temperatures up to 500 °C in alloys, high in aluminum, and the ordered phase is formed by the nucleation and growth mechanism at 700 °C aging temperatures. Causes of changing the phase transformation mechanism have been discussed, and the relationship between the structure and properties of alloys, depending on modes of heat treatment has been analyzed. Also the influence of aluminides and silicides precipitation on the mechanical alloy properties after aging was examined. It was shown that the aluminide formation led to a slight hardening and a significant viscosity decrease. The silicide particles formation reduced the heat resistance properties, due to the depletion of the solid solution by silicon.

  13. Bi(1-x)Ni(x)VO(4-y) Solid Solution with a High Visible-Light Photocatalytic Activity for Degradation Methyl Orange.

    Science.gov (United States)

    Wang Jing; Wei, Yuelin; Huang, Yunfang; Wu, Jihuai; Dong, Qiang; Yin, Shu; Sato, Tsugio

    2015-09-01

    Particulate solid solutions Bi(1-x)Ni(x)VO(4-y) were synthesized by solid-state reaction at high temperature. The samples were characterized by X-ray Diffraction (XRD), Field-Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectrometer (EDS), Brunauer-Emmett-Teller (BET) surface area and Ultraviolet-Visible spectroscopy (UV-Vis). The photocatalytic activity of BiVO4 for photocatalytic degradation of organic contaminants ability in visible light region could be improved by doping of Ni(2+). The high visible light photocatalytic activity of Bi(1-x)Ni(x)VO(4-y) solid solution might be due to the generation of a new band gap and expanding the range of visible light response. It was suggested that the Ni(2+) doping was beneficial to effective charge separation of Bi(1-x)Ni(x)VO(4-y) solid solution, thus improved the photocatalytic activity.

  14. Structural and Optical Investigations of Heterostructures Based on AlxGa1-xAsyP1-y:Si Solid Solutions Obtained by MOCVD

    Directory of Open Access Journals (Sweden)

    P. V. Seredin

    2014-01-01

    Full Text Available We investigated MOCVD epitaxial heterostructures based on AlxGa1−xAs ternary solid solutions, obtained in the range of compositions x~0.20–0.50 and doped with high concentrations of phosphorus and silicon atoms. Using the methods of high-resolution X-ray diffraction, scanning electron microscopy, X-ray microanalysis, Raman spectroscopy, and photoluminescence spectroscopy we have shown that grown epitaxial films represent five-component (AlxGa1−xAs1−yPy1−zSiz solid solutions. The implementation of silicon in solid solution with a concentration of ~ 0.01 at.% leads to the formation of the structure with deep levels, DX centers, the occurrence of which fundamentally affects the energy characteristics of received materials.

  15. Microstructures and Mechanical Properties of Binary Al-Zn Alloys Fabricated by Casting and Heat Treatment

    Science.gov (United States)

    Zhou, W. B.; Teng, G. B.; Liu, C. Y.; Qi, H. Q.; Huang, H. F.; Chen, Y.; Jiang, H. J.

    2017-08-01

    Binary Al-Zn alloys with different Zn contents were fabricated by casting and heat treatment. Analysis of mechanical properties showed that the hardness and tensile strength of Al-Zn alloys increased with increased Zn content, with the post-heat treatment hardness and ultimate tensile strength of Al-49Zn alloy reaching as high as 152 HV and 330 MPa, respectively. Meanwhile, the plasticity and toughness of Al-Zn alloys decreased with increased Zn content. Solid-solution strengthening was the main strengthening mechanism for Al-Zn alloys, and Orowan strengthening was also observed in Al-49Zn alloy. The fracture mode of Al-20Zn and Al-35Zn alloys was ductile, whereas Al-20Zn alloy showed good impact toughness. This work provided a basis for further improving the cast component design of the Al-Zn-X system.

  16. Microstructure and properties of novel quinary multi-principal element alloys with refractory elements

    Directory of Open Access Journals (Sweden)

    Na-na Guo

    2015-09-01

    Full Text Available Five equiatomic alloys (TiZrHfVNb, TiZrHfVTa, TiZrNbMoV, TiZrHfMoV and ZrNbMoHfV composed of five elements with high melting temperature, respectively were prepared by arc-melting to develop a novel high temperature alloy. The five alloys exhibit different dendritic and interdendritic morphologies. The TiZrHfVNb, TiZrHfVTa and TiZrNbMoV alloys formed disordered solid solution phases with body-centered cubic structure, and exhibited high compressive strength and good plasticity. The TiZrHfMoV and ZrNbMoHfV alloys are composed with Laves phase (HfMo2 and disordered solid solution phases with body-centered cubic structure. The TiZrHfMoV and ZrNbMoHfV alloys are harder and more brittle than the other three alloys due to the existence of hard and brittle Laves phases. At high temperatures, the strength decreases to below 300 MPa for the TiZrHfVNb and TiZrHfMoV alloys. Solution strengthening is the primary strengthening mechanism of the TiZrHfVNb, TiZrHfVTa and TiZrNbMoV alloys, and brittle Laves phase is the main cause for the low ductility of the TiZrHfMoV and ZrNbMoHfV alloys.

  17. (Mg,Co)O Solid-Solution Precursors for the Large-Scale Synthesis of Carbon Nanotubes by Catalytic Chemical Vapor Deposition

    OpenAIRE

    Bacsa, Revathi; Laurent, Christophe; Peigney, Alain; Vaugien, Thibaud; Flahaut, Emmanuel; Bacsa, Wolfgang; Rousset, Abel

    2002-01-01

    Single- and double-walled carbon nanotubes were produced in high yield using the selective reduction of solid solutions of Mg1–xCoxO in a methane and hydrogen atmosphere at 1000°C. The solid solutions were prepared using combustion synthesis with urea as the fuel. The BET surface areas ranged from 10 to 65 m2/g depending on the fuel content. A single crystalline phase was obtained only for fuel-rich compositions. Increased fuel content increased the surface area by a factor of 6. However, ver...

  18. Partitioning of platinum-group elements (PGE) and chalcogens (Se, Te, As, Sb, Bi) between monosulfide-solid solution (MSS), intermediate solid solution (ISS) and sulfide liquid at controlled fO2-fS2 conditions

    Science.gov (United States)

    Liu, Yanan; Brenan, James

    2015-06-01

    In order to better understand the behavior of highly siderophile elements (HSEs: Os, Ir, Ru, Rh, Pt, Pd, Au, Re), Ag, Pb and chalcogens (As, Se, Sb, Te and Bi) during the solidification of sulfide magmas, we have conducted a series of experiments to measure partition coefficients (D values) between monosulfide solid solution (MSS) and sulfide melt, as well as MSS and intermediate solid solution (ISS), at 0.1 MPa and 860-926 °C, log fS2 -3.0 to -2.2 (similar to the Pt-PtS buffer), with fO2 controlled at the fayalite-magnetite-quartz (FMQ) buffer. The IPGEs (Os, Ir, Ru), Rh and Re are found to be compatible in MSS relative to sulfide melt with D values ranging from ∼20 to ∼5, and DRe/DOs of ∼0.5. Pd, Pt, Au, Ag, Pb, as well as the chalcogens, are incompatible in MSS, with D values ranging from ∼0.1 to ∼1 × 10-3. For the same metal/sulfur ratio, D values for the IPGEs, Rh and Re are systematically larger than most past studies, correlating with higher oxygen content in the sulfide liquid, reflecting the significant effect of oxygen on increasing the activity coefficients for these elements in the melt phase. MSS/ISS partitioning experiments reveal that Ru, Os, Ir, Rh and Re are partitioned into MSS by a factor of >50, whereas Pd, Pt, Ag, Au and the chalcogens partition from weakly (Se, As) to strongly (Ag, Au) into ISS. Uniformly low MSS- and ISS- melt partition coefficients for the chalcogens, Pt, Pd, Ag and Au will lead to enrichment in the residual sulfide liquid, but D values are generally too large to reach early saturation in Pt-Pd-chalcogen-rich accessory minerals, based on current solubility estimates. Instead, these phases likely precipitate at the last dregs of crystallization. Modeled evolution curves for the PGEs and chalcogens are in reasonably good agreement with whole-rock sulfide compositions for the McCreedy East deposit (Sudbury, Ontario), consistent with an origin by crystallization of MSS, then MSS + ISS from sulfide magma.

  19. Mechanical and tribological properties of newly developed Tribaloy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Xu, W. [Department of Mechanical and Aerospace Engineering, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, K1S 5B6 (Canada); Liu, R. [Department of Mechanical and Aerospace Engineering, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, K1S 5B6 (Canada)], E-Mail: rliu@mae.carleton.ca; Patnaik, P.C. [Institute for Aerospace Research, National Research Council of Canada, 1200 Montreal Road, Ottawa, Ontario, K1A 0R6 (Canada); Yao, M.X. [Deloro Stellite Inc., P.O. Box 5300, Belleville, Ontario, K8N 5C4 (Canada); Wu, X.J. [Institute for Aerospace Research, National Research Council of Canada, 1200 Montreal Road, Ottawa, Ontario, K1A 0R6 (Canada)

    2007-04-15

    Outstanding combination of mechanical, wear and corrosion performance has been achieved in Laves intermetallic materials, termed Tribaloy alloys. In these two-phase alloys the solid solution provides high mechanical strength and fracture toughness while the Laves intermetallic phase offers excellent wear resistance. However, conventional Tribaloy alloys usually have low tensile strength and fracture toughness compared with ductile materials due to the large volume fraction of Laves phase, which has limited their application in many cases. The present research is aimed at developing advanced Tribaloy alloys with increasing ductility. Two new cobalt base alloys were developed in this research. The specimens were fabricated with a centrifugal casting technique. The material characterization was performed using the differential scanning calorimetry (DSC), scanning electron microscope (SEM), indentation and ball-on-disc tribological techniques.

  20. Microstructure and corrosion characteristics of laser-alloyed magnesium alloy AZ91D with Al–Si powder

    Directory of Open Access Journals (Sweden)

    Ming Qian, Da Li and Chang Jin

    2008-01-01

    Full Text Available Blown-powder laser surface alloying was performed on the magnesium alloy AZ91D with Al–Si alloy powder to improve corrosion resistance. Characterization by scanning electron microscopy (SEM, energy dispersive spectroscopy (EDS and x-ray diffraction (XRD analysis revealed that intermetallic compounds (IMCs of Mg2Si, Al12Mg17 and Al3Mg2 were formed in the matrix of α-Mg and Al solid solutions in Al–Si alloyed layers. The anodic polarization test in 3.5% NaCl aqueous solution showed that preferential corrosion occurred in the α-Mg matrix of the AZ91D base metal. The Al–Si alloyed layers exhibited a lower corrosion rate and a higher polarization resistance than AZ91D. The compactly dispersed dendritic Mg2Si phase, and the dendritic and angular phases of Al12Mg17 and Al3Mg2 in the alloyed microstructure were observed to be corrosion-resistant, constituting a barrier that retards corrosion. Corrosion initiated at the interface between IMCs and the solid solution matrix, and at substructures of the matrix, subsequently pervaded into the surrounding microstructure.

  1. Synthesis of (Cr,V){sub 2}(C,N) solid solution powders by thermal processing precursors

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Anrui [School of Materials Science & Engineering, Sichuan University, Chengdu, 610065 (China); Liu, Ying [School of Materials Science & Engineering, Sichuan University, Chengdu, 610065 (China); Key Laboratory of Advanced Special Material & Technology, Ministry of Education, Chengdu, 610065 (China); Ma, Shiqing; Qiu, Yuchong; Rong, Pengcheng; Ye, Jinwen [School of Materials Science & Engineering, Sichuan University, Chengdu, 610065 (China)

    2017-06-01

    The single-phase (Cr,V){sub 2}(C,N) solid solution powders were fabricated via carbothermal reduction-nitridation (CRN) processing technique. The effects of heat treatment temperature, nitrogen pressure and carbon proportion were experimentally studied in detail by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and thermal analysis. The chemical transformations of vanadium and chromium compounds were as follows: precursors → V{sub 2}O{sub 3}, Cr{sub 2}O{sub 3} → Cr{sub 3}C{sub 2}, Cr{sub 2}O{sub 3}, (Cr,V){sub 2}(C,N) → (Cr,V){sub 2}(C,N). When the heat-treated temperature was below 1200 °C, chromium oxides didn’t completely react. However, higher temperature ∼1300 °C could not only lead to the segregation of some nitrides and carbon black, but also to the occurrence of fiber-bridged particles. The system nitrogen pressure over 0.03 MPa would cause a subtle transformation of (Cr,V){sub 2}(C,N) to VCrN{sub 2}. When the carbon proportion was below 15 wt%, the oxides could not be completely reduced, while when the carbon proportion was above 15.5 wt%, some undesired carbides, like Cr{sub 23}C{sub 6} and Cr{sub 3}C{sub 2}, would form. Ultimately, the homogeneously distributed pure-phase (Cr,V){sub 2}(C,N) spherical particles with the average size of ∼1.5 μm were obtained at the optimal conditions of the treatment of precursors at 1200 °C for 1 h with the nitrogen pressure of 0.03 MPa and carbon content of 15.5 wt%. The chemical composition of the solid solution with the optimal process could be drawn as (Cr{sub 0.85}V{sub 0.15}){sub 2}(C{sub 0.57}N{sub 0.43}). Thermal processing precursors method shows the advantages of lower synthesis temperature, shorter period and finer particles when comparing with the conventional preparations. - Highlights: • Single phase of (Cr,V){sub 2}(C,N) powders were synthesized for the first time. • Precursors were used to prepared the powders by carbothermal

  2. Lattice mismatch modeling of aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Dongwon; Roy, Shibayan; Watkins, Thomas R.; Shyam, Amit

    2017-10-01

    We present a theoretical framework to accurately predict the lattice mismatch between the fcc matrix and precipitates in the multi-component aluminum alloys as a function of temperature and composition. We use a computational thermodynamic approach to model the lattice parameters of the multi-component fcc solid solution and θ'-Al2Cu precipitate phase. Better agreement between the predicted lattice parameters of fcc aluminum in five commercial alloys (206, 319, 356, A356, and A356 + 0.5Cu) and experimental data from the synchrotron X-ray diffraction (SXD) has been obtained when simulating supersaturated rather than equilibrium solid solutions. We use the thermal expansion coefficient of thermodynamically stable θ-Al2Cu to describe temperature-dependent lattice parameters of meta-stable θ' and to show good agreement with the SXD data. Both coherent and semi-coherent interface mismatches between the fcc aluminum matrix and θ' in Al-Cu alloys are presented as a function of temperature. Our calculation results show that the concentration of solute atoms, particularly Cu, in the matrix greatly affects the lattice mismatch

  3. Effect of varying Ga content in ZnO:GaN solid solution synthesized by solution combustion technique for photocatalytic applications

    Science.gov (United States)

    Menon, Sumithra Sivadas; Janani, R.; Baskar, K.; Gupta, Bhavana; Singh, Shubra

    2017-05-01

    ZnO:GaN (oxy)nitride solid solution has been established as the most efficient non-oxide photocatalyst for water splitting under visible irradiation with one step photoexcitation and also boasts a band gap tunability from 2.8 eV to 2.5 eV[1]. The solid solution of GaN in ZnO is formed by the intersubstitution of few of Zn/O ions by Ga/N ions, and this results in the introduction of new defect levels above the valence band which narrows the effective band gap enabling activity under visible region of spectra. In this work, we report the synthesis of ZnO:GaN solid solution by a solution combustion technique where metal nitrates and urea are used as precursors. The Zn/Ga ratio was varied from 16 to 1 in the precursors. The as synthesized samples were characterized as phase pure by X-ray diffraction, where the wurtzite structure was retained up to Zn/Ga ratio of 5. The Diffuse reflectance spectroscopy studies revealed that as the Ga content in the solid solution increases there is a reduction in band gap, from 2.9 eV to 2.4 eV. The reduced band gap of the samples facilitates its photocatalytic activity under visible region of the spectra as evaluated by photoelectrochemical measurements.

  4. Modifying Optical Properties of ZnO Films by Forming Zn[subscript 1-x] Co[subscript x]O Solid Solutions via Spray Pyrolysis

    Science.gov (United States)

    Bentley, Anne K.; Weaver, Gabriela C.; Russell, Cianan B.; Fornes, William L.; Choi, Kyoung-Shin; Shih, Susan M.

    2007-01-01

    A simple and cost-effective experiment for the development and characterization of semiconductors using Uv-vis spectroscopy is described. The study shows that the optical properties of ZnO films can be easily modified by forming Zn[subscript 1-x] Co[subscript x]O solid solutions via spray pyrolysis.

  5. Modeling of the solid-solution partitioning of heavy metals and arsenic in embanked flood plain soils of the rivers Rhine and Meuse

    NARCIS (Netherlands)

    Schröder, T.J.; Hiemstra, T.; Vink, J.P.M.

    2005-01-01

    The aim of this study is to predict the solid-solution partitioning of heavy metals in river flood plain soils. We compared mechanistic geochemical modeling with a statistical approach. To characterize the heavy metal contamination of embanked river flood plain soils in The Netherlands, we collected

  6. Immobilization of ZnS–AgInS2 Solid Solution Nanoparticles on ZnO Rod Array Electrodes and Their Photoresponse with Visible Light Irradiation

    National Research Council Canada - National Science Library

    Sasamura, Tetsuya; Okazaki, Ken-ichi; Tsunoda, Ryuta; Kudo, Akihiko; Kuwabata, Susumu; Torimoto, Tsukasa

    2010-01-01

    ZnS–AgInS2 solid solution (ZAIS) nanoparticles having elements of low toxicity were immobilized on thin ZnO rod array films, and the resulting film worked as an n-type semiconductor electrode for which the photoresponse varied...

  7. Conductivity and thermopower studies of bis-tetramethyltetraselenafulvalenium hexafluorophosphide, bis-tetramethyltetrathiafulvalenium hexafluorophosphide, and their solid solutions, (TMTSF1-xTMTTFx)2PF6

    DEFF Research Database (Denmark)

    Mortensen, Kell; Engler, E. M.

    1984-01-01

    The conductivity σ and the thermoelectric power S have been studied experimentally on the organic conductors bis-tetramethyltetraselenafulvalenium hexafluorophosphide [(TMTSF)2PF6] and bis-tetramethyltetrathiafulvalenium hexafluorophosphide [(TMTTF)2PF6] and their solid solutions: (TMTSF1-xTMTTFx)2...

  8. Pebble fabrication of super advanced tritium breeders using a solid solution of Li2+xTiO3+y with Li2ZrO3

    Directory of Open Access Journals (Sweden)

    Tsuyoshi Hoshino

    2016-12-01

    Full Text Available Lithium titanate with excess lithium (Li2+xTiO3+y is one of the most promising candidates among advanced tritium breeders for demonstration power plant reactors because of its good tritium release characteristics. However, the tritium breeding ratio (TBR of Li2+xTiO3+y is smaller than that of e.g., Li2O or Li8TiO6 because of its lower Li density. Therefore, new Li-containing ceramic composites with both high stability and high Li density have been developed. Thus, this study focused on the development of a solid solution with a new characteristic. The solid-solution pebbles of Li2+xTiO3+y with Li2ZrO3 (Li2+x(Ti,ZrO3+y, designated as LTZO, were fabricated by an emulsion method. The X-ray diffraction patterns of sintered LTZO pebbles are approximately the same as those of Li2+xTiO3+y pebbles, and no peaks attributable to Li2ZrO3 are observed. These results demonstrate that LTZO pebbles are not a two-phase material but rather a solid solution. Furthermore, LTZO pebbles were easily sintered under air. Thus, the LTZO solid solution is a candidate breeder material for super advanced (SA tritium breeders.

  9. Isotopically exchangeable phosphate in freshwater sediments: Effects of u.v.-irradiation, formaldehyde, solid/solution ratio, and pH on its experimental determination

    NARCIS (Netherlands)

    Vaas, L.H.; Comans, R.N.J.; Reith, J.M.M.; Weijden, C.H. van der; Das, H.A.

    The influence of bioactivities, solid/solution ratio and the pH on the isotopic exchangeability of phosphate in a freshwater sediment was investigated. From the comparison of the results obtained for the same sample in the presence or absence of formaldehyde, it is concluded that microorganisms

  10. Effects of heat treatment on mechanical and tribological properties of cobalt-base tribaloy alloys

    Science.gov (United States)

    Liu, Rong; Yao, Matthew X.; Patnaik, Prakash C.; Wu, Xijia

    2005-10-01

    Cobalt-base Tribaloy alloys are important wear-resistant materials, especially for high-temperature applications, because of the outstanding properties of the strengthened cobalt solid solution and the hard Laves intermetallic phase that make up the alloys. The Laves intermetallic phase is so abundant (35-70 vol.%) in these alloys that its presence governs all of the material properties. Heat treatment may alter the volume fraction, the size/shape, and the distribution of the Laves phase in the microstructures as well as the phase and structure of the cobalt solid solution, thus influencing the mechanical and tribological properties of the alloys. In this work, the effects of heat treatment on two cobalt-based Tribaloy alloys, T-400 and T-200, were studied. The former is a well-known Tribaloy alloy, and the latter is a newly developed one. These two alloys were heat treated in different conditions. The phases and microstructures of the alloys before and after the heat treatments were analyzed using x-ray and scanning electron microscopy. The mechanical and tribological properties of the alloys were investigated using a nano-indentation technique and a pin-on-disc tribometer, respectively.

  11. Basic research for alloy design of Nb-base alloys as ultra high temperature structural materials; Chokoon kozoyo niobuki gokin no gokin sekkei no tame no kisoteki kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Miura, E. [Tohoku University, Sendai (Japan); Yoshimi, K.; Hanada, S. [Tohoku Univ., Sendai (Japan). Research Inst. for Iron, Steel and Other Metals

    1997-02-01

    This paper describes an influence of additional elements on the high temperature deformation behavior of Nb-base solid solution alloys. Highly concentrated solid solution single crystals of Nb-Ta and Nb-Mo alloys were prepared. Compression test and strain rate sudden change test were conducted in the vacuum at temperatures ranging from 77 to 1773 K, to determine the strain rate sensitivity index. Yield stress of the Nb-Ta alloy was similar to that of Nb alloy at temperatures over 0.3{times}T{sub M}, where T{sub M} is fusing point of Nb. While, the yield stress increased with increasing the impurity oxygen concentration at temperatures below 0.3{times}T{sub M}. The yield stress became much higher than that of Nb alloy. The strain rate sensitivity index showed positive values in the whole temperature range. On the other hand, the yield stress of Nb-Mo alloy was higher than that of Nb alloy in the whole temperature range, and increased with increasing the Mo concentration. The strain rate sensitivity index showed negative values at the temperature range from 0.3{times}T{sub M} to 0.4{times}T{sub M}. It was found that serration occurred often for Nb-40Mo alloys. 1 ref., 4 figs., 1 tab.

  12. The contribution of dislocation - Impurities interaction to kinetics of martensitic transformation of quenched fcc Fe-Ni-Mo alloys

    NARCIS (Netherlands)

    Golovin, [No Value; Goncharov, S; Golovin, SA

    1996-01-01

    The kinetics of martensitic transformation in austenitic Fe-Ni-Mo alloys depends on the carbon content. Analysis of carbon redistribution between f.c.c. solid solution and dislocation has been carried out with the help of internal friction (amplitude and temperature effects) study and stress

  13. Calcium-magnesium carbonate solid solutions from Holocene conglomerate cements and travertines in the Coast Range of California

    Science.gov (United States)

    Barnes, I.; O'Neil, J.R.

    1971-01-01

    Two calcium-magnesium carbonate solid solutions form Holocene travertines and conglomerate cements in fresh water stream channels of the Coast Range of California. Calcite does not yield the {015} diffraction maximum. The {006} diffraction maximum is lacking over most of the range of composition of calcite. Calcite has compositions from CaCO3 to Ca0.5Mg0.5CO3. Dolomite yields both the {006} and {015} diffraction maxima over its entire composition range, Ca0.6Mg0.4CO3 to Ca0.5Mg0.5CO3. The Ca-Mg carbonates form in isotopic equilibrium and thermodynamic disequilibrium from dispersion of Ca2+-rich water into CO32--rich water within the alluvium. The stable isotope data suggest that all the Mg-rich carbonates are primary precipitates and not a result of Mg-substitution in precursor CaCO3. There is a correlation between ??C13 and Mg content of the carbonates which predicts a 5%. fractionation of C13 between dolomite and calcite at sedimentary temperatures. C14 is incorporated in Ca-Mg carbonates forming from C13-poor meteoric waters and C13-rich waters from Cretaceous sediments. C14 ages of the Ca-Mg carbonates are apparent, and cannot be corrected to absolute values. Solution rates of calcite decrease with increasing MgCO3 content; dolomite dissolves slower than any calcite. ?? 1971.

  14. Magnetic properties of HoCoC2, HoNiC2 and their solid solutions

    Science.gov (United States)

    Michor, H.; Steiner, S.; Schumer, A.; Hembara, M.; Levytskyy, V.; Babizhetskyy, V.; Kotur, B.

    2017-11-01

    Magnetic properties of single crystalline HoCoC2 and the evolution of magnetic and structural features in a series of polycrystalline solid solutions HoCo1-xNixC2 (0 ⩽ x ⩽ 1) are investigated by means of X-ray diffraction, magnetization, magnetic susceptibility and specific heat measurements. The crystal structures of all investigated samples refers to the CeNiC2-type structure (space group Amm 2 and Pearson symbol oS8). Non-isoelectronic substitution of Co by Ni causes a non-linear increase of the unit cell volume and especially a non-monotonous variation of the a and c lattice parameters as well as a pronounced reduction of the C-C bond length of carbon dimers. Temperature dependent magnetization and specific heat measurements reveal a crossover from a ferromagnetic for HoCoC2 with TC = 10.6 (1) K to an antiferromagnetic ground state for HoNiC2 with TN = 2.78 (6) K and a non-monotonous variation of the magnetic ordering temperature with a minimum at intermediate compositions. Crystalline electric field effects of HoCoC2 and HoNiC2 are analysed using combined thermodynamic and magnetic susceptibility data. The electrical resistivity of HoNiC2 displays a distinct anomaly near room temperature which indicates the formation of a charge density wave (CDW) state as earlier reported for several other rare earth nickel dicarbides.

  15. An analysis of the high-temperature phase structure of multiferroic solid solutions of the PFW–PT

    Directory of Open Access Journals (Sweden)

    Aleksandr A. Naberezhnov

    2016-10-01

    Full Text Available The temperature evolution of multiferroic solid solutions of the PFW–PT system, namely a (1–xPb(Fe2/3W1/3O3–(xPbTiO3 crystal structure where x = 0, 0.2, 0.3, has been studied by neutron powder diffraction in the region of the morphotropic phase boundary. The coexistence of cubic and tetragonal phases in the solutions with x = 0.2, 0.3 was found below T = 259 and 285K, respectively. As a result of the data treatment, the atom coordinates, the occupation factors and the temperature dependences of cell parameters were determined in the cubic perovskite phase. The refinement of the crystal structure in terms of ideal perovskite exhibited anomalously large Debye–Waller factors for the lead cations, indicating the appearance of random static displacements of these cations from the ideal perovskite (000 position. Using the split-ion model we estimated the value of Pb static shifts (∼0.1Å from their high-symmetry positions along the [110] direction. It was shown that these shifts decrease with increasing the PbTiO3 concentration.

  16. The LiBH4-LiI Solid Solution as an Electrolyte in an All-Solid-State Battery

    DEFF Research Database (Denmark)

    Sveinbjörnsson, Dadi Þorsteinn; Christiansen, Ane Sælland; Viskinde, Rasmus

    2014-01-01

    is compared with a cell with an identical electrode setup but a liquid electrolyte (1 M LiPF6 in EC:DMC). All measurements were carried out at a temperature of 60°C. For the all-solid-state cells, 81% of the theoretical discharge capacity is reached for a discharge rate of 10 μA, but a capacity fade of 1......The charge and discharge performance of an all-solid-state lithium battery with the LiBH4-LiI solid solution as an electrolyte is reported. Lithium titanate (Li4Ti5O12) was used as the positive electrode and lithium metal as the negative electrode. The performance of the all-solid-state cell...... the change in the discharge capacity of the cells and changes in the cell impedance over 200 charge-discharge cycles. This is expectedly due to the possible formation of passivating areas in the cell and/or loss of contact area between the electrolyte and the electrodes....

  17. Kinetics of the fcc → hcp Phase Transformation in Cu-Ge Solid Solutions Upon Isothermal Aging

    Science.gov (United States)

    Polatidis, E.; Zotov, N.; Bischoff, E.; Mittemeijer, E. J.

    2017-11-01

    The kinetics of the ζ-phase formation from a supersaturated α-Cu(Ge) solid solution ( i.e., transformation from the fcc crystal structure to the hcp crystal structure) containing 10.8 at. pct Ge [at isothermal temperatures of 573 K, 613 K, and 653 K (300 °C, 340 °C, and 380 °C)] were studied by X-ray diffraction (XRD) for phase fraction determination. Both in situ and ex situ annealing experiments were performed. The transformation kinetics were modeled on the basis of a versatile modular model. The transformation kinetics complied with a site-saturation nucleation mode and strongly anisotropic interface-controlled growth mode in association with a corresponding impingement mode: diffusion of Ge (towards the stacking faults, SFs) does not control the transformation rate. Transmission electron microscopy (TEM) investigations showed that segregation of Ge at the stacking faults (SFs) takes place (relatively fast) prior to the structural transformation (fcc → hcp).

  18. Characterization and magnetic properties of nanoparticles based on FePt solid solution with an oxide shell

    Energy Technology Data Exchange (ETDEWEB)

    Shpetnyi, I.; Kovalenko, A.S. [Sumy State University, Rimsky-Korsakov Street 2, 40007 Sumy (Ukraine); Klimenkov, M. [Institute for Applied Materials, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Protsenko, I.Yu. [Sumy State University, Rimsky-Korsakov Street 2, 40007 Sumy (Ukraine); Chernov, S.V. [Institute of Physics, University of Mainz, Staudingerweg 7, 55128 Mainz (Germany); Nepijko, S.A., E-mail: nepijko@uni-mainz.de [Institute of Physics, University of Mainz, Staudingerweg 7, 55128 Mainz (Germany); Elmers, H.J.; Schönhense, G. [Institute of Physics, University of Mainz, Staudingerweg 7, 55128 Mainz (Germany)

    2015-01-01

    We present the results of magnetic properties investigations of ferromagnetic nanoparticles which ensembled with ferromagnetic shell. The aim of this work is to study the connection of structure–phase composition and thermal treatment with the magnetic properties, partially, with the coercive force and the exchange bias field in a two-dimension spin system of core–shell type. It is found that the exchange bias field increases with the growth of the oxide shell thickness. This is realized by annealing in a dosed oxygen flow. The decrease of the coercive force with the increase of annealing temperature is connected with the concentration effect (the concentration of ferromagnetic particles decreases). - Highlights: • We investigated particles that have core–shell structure, where core material is a solid solution Fe{sub x}Pt{sub 1−x} and shell consists of γ-Fe{sub 2}O{sub 3} with spinel structure. • It is defined that exchange bias field increases with the increase of oxide shell thickness. • Coercive force after annealing decreases due to decrease of ferromagnetic particles concentration. • Analysis of exchange bias field and coercive force measurements for FePt systems of different effective thicknesses of components showed the possibility to control magnetic hardness of the studied system.

  19. Role of bond strength on the lattice thermal expansion and oxide ion conductivity in quaternary pyrochlore solid solutions.

    Science.gov (United States)

    Radhakrishnan, A N; Prabhakar Rao, P; Mahesh, S K; Thampi, D S Vaisakhan; Koshy, Peter

    2012-02-20

    Quaternary pyrochlore-type solid solutions, CaGdZrNb(1-x)Ta(x)O(7) (x = 0, 0.2, 0.4, 0.6, 0.8, 1), were prepared by a high-temperature ceramic route. The pyrochlore phases of the compounds were confirmed by powder X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy. The crystallographic parameters of the pyrochlore compounds were accurately determined by Rietveld analysis of the powder XRD data. The isovalent substitution of Ta in place of Nb at the B site can reveal the effect of chemical bonding on lattice thermal expansion and oxide ion conductivity because both Nb and Ta have the same ionic radius (0.64 Å). Lattice thermal expansion coefficients of the samples were calculated from high-temperature XRD measurements, and it was found that the thermal expansion coefficient decreases with substitution of Ta. Oxide ion conductivity measured by a two-probe method also shows the same trend with substitution of Ta, and this can be attributed to the high bond strength of the Ta-O bond compared to that of the Nb-O bond. Microstructural characterization using scanning electron microscopy proves that the size of the grains has a small effect on the oxide ion conductivity. Our studies established the role of chemical bonding in deciding the conductivity of pyrochlore oxides and confirmed that the 48f-48f mechanism of oxide ion conduction is dominant in pyrochlore oxides.

  20. A space-charge treatment of the increased concentration of reactive species at the surface of a ceria solid solution

    Energy Technology Data Exchange (ETDEWEB)

    Zurhelle, Alexander F.; Souza, Roger A. de [Institute of Physical Chemistry, RWTH Aachen University (Germany); Tong, Xiaorui; Mebane, David S. [Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV (United States); Klein, Andreas [Institute of Materials Science, TU Darmstadt (Germany)

    2017-11-13

    A space-charge theory applicable to concentrated solid solutions (Poisson-Cahn theory) was applied to describe quantitatively as a function of temperature and oxygen partial pressure published data obtained by in situ X-ray photoelectron spectroscopy (XPS) for the concentration of Ce{sup 3+} (the reactive species) at the surface of the oxide catalyst Ce{sub 0.8}Sm{sub 0.2}O{sub 1.9}. In contrast to previous theoretical treatments, these calculations clearly indicate that the surface is positively charged and compensated by an attendant negative space-charge zone. The high space-charge potential that develops at the surface (>0.8 V) is demonstrated to be hardly detectable by XPS measurements because of the short extent of the space-charge layer. This approach emphasizes the need to take into account defect interactions and to allow deviations from local charge neutrality when considering the surfaces of oxide catalysts. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Structural Behaviour of Solid Solutions in the NdAlO3-SrTiO3 System

    Science.gov (United States)

    Ohon, Natalia; Stepchuk, Roman; Blazhivskyi, Kostiantyn; Vasylechko, Leonid

    2017-02-01

    Single-phase mixed aluminates-titanates Nd1- x Sr x Al1- x Ti x O3 ( x = 0.3 ÷ 0.9) were prepared from stoichiometric amounts of constituent oxides Nd2O3, Al2O3, TiO2 and strontium carbonate SrCO3 by solid-state reaction technique in air at 1773 K. Crystal structure parameters of Nd1- x Sr x Al1- x Ti x O3 were refined by full-profile Rietveld refinement in space groups R overline{3} c ( x = 0.3, 0.5, 0.7 and 0.8) and Pm overline{3} m ( x = 0.9). Comparison of the obtained structural parameters with the literature data for the end members of the system NdAlO3 and SrTiO3 revealed formation of two kinds of solid solutions Nd1-xSrxAl1-xTixO3 with the cubic and rhombohedral perovskite structure. Morphotropic rhombohedral-to-cubic phase transition in Nd1-xSrxAl1-xTixO3 series occurs at x = 0.84. Based on the results obtained as well as the literature data for the parent compounds, the tentative phase diagram of the NdAlO3-SrTiO3 pseudo-binary system have been constructed.

  2. Microstructure and magnetic properties of mechanically alloyed FeSiBAlNi (Nb) high entropy alloys

    Science.gov (United States)

    Wang, Jian; Zheng, Zhou; Xu, Jing; Wang, Yan

    2014-04-01

    In this paper, the effects of milling duration and composition on the microstructure and magnetic properties of equi-atomic FeSiBAlNi and FeSiBAlNiNb high entropy alloys during mechanical alloying have been investigated using X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, transmission electron microscopy and alternating gradient magnetometry. The amorphous high entropy alloys have been successfully fabricated using the mechanical alloying method. The results show that the Nb addition prolongs the milling time for the formation of the fully FeSiBAlNi amorphous phase and decreases the glass forming ability. However, FeSiBAlNiNb amorphous high entropy alloy has the higher thermal stability and heat resisting properties. Moreover, the as-milled FeSiBAlNi(Nb) powders are soft-magnetic materials indicated by their low coercivity. The saturation magnetization of the as-milled FeSiBAlNi(Nb) powders decreases with prolonging of the milling time and shows the lowest value when the amorphous high entropy alloys are formed. It suggests that the as-milled products with solid solution phases show the better soft-magnetic properties than those with fully amorphous phases. The Nb addition does not improve the soft-magnetic properties of the FeSiBAlNi high entropy alloys. Rather, both amorphous high entropy alloys have similar soft-magnetic properties after a long milling time.

  3. Estudio de Relaciones Espectrales V/H Asociado al Sistema de Fallas de Quito

    OpenAIRE

    López Moreno, Eduardo Sebastián

    2016-01-01

    La ciudad de Quito se asienta sobre un sistema de fallas ciegas inversas, el modelo neotectónico considera 5 segmentos de fallas que se extiende aproximadamente a lo largo de 60 km., sin embargo no se tiene un conocimiento adecuado del peligro sísmico asociado a este sistema de fallas para la componente vertical del movimiento del suelo. En este estudio, se van a determinar relaciones espectrales V/H utilizando los modelos de movimiento fuerte del suelo correspondientes al programa Next Gener...

  4. Ab initio calculation of excess properties of La{sub 1−x}(Ln,An){sub x}PO{sub 4} solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yan [Institute of Energy and Climate Research (IEK-6), Forschungszentrum Jülich, Wilhelm-Johnen-Strasse, 52425 Jülich (Germany); JARA High-Performance Computing, Schinkelstrasse 2, 52062 Aachen (Germany); Kowalski, Piotr M., E-mail: p.kowalski@fz-juelich.de [Institute of Energy and Climate Research (IEK-6), Forschungszentrum Jülich, Wilhelm-Johnen-Strasse, 52425 Jülich (Germany); JARA High-Performance Computing, Schinkelstrasse 2, 52062 Aachen (Germany); Blanca-Romero, Ariadna [Institute of Energy and Climate Research (IEK-6), Forschungszentrum Jülich, Wilhelm-Johnen-Strasse, 52425 Jülich (Germany); JARA High-Performance Computing, Schinkelstrasse 2, 52062 Aachen (Germany); Vinograd, Victor [Institute of Energy and Climate Research (IEK-6), Forschungszentrum Jülich, Wilhelm-Johnen-Strasse, 52425 Jülich (Germany); Institute of Geoscience, Goethe Universität Frankfurt am Main, Altenhöferallee 1, 60438 Frankfurt (Germany); Bosbach, Dirk [Institute of Energy and Climate Research (IEK-6), Forschungszentrum Jülich, Wilhelm-Johnen-Strasse, 52425 Jülich (Germany); JARA High-Performance Computing, Schinkelstrasse 2, 52062 Aachen (Germany)

    2014-12-15

    We used ab initio computational approach to predict the excess enthalpy of mixing and the corresponding regular/subregular model parameters for La{sub 1−x}Ln{sub x}PO{sub 4} (Ln=Ce,…, Tb) and La{sub 1−x}An{sub x}PO{sub 4} (An=Pu, Am and Cm) monazite-type solid solutions. We found that the regular model interaction parameter W computed for La{sub 1−x}Ln{sub x}PO{sub 4} solid solutions matches the few existing experimental data. Within the lanthanide series W increases quadratically with the volume mismatch between LaPO{sub 4} and LnPO{sub 4} endmembers (ΔV=V{sub LaPO{sub 4}}−V{sub LnPO{sub 4}}), so that W(kJ/mol)=0.618(ΔV(cm{sup 3}/mol)){sup 2}. We demonstrate that this relationship also fits the interaction parameters computed for La{sub 1−x}An{sub x}PO{sub 4} solid solutions. This shows that lanthanides can be used as surrogates for investigation of the thermodynamic mixing properties of actinide-bearing solid solutions. - Highlights: • The excess enthalpies of mixing for monazite-type solid solutions are computed. • The excess enthalpies increase with the endmembers volume mismatch. • The relationship derived for lanthanides is transferable to La{sub 1−x}An{sub x}PO{sub 4} systems.

  5. Kinetic process of mechanical alloying in Fe50Cu50

    DEFF Research Database (Denmark)

    Huang, J.Y.; Jiang, Jianzhong; Yasuda, H.

    1998-01-01

    It is shown that mechanical alloying in the immiscible Fe-Cu system is governed by the atomic shear event and shear-induced diffusion process. We found that an alpha-to-gamma phase transformation, as evidenced by the Nishiyama-Wasserman orientation relationship, occurs by simultaneous shearing...... structures, until a complete fee Fe-Cu solid solution is formed. The results provide significant insight into the understanding of recent experiments showing that chemical mixing of immiscible elements can bd induced by mechanical alloying. [S0163-1829(98)51342-2]....

  6. Thermal analytical investigations of the magnesium alloy AZ91

    Directory of Open Access Journals (Sweden)

    K.N. Braszczyńska - Malik

    2007-04-01

    Full Text Available The results of thermal derivative analysis (TDA, differential scanning calorimetric (DSC measurements and microstructure investigations of commercial AZ91 magnesium alloy are presented. The performed examinations allowed to determine the microstructure after solidification process and also precipitation process during continuous heating of supersaturated solid solution. The α-phase and α+γ semi-divorced eutectic were observed in as-cast material, whereas both discontinuous and continuous precipitates of γ phase were revealed after heating supersaturated AZ91 alloy.

  7. Design of High-Entropy Alloy: A Perspective from Nonideal Mixing

    Science.gov (United States)

    He, Q. F.; Ding, Z. Y.; Ye, Y. F.; Yang, Y.

    2017-11-01

    Since the advent in 2004, high-entropy alloys (HEAs) have been attracting a great deal of research interest worldwide. Being deemed as a major paradigmatic shift, the design of HEAs without base elements poses challenges to the existing thermodynamic models and theories that were long established for traditional alloys, one of which is related to the thermodynamic mechanisms for the formation of random solid solution in a concentrated multicomponent alloy. In this article, we discuss the design of HEAs from the perspective of correlated mixing (nonideal mixing of atoms with interatomic correlations). In a quantitative manner, we can show that the formation of a random solid solution in HEAs depends not only on the number of constituent elements but also on the alloy's melting/processing temperature and on various interatomic correlations. Through the correlated mixing rule, we further demonstrate a strategy to screen out equiatomic alloys with the thermodynamic characteristics close to those of random solid solutions from an expanded library of 20 candidate elements.

  8. Microstructure, a limiting parameter for determining the engineering range of compositions for light alloys: The Al-Cu-Si system

    Energy Technology Data Exchange (ETDEWEB)

    Plaza, D.; Pero-Sanz, J.A. [Univ. Politecnica, Madrid (Spain); Asensio, J.; Verdeja, J.I. [Univ. de Oviedo (Spain)

    1998-03-01

    Twelve as-cast alloys of the Al-Cu-Si ternary system were investigated. In all the cases, the microstructural phases observed were: {alpha} solid solution of Cu and Si in Al, CuAl{sub 2} ({theta} phase), and silicon crystals. The morphology and distribution of the {theta} and Si brittle constituents limit the percentages of Cu and Si added in the composition ranges of these commercial alloys.

  9. Clean Grain Boundary Found in C14/Body-Center-Cubic Multi-Phase Metal Hydride Alloys

    OpenAIRE

    Hao-Ting Shen; Kwo-Hsiung Young; Tiejun Meng; Bendersky, Leonid A

    2016-01-01

    The grain boundaries of three Laves phase-related body-center-cubic (bcc) solid-solution, metal hydride (MH) alloys with different phase abundances were closely examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and more importantly, electron backscatter diffraction (EBSD) techniques. By using EBSD, we were able to identify the alignment of the crystallographic orientations of the three major phases in the alloys (C14, bcc, and B2 structures). This finding...

  10. From composites to solid solutions: modeling of ionic conductivity in the CaF2-BaF2 system.

    Science.gov (United States)

    Zahn, Dirk; Heitjans, Paul; Maier, Joachim

    2012-05-14

    By using calcium fluorite and barium fluorite as test materials, we demonstrated that homovalent "dopants" can greatly affect ionic conductivity through locally changing the defect density. Whilst this doping is a state-of-the-art effect in the case of dopants that replace native ions of different charge (heterovalent dopants), it is a rather surprising effect at a first glance for substitutional dopants of the same charge; here, the phenomenon is not electrostatic, but elastic in nature. As a consequence of size mismatch, the smaller Ca atoms in the BaF(2) lattice favored the formation of interstitial sites that were located close to the Ca atoms, whilst doping larger Ba species into the CaF(2) phase favored vacancy formation. In terms of conductivity, and in agreement with the different mobilities, the first doping effect was favorable, whilst the other decreased conductivity. The concentration effects were formalized by a heterogeneous Frenkel reaction that was distinguished from the mean Frenkel reaction by additional (elastic) trapping that became more pronounced the lower the temperature. It was very revealing to relate this phenomenon to CaF(2)-BaF(2) multilayers and composites. In very general terms, these effects in the solid solutions were understood as being the atomistic limit of the interfacial charge-transfer that occurred at the hetero-interface of the crystallites or films, and reflected the transition from heterogeneous doping (higher-dimensional doping) to homogeneous doping (zero-dimensional doping). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Computational Analysis of Material Flow During Friction Stir Welding of AA5059 Aluminum Alloys

    Science.gov (United States)

    2011-01-01

    interfaces alone. 233Li et al. (Ref 25) carried out a series of FSW experiments 234involving either dissimilar aluminum-alloy grades or alumi - 235num/copper...within the weld region in a 317variety of solid-solution strengthened and age-hardened alumi - 318num- and titanium-based alloys. Since the main emphasis of...o o f U N C O R R E C T E D P R O O F 495 3.2 Material Models 496 3.2.1 Tool Material. FSW tools used for joining alumi - 497 num alloys are typically

  12. Laser assisted high entropy alloy coating on aluminum: Microstructural evolution

    Energy Technology Data Exchange (ETDEWEB)

    Katakam, Shravana; Joshi, Sameehan S.; Mridha, Sanghita; Mukherjee, Sundeep; Dahotre, Narendra B., E-mail: Narendra.Dahotre@unt.edu [Department of Materials Science and Engineering, University of North Texas, 1150 Union Circle, 305310 Denton, Texas 76203-5017 (United States)

    2014-09-14

    High entropy alloy (Al-Fe-Co-Cr-Ni) coatings were synthesized using laser surface engineering on aluminum substrate. Electron diffraction analysis confirmed the formation of solid solution of body centered cubic high entropy alloy phase along with phases with long range periodic structures within the coating. Evolution of such type of microstructure was a result of kinetics associated with laser process, which generates higher temperatures and rapid cooling resulting in retention of high entropy alloy phase followed by reheating and/or annealing in subsequent passes of the laser track giving rise to partial decomposition. The partial decomposition resulted in formation of precipitates having layered morphology with a mixture of high entropy alloy rich phases, compounds, and long range ordered phases.

  13. Microstructure of MCMgAl12Zn1 magnesium alloy

    Directory of Open Access Journals (Sweden)

    Dobrzański L. A.

    2007-01-01

    Full Text Available In this paper is presented the structure of the cast magnesium alloys as cast state and after heat treatment cooled with different cooling rate, depending on the cooling medium (furnace, water, air. For investigations samples in shape of 250x150x25 mm plates were used. The structure have been study in the light microscope, scanning electron microscope equipped with an electron back scattering facility. The effects of the addition of Al on the microstructure were also studied. In the analysed alloys a structure of α solid solution and fragile phase β(Mg17Al12 occurred mainly on grain borders as well as eutectic and phase with Mn, Fe and Si. Investigation are carried out for the reason of chemical composition influence and precipitation processes influence to the structure and mechanical properties of the magnesium cast alloys with different chemical composition in as cast alloys and after heat treatment.

  14. Hydrogen Production from Water by Photolysis, Sonolysis and Sonophotolysis with Solid Solutions of Rare Earth, Gallium and Indium Oxides as Heterogeneous Catalysts

    Directory of Open Access Journals (Sweden)

    Marta Penconi

    2015-07-01

    Full Text Available In this work, we present the hydrogen production by photolysis, sonolysis and sonophotolysis of water in the presence of newly synthesized solid solutions of rare earth, gallium and indium oxides playing as catalysts. From the experiments of photolysis, we found that the best photocatalyst is the solid solution Y0.8Ga0.2InO3 doped by sulphur atoms. In experiments of sonolysis, we optimized the rate of hydrogen production by changing the amount of water, adding ethanol and tuning the power of our piezoelectric transducer. Finally, we performed sonolysis and sonophotolysis experiments in the presence of S:Y0.8Ga0.2InO3 finding a promising synergistic effect of UV-visible electromagnetic waves and 38 kHz ultrasound waves in producing H2.

  15. Synthesis of solid solutions of Dy xBi 2-xO 3 with x=0, 1 and 2: Structural, optical and ac impedance analysis

    Science.gov (United States)

    Iyyapushpam, S.; Chithra lekha, P.; Pathinettam Padiyan, D.

    2010-01-01

    Dysprosium hydroxide, bismuth hydroxide and mixed dysprosium bismuth hydroxide are prepared in the form of a gel by means of chemical precipitation technique. A simple gel to crystalline conversion technique has been followed by means of refluxing process. The synthesized hydroxides are characterized by thermogravimetry and differential thermal analysis. The formed hydroxides are converted into its oxides by calcining at a temperature of 700 °C for 2 h and solid solutions of Dy xBi 2-xO 3 with x=0, 1 and 2 are formed. The hydroxides and oxides of these solid solutions are investigated by means of XRD and found to be polycrystalline in nature. The Nyquist plot shows a single relaxation process. The enhanced conductivity is observed in dysprosium-based oxides and hydroxides. The optical band gap energy is in agreement with the ac conductivity values.

  16. Structure, elastic stiffness, and hardness of Os 1- xRu xB 2 solid solution transition-metal diborides

    KAUST Repository

    Kanoun, Mohammed

    2012-05-31

    On the basis of recent experiments, the solid solution transition-metal diborides were proposed to be new ultra-incompressible hard materials. We investigate using density functional theory based methods the structural and mechanical properties, electronic structure, and hardness of Os 1-xRu xB 2 solid solutions. A difference in chemical bonding occurs between OsB 2 and RuB 2 diborides, leading to significantly different elastic properties: a large bulk, shear moduli, and hardness for Os-rich diborides and relatively small bulk, shear moduli, and hardness for Ru-rich diborides. The electronic structure and bonding characterization are also analyzed as a function of Ru-dopant concentration in the OsB 2 lattice. © 2012 American Chemical Society.

  17. Effect of Heat Treatment on the Lithium Ion Conduction of the LiBH4–LiI Solid Solution

    DEFF Research Database (Denmark)

    Sveinbjörnsson, Dadi Þorsteinn; Mýrdal, Jón Steinar Garðarsson; Blanchard, Didier

    2013-01-01

    The LiBH4–LiI solid solution is a good Li+ conductor and a promising crystalline electrolyte for all-solid-state lithium based batteries. The focus of the present work is on the effect of heat treatment on the Li+ conduction. Solid solutions with a LiI content of 6.25–50% were synthesized by high......, resulting in conductivities exceeding 0.1 mS/cm at 30 °C and 10 mS/cm at 140 °C. It was found that the formation of defect-rich microstructures during ball milling increased the specific conductivities of these compounds significantly. The phase transition temperatures between the orthorhombic and hexagonal...

  18. Syntheses and high temperature phase transformation of alunite-natroalunite solid solution series. Myobanseki-natlium myobanseki koyotai no gosei to koon sohenka

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, M. (Kagoshima University, Kagoshima (Japan). Faculty of Agriculture); Shimoda, S. (University of Tsukuba, Tsukuba (Japan). Institute of Geoscience); Tomita, K. (Kgoshima University, Kgoshima (Japan). Faculty of Science)

    1991-05-01

    This paper explains the syntheses of the alunite-natroalunite solid solution series and its mineralogical properties, precipitation condition and high temperature phase transformations by heat treatment. The alunite-natroalunite solid solution series were synthesized and deposited by precipitation from mixed solutions of potassium sulfate, sodium sulfate and aluminuim sulfate for reaction of two days at boiling temperature under atmospheric pressure. The K ions in the initial solution were preferentially taken into the structure during crystallization of the alunite, and amounts of products suddenly decreased with decreasing K mol percent of the solution. Structural changes of alunites were observed by the thermal treatment. At 530 degrees C, formation of KAL (SO {sub 2}){sub 2} from alunite and Al {sub 2} (SO {sub 4}){sub 3} from natroalunite occurred simultaneously with the removal of OH ions. 22 refs., 13 figs., 7 tabs.

  19. Electronic structures of anatase (TiO2)1-x(TaON)x solid solutions: a first-principles study.

    Science.gov (United States)

    Dang, Wenqiang; Chen, Hungru; Umezawa, Naoto; Zhang, Junying

    2015-07-21

    Sensitizing wide band gap photo-functional materials under visible-light irradiation is an important task for efficient solar energy conversion. Although nitrogen doping into anatase TiO2 has been extensively studied for this purpose, it is hard to increase the nitrogen content in anatase TiO2 because of the aliovalent nitrogen substituted for oxygen, leading to the formation of secondary phases or defects that hamper the migration of photoexcited charge carriers. In this paper, electronic structures of (TiO2)1-x(TaON)x (0 ≤ x ≤ 1) solid solutions, in which the stoichiometry is satisfied with the co-substitution of Ti for Ta along with O for N, are investigated within the anatase crystal structure using first-principles calculations. Our computational results show that the solid solutions have substantially narrower band gaps than TiO2, without introducing any localized energy states in the forbidden gap. In addition, in comparison with the pristine TiO2, the solid solution has a direct band gap when the content of TaON exceeds 0.25, which is advantageous to light absorption. The valence band maximum (VBM) of the solid solutions, which is mainly composed of N 2p states hybridized with O 2p, Ti 3d or Ta 5d orbitals, is higher in energy than that of pristine anatase TiO2 consisting of non-bonding O 2p states. On the other hand, incorporating TaON into TiO2 causes the formation of d-d bonding states through π interactions and substantially lowers the conduction band minimum (CBM) because of the shortened distance between some metal atoms. As a result, the anatase (TiO2)1-x(TaON)x is expected to become a promising visible-light absorber. In addition, some atomic configurations are found to possess exceptionally narrow band gaps.

  20. Luminescent properties of solid solutions in the PbF2-Euf3 system and lead fluoroborate glass ceramics doped with Eu3+ ions

    Science.gov (United States)

    Sevostjanova, T. S.; Khomyakov, A. V.; Mayakova, M. N.; Voronov, V. V.; Petrova, O. B.

    2017-11-01

    Lead fluoroborate glasses doped with Eu3+ are synthesized, studied, and used to produce glassceramics by heat treatment. The structure of glass-ceramics is determined by X-ray diffraction. The optical, mechanical, and luminescent properties of the glass-ceramics are studied. The structure and spectral-luminescent properties of solid solutions in the PbF2-EuF3 system obtained by both solid-phase reaction and coprecipitation from solutions are investigated.

  1. Influence of heat treatment on microstructure and mechanical properties of as-cast Mg–8Li–3Al–2Zn–xY alloy with duplex structure

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jiong [National Engineering Research Center of Light Alloy Net Forming and Key State Laboratory of Metal Matrix Composite, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Li, Zhongquan [Shanghai Spaceflight Precision Machinery Institute, Shanghai 201600 (China); Liu, Wencai, E-mail: liuwc@sjtu.edu.cn [National Engineering Research Center of Light Alloy Net Forming and Key State Laboratory of Metal Matrix Composite, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Zhang, Jie; Zhang, Liang [National Engineering Research Center of Light Alloy Net Forming and Key State Laboratory of Metal Matrix Composite, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Tian, Ying [Shanghai Spaceflight Precision Machinery Institute, Shanghai 201600 (China); Wu, Guohua [National Engineering Research Center of Light Alloy Net Forming and Key State Laboratory of Metal Matrix Composite, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2016-07-04

    In this study, the microstructure evolution and mechanical properties of as-cast Mg–8Li–3Al–2Zn–0.5Y alloy during solid solution treatment from 300 °C to 450 °C were firstly investigated, and then the effect of Y content (from 0.5 wt% to 1.5 wt%) on the age softening of solid solution treated Mg–8Li–3Al–2Zn alloy was also analyzed. The results show that the as-cast Mg–8Li–3Al–2Zn–0.5Y alloy mainly consists of α-Mg, β-Li, Al{sub 2}Y and AlLi phases. With the increase of solid solution temperature from 300 °C to 450 °C for as-cast Mg–8Li–3Al–2Zn–0.5Y alloy, the AlLi phase is decomposed and the atoms of Al and Li dissolve into the matrix gradually. The hardness, yield strength and ultimate tensile strength of the tested alloy are increased dramatically; however, the ductility is relatively decreased. Meanwhile, the room temperature aging treated Mg–8Li–3Al–2Zn–0.5Y has age hardening during initial time, and the addition of Y is helpful to the thermal stability of Mg–8Li–3Al–2Zn alloy. In addition, the fracture behavior and strengthening mechanism of the studied alloys were also investigated systematically.

  2. Drastic lowering of the order-disorder phase transition temperatures in Zr1-xMxW2O8-y(M=Sc,Y,In) solid solutions

    Science.gov (United States)

    Yamamura, Yasuhisa; Nakajima, Noriyuki; Tsuji, Toshihide; Kojima, Ayumi; Kuroiwa, Yoshihiro; Sawada, Akikatsu; Aoyagi, Shinobu; Kasatani, Hirofumi

    2004-09-01

    ZrW2O8 undergoes an order-disorder phase transition associated with the orientational disordering of the WO4 tetrahedra at 440K . We have showed previously that the phase transition temperatures of Zr1-xMxW2O8-y(M=Sc,Y,In) solid solutions are decreased by a maximum of 80K with only 4% trivalent Sc content. In order to understand the drastic composition dependence on the transition temperature, precise x-ray diffraction experiments on the solid solutions were performed by using a synchrotron radiation. The results provided the evidence of the strong correlation between the phase transition temperature and the number of WO4 units with the ordered orientation. A model was proposed to interpret the drastic composition dependence on the transition temperature, by considering the existence of a local region including the WO4 pairs with the orientational disorder in Zr1-xMxW2O8-y(M=Sc,Y,In) . The local region has the crystal structure of the high-temperature phase in a nonequilibrium state, and spreads out around the substituted trivalent cations. The size of the local region was estimated to be a few unit cells. The local regions play just like nonmagnetic impurities in a site-diluted magnetic system, leading to drastic lowering of the phase transition temperatures in Zr1-xMxW2O8-y solid solutions.

  3. Unexpected formation of scheelite-structured Ca1-xCdxWO4 (0 ≤ x ≤ 1) continuous solid solutions with tunable photoluminescent and electronic properties.

    Science.gov (United States)

    Wang, Yunjian; Wu, Changjiang; Geng, Lei; Chen, Shifu

    2017-08-30

    Design of a solid solution with tunable functionality is an attractive strategy toward realizing novel devices with multi-functionalities. In this work, a series of Ca1-xCdxWO4 solid solutions in the entire range 0 ≤ x ≤ 1 with tetragonal scheelite structure have been successfully prepared for the first time. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and Fourier transform Raman (FT-Raman) spectroscopies indicated that all the nanocrystals have a tetragonal scheelite structure without wolframite phase. Structural refinement data revealed that the lattice volume decreased with the replacement of Ca2+ by Cd2+ ions. UV-Vis diffuse reflectance spectra indicated that optical band gap reduced with the replacement of Ca2+ by Cd2+ ions. Scanning electron microscopic (SEM) images showed that morphologies of the nanocrystals changed with the chemical compositions. The structure evolution of the solid solutions was further investigated by high-resolution transmission electron microscopy (HRTEM). Moreover, the influence of chemical compositions on the photoluminescent and electric performance has been performed and discussed. The reported synthetic approach and findings reported here are important to understand the structure and structure-property relation of scheelite-structured tungstate and molybdate compounds, which has potential applications in the design of other kinds of novel functional materials.

  4. Structural determination of new solid solutions [Y2-x Mx ][Sn2-x Mx ]O7-3x/2 (M = Mg or Zn by Rietveld method

    Directory of Open Access Journals (Sweden)

    Mohamed Douma

    2010-12-01

    Full Text Available New [Y2-x Mx][Sn2-x Mx]O7-3x/2 (0 ≤x≤ 0.30 for M = Mg and 0 ≤x≤ 0.36 for M = Zn solid solutions with the pyrochlore structure were synthesized via high-temperature solid-state reaction method. Powder X-ray diffraction (PXRD patterns and Fourier transform infrared (FT-IR spectra showed that these materials are new non-stoichiometric solid solutions with the pyrochlore type structure. The structural parameters for the solids obtained were successfully determined by Rietveld refinement based on the analysis of the PXRD diagrams. Lattice parameter (a of these solid solutions decreases when x increases in both series. All samples obtained have the pyrochlore structure Fd-3m, no. 227 (origin at center -3m with M2+ (M = Mg2+ or Zn2+ cations in Y3+ and Sn4+ sites, thus creating vacancies in the anionic sublattice.

  5. Facile Synthesis of ZnxCd1-xS Solid Solution Microspheres through Ultrasonic Spray Pyrolysis for Improved Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Jianhui Huang

    2017-01-01

    Full Text Available Nanocrystal ZnxCd1-xS solid solutions were successfully prepared using a facile and reproducible method of ultrasonic spray pyrolysis with Cd(Ac2·2H2O, ZnCl2, and thiourea as precursors. Scanning electron microscopy and transmission electron microscopy images show that the prepared particles possess microspherical morphology. The band gaps of the solid solutions can be tuned by changing the constituent stoichiometries of Cd and Zn. The X-ray diffraction peaks gradually shift to small angle, and the absorption edge shifts to long wavelength with increasing Cd molar fraction in the solid solution. The sample prepared at the Cd/Zn ratio of 1 : 1 displays the optimal activity by using the photocatalytic degradation of methyl orange in the aqueous solution as model reactions under visible light irradiation. This study provides an effective route to prepare spherical ternary photocatalysts with mesoporous structure for further investigations and practical applications.

  6. DENSITY-FUNCTIONAL STUDY OF U-Mo AND U-Zr ALLOYS

    Energy Technology Data Exchange (ETDEWEB)

    Landa, A; Soderlind, P; Turchi, P A

    2010-11-01

    Density-functional theory previously used to describe phase equilibria in U-Zr alloys [A. Landa, P. Soederlind, P.E.A. Turchi, J. Alloys Comp. 478 (2009) 103-110] is extended to investigate the ground-state properties of U-Mo solid solutions. We discuss how the heat of formation in both alloys correlates with the charge transfer between the alloy components, and how the specific behavior of the density of states in the vicinity of the Fermi level promotes the stabilization of the U{sub 2}Mo compound. Our calculations prove that, due to the existence of a single {gamma}-phase over the typical fuel operation temperatures, {gamma}-U-Mo alloys should indeed have much lower constituent redistribution than {gamma}-U-Zr alloys for which binodal decomposition causes a high degree of constituent redistribution.

  7. Evidence on unusual way of cocaine smuggling: cocaine-polymethyl methacrylate (PMMA) solid solution--study of clandestine laboratory samples.

    Science.gov (United States)

    Gostic, T; Klemenc, S

    2007-07-04

    An abandoned clandestine laboratory was seized in Slovenia. All confiscated exhibits were analysed in a forensic laboratory, where the following analytical methods were applied: capillary gas chromatography coupled with mass spectrometry (GC-MS) combined also by solid-phase micro extraction (SPME) and pyrolysis (Py) technique, Fourier transform infrared spectrometry (FTIR) and scanning electron microscopy with energy dispersive X-ray detector (SEM-EDX). The most interesting analytical findings can be summarised as follows: at the crime scene some plastic pieces, which contained cocaine dissolved (as solid solution) in polymethyl methacrylate-plexiglass (PMMA), were found. The highest cocaine concentration measured in the plastic sample was about 15% by weight. Two larger lumps of material (12 and 3 kg) were composed mainly of PMMA and CaCO3 and contained only 0.4 and 0.5% of cocaine, respectively. As for the low cocaine concentration, we assume that those two lumps of material represent discarded waste product--residue after the isolation of cocaine from plastic. Higher quantities of pure solvents (41 l) and solvent mixtures (87 l) were seized. We identified three types of pure solvents (acetone, gasoline and benzine) and two different types of solvent mixtures (benzine/acetone and gasoline/acetone). The total seized volume (87 l) of solvent mixtures holds approximately 395 g of solid residue formed mainly of PMMA and cocaine. Obviously solvent mixtures were used for isolation of cocaine from the plastic. Small quantities of relatively pure cocaine base were identified on different objects. There were two cotton sheets, most probably used for filtration. One sheet had traces of cocaine base (76% purity) on the surface, while cocaine in hydrochloride form (96%) was identified on the other sheet. GC-MS analyses of micro traces isolated from analytical balances showed the presence of cocaine and some common adulterants: phenacetine, lidocaine and procaine. A cocaine

  8. Searching for Next Single-Phase High-Entropy Alloy Compositions

    Directory of Open Access Journals (Sweden)

    David E. Alman

    2013-10-01

    Full Text Available There has been considerable technological interest in high-entropy alloys (HEAs since the initial publications on the topic appeared in 2004. However, only several of the alloys investigated are truly single-phase solid solution compositions. These include the FCC alloys CoCrFeNi and CoCrFeMnNi based on 3d transition metals elements and BCC alloys NbMoTaW, NbMoTaVW, and HfNbTaTiZr based on refractory metals. The search for new single-phase HEAs compositions has been hindered by a lack of an effective scientific strategy for alloy design. This report shows that the chemical interactions and atomic diffusivities predicted from ab initio molecular dynamics simulations which are closely related to primary crystallization during solidification can be used to assist in identifying single phase high-entropy solid solution compositions. Further, combining these simulations with phase diagram calculations via the CALPHAD method and inspection of existing phase diagrams is an effective strategy to accelerate the discovery of new single-phase HEAs. This methodology was used to predict new single-phase HEA compositions. These are FCC alloys comprised of CoFeMnNi, CuNiPdPt and CuNiPdPtRh, and HCP alloys of CoOsReRu.

  9. Effect of Boron Doping on Cellular Discontinuous Precipitation for Age-Hardenable Cu–Ti Alloys

    Directory of Open Access Journals (Sweden)

    Satoshi Semboshi

    2015-06-01

    Full Text Available The effects of boron doping on the microstructural evolution and mechanical and electrical properties of age-hardenable Cu–4Ti (at.% alloys are investigated. In the quenched Cu–4Ti–0.03B (at.% alloy, elemental B (boron is preferentially segregated at the grain boundaries of the supersaturated solid-solution phase. The aging behavior of the B-doped alloy is mostly similar to that of conventional age-hardenable Cu–Ti alloys. In the early stage of aging at 450 °C, metastable β′-Cu4Ti with fine needle-shaped precipitates continuously form in the matrix phase. Cellular discontinuous precipitates composed of the stable β-Cu4Ti and solid-solution laminates are then formed and grown at the grain boundaries. However, the volume fraction of the discontinuous precipitates is lower in the Cu–4Ti–0.03B alloy than the Cu–4Ti alloy, particularly in the over-aging period of 72–120 h. The suppression of the formation of discontinuous precipitates eventually results in improvement of the hardness and tensile strength. It should be noted that minor B doping of Cu–Ti alloys also effectively enhances the elongation to fracture, which should be attributed to segregation of B at the grain boundaries.

  10. Room-temperature synthesis of Zn(0.80)Cd(0.20)S solid solution with a high visible-light photocatalytic activity for hydrogen evolution.

    Science.gov (United States)

    Wang, Dong-Hong; Wang, Lei; Xu, An-Wu

    2012-03-21

    Visible light photocatalytic H(2) production from water splitting is of great significance for its potential applications in converting solar energy into chemical energy. In this study, a series of Zn(1-x)Cd(x)S solid solutions with a nanoporous structure were successfully synthesized via a facile template-free method at room temperature. The obtained solid solutions were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS) and N(2) adsorption-desorption analysis. The solid solutions show efficient photocatalytic activity for H(2) evolution from aqueous solutions containing sacrificial reagents S(2-) and SO(3)(2-) under visible-light irradiation without a Pt cocatalyst, and loading of the Pt cocatalyst further improves the visible-light photocatalytic activity. The optimal photocatalyst with x = 0.20 prepared at pH = 7.3 displays the highest activity for H(2) evolution. The bare and 0.25 wt% Pt loaded Zn(0.80)Cd(0.20)S nanoparticles exhibit a high H(2) evolution rate of 193 μmol h(-1) and 458 μmol h(-1) under visible-light irradiation (λ ≥ 420 nm), respectively. In addition, the bare and 0.25 wt% Pt loaded Zn(0.80)Cd(0.20)S catalysts show a high H(2) evolution rate of 252 and 640 μmol h(-1) under simulated solar light irradiation, respectively. Moreover, the Zn(0.80)Cd(0.20)S catalyst displays a high photocatalytic stability for H(2) evolution under long-term light irradiation. The incorporation of Cd in the solid solution leads to the visible light absorption, and the high content of Zn in the solid solution results in a relatively negative conduction band, a modulated band gap and a rather wide valence bandwidth, which are responsible for the excellent photocatalytic performance of H(2) production and for the high photostability

  11. Co{sub 3}O{sub 4}-Co{sub 2}ZnO{sub 4} spinels: The case for a solid solution

    Energy Technology Data Exchange (ETDEWEB)

    Perry, Nicola H. [Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States); Mason, Thomas O., E-mail: t-mason@northwestern.edu [Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States); Ma Chengcheng; Navrotsky, Alexandra [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States); Shi Yezhou; Bettinger, Joanna S.; Toney, Michael F. [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Paudel, Tula R.; Lany, Stephan [National Renewable Energy Laboratory, Golden, CO 80401 (United States); Zunger, Alex [University of Colorado, Boulder, CO 80309 (United States)

    2012-06-15

    In prior first-principles theoretical work we predicted a complete solid solution in the Co{sub 3}O{sub 4}-Co{sub 2}ZnO{sub 4} system, with a negligibly small mixing enthalpy. In this work we tested this prediction on bulk, large-grained specimens across the Co{sub 3}O{sub 4}-Co{sub 2}ZnO{sub 4} join, combining oxide melt solution calorimetry, differential scanning calorimetry, precise lattice parameter measurements, anomalous X-ray and neutron diffraction, and in situ electrical measurements. The calorimetric results confirm the presence of a solid solution at high temperatures, but with a large enthalpy of mixing that exceeds the predicted value. Because Co{sub 3}O{sub 4} and Co{sub 2}ZnO{sub 4} have essentially identical lattice parameters, this energetic destabilization must arise from factors other than the strain energy resulting from size mismatch. Changes in Co{sup 3+} spin states vs. temperature and zinc content are proposed to account for the positive excess enthalpy, and may also provide additional entropy to stabilize the solid solution at high temperature. - Graphical abstract: The first-principles theoretical prediction of a complete solid solution in Co{sub 3}O{sub 4}-Co{sub 2}ZnO{sub 4} spinels has been confirmed experimentally by calorimetric, structural, and electrical measurements. The large mixing enthalpy observed exceeds the predicted value and cannot be accounted for by strain or cation distribution contributions alone, since such effects are small in this system; instead, changes in the spin state of Co{sup 3+} are proposed to account for the mixing thermodynamics. Highlights: Black-Right-Pointing-Pointer Experiments confirm theory prediction of a solid solution in Co{sub 3}O{sub 4}-Co{sub 2}ZnO{sub 4} spinels. Black-Right-Pointing-Pointer Thermodynamics of mixing studied by calorimetric, electrical, structural methods. Black-Right-Pointing-Pointer Cation distributions found to be mostly normal for various compositions. Black

  12. Murine ameloblasts are immunonegative for Tcirg1, the v-H-ATPase subunit essential for the osteoclast plasma proton pump.

    Science.gov (United States)

    Bronckers, Antonius L J J; Lyaruu, Donacian M; Bervoets, Theodore J; Medina, Juan F; DenBesten, Pamela; Richter, Johan; Everts, Vincent

    2012-04-01

    Maturation stage ameloblasts of rodents express vacuolar type-H-ATPase in the ruffled border of their plasma membrane in contact with forming dental enamel, similar to osteoclasts that resorb bone. It has been proposed that in ameloblasts this v-H-ATPase acts as proton pump to acidify the enamel space, required to complete enamel mineralization. To examine whether this v-H-ATPase in mouse ameloblasts is a proton pump, we determined whether these cells express the lysosomal, T-cell, immune regulator 1 (Tcirg1, v-H-Atp6v(0)a(3)), which is an essential part of the plasma membrane proton pump that is present in osteoclasts. Mutation of this subunit in Tcirg1 null (or oc/oc) mice leads to severe osteopetrosis. No immunohistochemically detectable Tcirg1 was seen in mouse maturation stage ameloblasts. Strong positive staining in secretory and maturation stage ameloblasts however was found for another subunit of v-H-ATPase, subunit b, brain isoform (v-H-Atp6v(1)b(2)). Mouse osteoclasts and renal tubular epithelium stained strongly for both Tcirg1 and v-H-Atp6v(1)b(2). In Tcirg1 null mice osteoclasts and renal epithelium were negative for Tcirg1 but remained positive for v-H-Atp6v(1)b(2). The bone in these mutant mice was osteopetrotic, tooth eruption was inhibited or delayed, and teeth were often morphologically disfigured. However, enamel formation in these mutant mice was normal, ameloblasts structurally unaffected and the mineral content of enamel similar to that of wild type mice. We concluded that Tcirg1, which is essential for osteoclasts to pump protons into the bone, is not appreciably expressed in maturation stage mouse ameloblasts. Our data suggest that the reported v-H-ATPase in maturation stage ameloblasts is not the typical osteoclast-type plasma membrane associated proton pump which acidifies the extracellular space, but rather a v-H-ATPase potentially involved in intracellular acidification. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Mechanical alloying of Fe?Ni based nanostructured magnetic materials

    Science.gov (United States)

    Du, S. W.; Ramanujan, R. V.

    2005-04-01

    Alloys with the composition Fe 40Ni 38B 18Mo 4, Fe 49Ni 46Mo 5 and Fe 42Ni 40B 18 were processed from elemental powders by mechanical alloying and the microstructure was studied by differential scanning calorimetry (DSC), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. Nanocrystalline fcc solid solution was achieved as a result of mechanical alloying in all three alloy compositions and the grain size reduced to nanoscale but lattice strain was introduced. Molybdenum was found to affect the products of mechanical alloying, specifically, the Fe 3B phase formed in the Fe 42Ni 40B 18 alloy while no boride phase formed in the Fe 40Ni 38B 18Mo 4 alloy. SEM studies indicated that the presence of boron was found to make the milling process easier. Elemental mapping by SEM as well as XRD results showed that molybdenum does not dissolve easily in the Fe-Ni solid solution produced by milling. The DSC results suggested that an amorphous structure together with nanocrystals was obtained in the Fe 40Ni 38B 18Mo 4 and Fe 42Ni 40B 18 alloys. A two-stage crystallization process was found in the Fe 40Ni 38B 18Mo 4 and Fe 42Ni 40B 18 alloys, the presence of boron was found to make amorphization easier. TEM investigations were consistent with these XRD and DSC results. Heat-treated samples of the Fe 40Ni 38B 18Mo 4 and Fe 42Ni 40B 18 alloys milled for 100 h showed that molybdenum inhibited the grain growth. The saturation magnetization of the heat-treated Fe 40Ni 38B 18Mo 4 alloy milled for 100 h was stable, coercivity was reduced; on the other hand, the Ms of heat-treated Fe 42Ni 40B 18 alloy milled for 100 h decreased and the Hc increased. This difference in magnetic behavior is due to the alloying addition of molybdenum which affected the microstructural evolution during heat treatment, specifically by inhibition of the increase in grain size.

  14. Synthesis and electrical properties of the pyrochlore-type Gd2-yLayZr2O7 solid solution

    Directory of Open Access Journals (Sweden)

    León, C.

    2008-06-01

    Full Text Available Different compositions in the pyrochlore-type Gd2-yLayZr2O7 solid solution (0 ≤ y ≤ 1 were prepared at room-temperature by mechanically milling stoichiometric mixtures of the corresponding oxides. Irrespective of their lanthanum content, as-prepared powder samples consist of single-phase anion deficient fluorite materials, although long-range ordering of cations and anion vacancies characteristic of pyrochlores was observed in all cases after firing the samples at 1500°C. Interestingly, activation energy for oxygen migration in the series decreases as La-content increases, from 1.13 eV for Gd2Zr2O7 to 0.81 eV for GdLaZr2O7, whereas ionic conductivity was found to be almost La-content independent, at least for y ≤ 0.8 at T = 500°C and y ≤ 0.4 at T = 800°C. These results are explained in terms of weaker ion-ion interactions in better ordered structures (i.e., as La-content increases and highlight the importance of structural ordering/disordering in determining the dynamics of mobile oxygen ions.Partiendo de mezclas estequiométricas de los óxidos correspondientes, se prepararon por molienda mecánica y a temperatura ambiente diferentes composiciones en la solución sólida Gd2-yLayZr2O7 (0 ≤ y ≤ 1 con estructura de tipo pirocloro y conductora de iones oxígeno. Independientemente del contenido de lantano, los polvos extraídos del molino presentaron difractogramas similares al de una fluorita no estequiométrica aunque en todos los casos, el tratamiento térmico a 1500°C indujo la aparición del ordenamiento de largo alcance de cationes y vacancias aniónicas característico de pirocloros. La energía de activación para el proceso de migración de iones oxígeno en la serie disminuye a medida que se incrementa el contenido de lantano, desde 1.13 eV de Gd2Zr2O7 hasta 0.81 eV de GdLaZr2O7, mientras que la conductividad resultó ser prácticamente independiente del mismo hasta y ≤ 0.8 para T = 500°C e y ≤ 0.4 para T = 800

  15. Structural evolution of Ni-20Cr alloy during ball milling of elemental powders

    Energy Technology Data Exchange (ETDEWEB)

    Lopez B, I.; Trapaga M, L. G. [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Queretaro, Libramiento Norponiente No. 2000, Juriquilla, 76230 Queretaro (Mexico); Martinez F, E. [Centro de Investigacion e Innovacion Tecnologica, Cerrada de Cecati s/n, Col. Santa Catarina Azcapotzalco, 02250 Mexico D. F. (Mexico); Zoz, H., E-mail: israelbaez@gmail.co [Zoz GmbH, D-57482, Wenden (Germany)

    2011-07-01

    The ball milling (B M) of blended Ni and Cr elemental powders was carried out in a Simoloyer performing on high-energy scale mode at maximum production to obtain a nano structured Ni-20Cr alloy. The phase transformations and structural changes occurring during mechanical alloying were investigated by X-ray diffraction (XRD) and optical microscopy (Om). A gradual solid solubility of Cr and the subsequent formation of crystalline metastable solid solutions described in terms of the Avrami-Ero fe ev kinetics model were calculated. The XRD analysis of the structure indicates that cumulative lattice strain contributes to the driving force for solid solution between Ni and Cr during B M. Microstructure evolution has shown, additionally to the lamellar length refinement commonly observed, the folding of lamellae in the final processing stage. Om observations revealed that the lamellar spacing of Ni rich zones reaches a steady value near 500 nm and almost disappears after 30 h of milling. (Author)

  16. Formation and structure of V-Zr amorphous alloy thin films

    KAUST Repository

    King, Daniel J M

    2015-01-01

    Although the equilibrium phase diagram predicts that alloys in the central part of the V-Zr system should consist of V2Zr Laves phase with partial segregation of one element, it is known that under non-equilibrium conditions these materials can form amorphous structures. Here we examine the structures and stabilities of thin film V-Zr alloys deposited at room temperature by magnetron sputtering. The films were characterized by X-ray diffraction, transmission electron microscopy and computational methods. Atomic-scale modelling was used to investigate the enthalpies of formation of the various competing structures. The calculations confirmed that an amorphous solid solution would be significantly more stable than a random body-centred solid solution of the elements, in agreement with the experimental results. In addition, the modelling effort provided insight into the probable atomic configurations of the amorphous structures allowing predictions of the average distance to the first and second nearest neighbours in the system.

  17. Structural evolutions of the mechanically alloyed Al70Cu20Fe10 ...

    Indian Academy of Sciences (India)

    Mechanical alloying of the Al70Cu20Fe10 did not result in the formation of icosahedral quasicrystalline phase (i-phase) and a long time milling resulted in the formation of -Al(Cu,Fe) solid solution phase (-phase). The i-phase was observed only for short-time milled powders after heat treatment above 600°C. The ...

  18. Effect of particle size and microstructure on the hydrogen storage property in a V-Ti-Cr solid solution system

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Hanjung; Yoo, Jeong-Hyun; Roh, Ki-Min; Suh, Chang-Yul; Kim, Won-Baek [Mineral Resources Research Division, Korea Institute of Geoscience and Mineral Resources, 124 Gwahang-no, Yuseong-gu, Daejeon 305-350 (Korea, Republic of); Cho, Sung-Wook, E-mail: cho@kigam.re.kr [Mineral Resources Research Division, Korea Institute of Geoscience and Mineral Resources, 124 Gwahang-no, Yuseong-gu, Daejeon 305-350 (Korea, Republic of)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer V-Ti-Cr nano-particles were prepared via the electric explosion of wire. Black-Right-Pointing-Pointer Two kinds of particles with different size were formed. Black-Right-Pointing-Pointer Hydrogen storage capacity of nano-particles decreased due to increased surface area. Black-Right-Pointing-Pointer Plateau pressure was higher in the particle with smaller lattice parameter. Black-Right-Pointing-Pointer Hysteresis in P-C isotherm was larger in the particle with lower strain. - Abstract: Nano-particles of V-Ti and V-Ti-Cr alloys with a BCC (Body Centered Cubic) structure were prepared via the EEW (electric explosion of wire) method. However, due to the formation of chromium oxide (CrO{sub 0.87}) and/or vanadium oxide (V{sub 16}O{sub 3}) during the explosion, the exploded particles were deficient in Cr and V content, contrary to the anticipated composition, and micro-particles also formed in addition to the nano-particles. The hydrogen storage capacity of the exploded particles decreased compared to that of mechanically crushed particles from ingots, because the number of interstitial sites for hydrogen in the lattice was reduced due to the increased surface area and also because the BCC phase decreased as a result of the formation of oxide phases. As the lattice parameters of the alloys became small, the plateau pressure in the P-C isotherm increased because it was more difficult for hydrogen to diffuse through the lattice. It was also found that the strain induced by adding other elements in the V lattice reduced the hysteresis in the P-C isotherm.

  19. Triclinic-monoclinic-orthorhombic (T-M-O) structural transitions in phase diagram of FeVO4-CrVO4 solid solutions

    Science.gov (United States)

    Bera, Ganesh; Reddy, V. R.; Rambabu, P.; Mal, P.; Das, Pradip; Mohapatra, N.; Padmaja, G.; Turpu, G. R.

    2017-09-01

    Phase diagram of FeVO4-CrVO4 solid solutions pertinent with structural and magnetic phases is presented with unambiguous experimental evidences. Solid solutions Fe1-xCrxVO4 (0 ≤ x ≤ 1.0) were synthesized through the standard solid state route and studied by X-ray diffraction, scanning electron microscopy, energy dispersive spectra of X-rays, Raman spectroscopy, d.c. magnetization, and 57Fe Mössbauer spectroscopic studies. FeVO4 and CrVO4 were found to be in triclinic (P-1 space group) and orthorhombic structures (Cmcm space group), respectively. Cr incorporation into the FeVO4 lattice leads to the emergence of a new monoclinic phase dissimilar to the both end members of the solid solutions. In Fe1-xCrxVO4 up to x = 0.10, no discernible changes in the triclinic structure were found. A new structural monoclinic phase (C2/m space group) emerges within the triclinic phase at x = 0.125, and with the increase in Cr content, it gets stabilized with clear single phase signatures in the range of x = 0.175-0.25 as evidenced by the Rietveld analysis of the structures. Beyond x = 0.33, orthorhombic phase similar to CrVO4 (Cmcm space group) emerges and coexists with a monoclinic structure up to x = 0.85, which finally tends to stabilize in the range of x = 0.90-1.00. The Raman spectroscopic studies also confirm the structural transition. FeVO4 Raman spectra show the modes related to three nonequivalent V ions in the triclinic structure, where up to 42 Raman modes are observed in the present study. With the stabilization of structures having higher symmetry, the number of Raman modes decreases and the modes related to symmetry inequivalent sites collate into singular modes from the doublet structure. A systematic crossover from two magnetic transitions in FeVO4, at 21.5 K and 15.4 K to single magnetic transition in CrVO4, at 71 K (antiferromagnetic transition), is observed in magnetization studies. The intermediate solid solution with x = 0.15 shows two magnetic transitions

  20. Effect of hydrogen on the deformation development in titanium alloy of the Ti-Al-V system under creep

    Science.gov (United States)

    Grabovetskaya, G. P.; Zabudchenko, O. V.; Stepanova, E. N.; Mishin, I. P.

    2017-12-01

    In this work we investigate the deformation behavior of hydrogenated ultrafine-grained Ti-6Al-4V alloy under creep in the temperature range 723-873 K. The hydrogen presence in the amount of 0.26 wt % in a solid solution is found to lead to a decrease in the rate of steady-state creep and strain to failure and increase in time to failure of Ti-6Al-4V alloy. Possible reasons of a rise in the creep rate and strain to failure of the alloy under creep and simultaneous hydrogen degassing are discussed.

  1. Study of the Structure and Hardness of Alloys of the Sn - Cu - Co System Used as Diamond Abrasive Tool Binders

    Science.gov (United States)

    Sokolov, E. G.; Artem'ev, V. P.; Voronova, M. I.

    2017-09-01

    The effect of the chemical composition of alloys of the Sn - Cu - Co system used as a binder for diamond abrasive tools on their structure and hardness is studied. It is shown that in the range of concentrations of the elements studied alloy structure is represented by three phases, i.e., β-Co, a solid solution of tin and cobalt in copper (Cu), and an ɛ (Cu3Sn) intermetallic phase. The lowest microhardness of the three phases is exhibited by β-Co, as a result of which with an increase in cobalt content alloy macrohardness decreases.

  2. Structural, vibrational and photoluminescence properties of Sr{sub (1-x)}Pb{sub x}MoO{sub 4} solid solution synthesized by solid state reaction

    Energy Technology Data Exchange (ETDEWEB)

    Hallaoui, A.; Taoufyq, A. [IM2NP, UMR CNRS 7334, University of Toulon, BP20132, 83957 La Garde (France); LME, Faculty of Sciences, University Ibn Zohr, 80000 Agadir (Morocco); Arab, M. [IM2NP, UMR CNRS 7334, University of Toulon, BP20132, 83957 La Garde (France); Bakiz, B.; Benlhachemi, A.; Bazzi, L. [LME, Faculty of Sciences, University Ibn Zohr, 80000 Agadir (Morocco); Valmalette, J-C.; Villain, S.; Guinneton, F. [IM2NP, UMR CNRS 7334, University of Toulon, BP20132, 83957 La Garde (France); Gavarri, J-R., E-mail: gavarri.jr@univ-tln.fr [IM2NP, UMR CNRS 7334, University of Toulon, BP20132, 83957 La Garde (France)

    2016-07-15

    Highlights: • The solid solution Sr{sub (1-x)}Pb{sub (x)}MoO{sub 4} is characterized by X-ray diffraction. • Raman spectroscopy confirm that the solid solution is disordered. • Photoluminescence experiments are carried out under X-ray excitation. • Emission bands can be decomposed into four components between 2.1 and 2.9 eV. • The intensities of emission bands reach a maximum for 0.1 < x < 0.4. - Abstract: In this paper, strontium lead molybdate Sr{sub 1-x}Pb{sub x}MoO{sub 4} polycrystalline samples with 0 ≤ x ≤ 1 were prepared by solid state preparation method at 1000 °C. These materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and micro-Raman spectroscopy. Their photoluminescence responses were analyzed under X-ray excitation. Rietveld refinements indicate that all the materials present a scheelite-type tetragonal structure. Micro-Raman spectra confirmed the formation of the solid solution with a specific effect due to Sr-O-Mo and Pb-O-Mo links in the scheelite structure. SEM images showed modifications in the shapes and grain sizes as x increased. Broad photoluminescent emission bands were observed in the energy range 2.1–2.9 eV. The emission bands were decomposed into four gaussian components. The intensities of all components presented a strong maximum in the composition range 0.1 < x < 0.4.

  3. Ultrasonic semi-solid coating soldering 6061 aluminum alloys with Sn-Pb-Zn alloys.

    Science.gov (United States)

    Yu, Xin-ye; Xing, Wen-qing; Ding, Min

    2016-07-01

    In this paper, 6061 aluminum alloys were soldered without a flux by the ultrasonic semi-solid coating soldering at a low temperature. According to the analyses, it could be obtained that the following results. The effect of ultrasound on the coating which promoted processes of metallurgical reaction between the components of the solder and 6061 aluminum alloys due to the thermal effect. Al2Zn3 was obtained near the interface. When the solder was in semi-solid state, the connection was completed. Ultimately, the interlayer mainly composed of three kinds of microstructure zones: α-Pb solid solution phases, β-Sn phases and Sn-Pb eutectic phases. The strength of the joints was improved significantly with the minimum shear strength approaching 101MPa. Copyright © 2016. Published by Elsevier B.V.

  4. Relationship between silver concentration with microstructural and mechanical properties of rolled AlZn alloy

    Energy Technology Data Exchange (ETDEWEB)

    Valdez, S., E-mail: svaldez@fis.unam.mx [Instituto de Ciencias Fisicas-Universidad Nacional Autonoma de Mexico, Av. Universidad S/N, Col. Chamilpa, 062210 Cuernavaca, Morelos (Mexico); Perez, R.; Rodriguez-Diaz, R.A. [Instituto de Ciencias Fisicas-Universidad Nacional Autonoma de Mexico, Av. Universidad S/N, Col. Chamilpa, 062210 Cuernavaca, Morelos (Mexico); Angeles-Chavez, C. [Instituto Mexicano del Petroleo, Eje central Lazaro Cardenas 152, Mexico D.F. 07730 (Mexico); Casolco, S.R. [Instituto Tecnologico y de Estudios Superiores de Monterrey, Campus Puebla, Via Atlixcayotl 2301. Puebla, Pue. 2800 (Mexico)

    2010-05-25

    The relationship of Ag addition on microstructural and mechanical properties of rolled AlZn alloy was investigated. AlZn alloys were prepared by metal mould casting method and the Ag addition was done by Vortex technique. Microstructural characterization of AlZnAg specimens was analyzed by means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Results show that the phases of the as-cast state alloy are solid solution zinc-rich hexagonal close-packed (hcp) crystal structure, named {eta}-phase and {alpha}-Al solid solution with Zn dissolved into the matrix. The silver concentration in AlZn alloy influences the volume of AgZn{sub 3} precipitates. The mechanical properties, especially the flow stress and elongation of the alloy were improved by the Ag addition. The Vortex method was used in order to diminish the process cost, generating an alloy with homogenous microstructure, less casting porosity and better mechanical properties.

  5. Synthesis of the metastable α-Al1.8Fe0.2O3 solid solution from precursors prepared by combustion

    OpenAIRE

    Cordier, Anne; Peigney, Alain; De Grave, Eddy; Flahaut, Emmanuel; Laurent, Christophe

    2006-01-01

    The aim of the paper is to synthesise α-Al1.8Fe0.2O3 solid solutions from precursors prepared by the nitrate/fuel combustion synthesis route, using either citric acid or urea, or a mixture of both as the fuel, and different fuel/nitrates ratios. In a first part, global reactions are proposed for each synthesis, which are useful to explain the differences in powder volume, morphology, crystallisation state and specific surface area reported in the second part of the study. In a third part, the...

  6. Long-time Luminescence Kinetics of Localized excitons and conduction Band Edges Smearing in ZnSe(1-c)Tec Solid Solutions

    DEFF Research Database (Denmark)

    Klochikhin, O.; Ogloblin, S. G.; Permogorov, S.

    2000-01-01

    It is shown that the integrated luminescence intensity of localized excitons in solid solutions ZnSe(1 - c)Tec has a component slowly decaying with time. After the excitation above the mobility threshold, the long-time intensity decreases exponentially, with a fractional exponent changing from a ...... a value corresponding to the critical index of anomalous diffusion to the index of normal diffusion as the temperature increases from 5 to 80 K. This change allows estimation of the energy scale for the fluctuation tail of the conduction band. (C) 2000 MAIK "Nauka / Interperiodica"....

  7. Tetragonal-cubic phase boundary in nanocrystalline ZrO{sub 2}-Y{sub 2}O{sub 3} solid solutions synthesized by gel-combustion

    Energy Technology Data Exchange (ETDEWEB)

    Fabregas, Ismael O. [CINSO (Centro de Investigaciones en Solidos), CITEFA-CONICET, J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Craievich, Aldo F.; Fantini, Marcia C.A. [Instituto de Fisica, Universidade de Sao Paulo, Travessa R da Rua do Matao, No. 187, Cidade Universitaria, 05508-900 Sao Paulo (Brazil); Millen, Ricardo P.; Temperini, Marcia L.A. [Instituto de Quimica, Universidade de Sao Paulo, Avenida Prof. Lineu Prestes 748, Cidade Universitaria, 05508-900 Sao Paulo (Brazil); Lamas, Diego G., E-mail: dlamas@uncoma.edu.ar [CINSO (Centro de Investigaciones en Solidos), CITEFA-CONICET, J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Laboratorio de Caracterizacion de Materiales, Facultad de Ingenieria, Universidad Nacional del Comahue, Buenos Aires 1400, (8300) Neuquen Capital, Prov. de Neuquen (Argentina)

    2011-04-21

    Research highlights: > Gel-combustion synthesis yields compositionally homogeneous, single-phased ZrO{sub 2}-Y{sub 2}O{sub 3} nanopowders, that exhibit the presence at room temperature of three different phases depending on Y{sub 2}O{sub 3} content, namely two tetragonal forms (t' and t'') and the cubic phase. > Phase identification can be achieved by synchrotron XPD (SXPD) and Raman spectroscopy since the tetragonal forms and the cubic phase can be distinguished by these techniques. > The crystallographic features of ZrO{sub 2}-Y{sub 2}O{sub 3} nanopowders were determined by SXPD. They are similar to those reported by Yashima and coworkers for compositionally homogeneous materials containing larger (micro)crystals. However, the lattice parameters are slightly different and the axial ratios c/a of our t' samples are smaller than those reported by these authors. > Compositional t'/t'' and t''/cubic phase boundaries are located at (9 {+-} 1) and (10.5 {+-} 0.5) mol% Y{sub 2}O{sub 3}, respectively. > For the whole series of nanocrystalline ZrO{sub 2}-Y{sub 2}O{sub 3} solid solutions studied in the present work, no evidences of the presence of a mixture of phases - as reported by Yashima and coworkers for microcrystalline solid solutions - were detected. - Abstract: By means of synchrotron X-ray powder diffraction (SXPD) and Raman spectroscopy, we have detected, in a series of nanocrystalline and compositionally homogeneous ZrO{sub 2}-Y{sub 2}O{sub 3} solid solutions, the presence at room temperature of three different phases depending on Y{sub 2}O{sub 3} content, namely two tetragonal forms and the cubic phase. The studied materials, with average crystallite sizes within the range 7-10 nm, were synthesized by a nitrate-citrate gel-combustion process. The crystal structure of these phases was also investigated by SXPD. The results presented here indicate that the studied nanocrystalline ZrO{sub 2}-Y{sub 2}O{sub 3} solid

  8. Synthesis and characterization of Sr{sub 2}Ir{sub 1-x}M{sub x}O{sub 4} (M=Ti, Fe, Co) solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Gatimu, Alvin J.; Berthelot, Romain; Muir, Sean; Sleight, Arthur W. [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States); Subramanian, M.A., E-mail: mas.subramanian@oregonstate.edu [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States)

    2012-06-15

    The effects of Ti, Fe and Co substitutions for Ir on the structure and on the physical properties of Sr{sub 2}IrO{sub 4} are investigated. A complete solid solution Sr{sub 2}Ir{sub 1-x}Ti{sub x}O{sub 4} is obtained while both Fe and Co doping are relatively limited. In each case however, the c-axis cell parameter and the initial IrO{sub 6} octahedra tilting decreases with substitution. Doping with Ti, Fe and Co results in a decrease of the magnetic susceptibility and in an increase in the paramagnetic effective moment for Co and Fe doped samples and a suppression of the weak ferromagnetic ordering observed for Sr{sub 2}IrO{sub 4}. - Graphical abstract: Solid solutions of Sr{sub 2}Ir{sub 1-x}M{sub x}O{sub 4} (M=Ti, Fe, Co) have been synthesized and characterized by powder X-ray diffraction, magnetism and electrical measurements. Changes in the a parameter and decreases in both the c-axis cell parameters and the initial IrO{sub 6} octahedra tilting are found to be correlated. Highlights: Black-Right-Pointing-Pointer Solid Solutions of Sr{sub 2}Ir{sub 1-x}M{sub x}O{sub 4} (M=Ti, Fe, Co) are synthesized. Black-Right-Pointing-Pointer The Sr{sub 2}Ir{sub 1-x}Ti{sub x}O{sub 4} solid solution is complete while those of Fe and Co are relatively limited. Black-Right-Pointing-Pointer The change in a cell parameter with substitution is much less than that of the c parameter. Black-Right-Pointing-Pointer Decreased tilting and the smaller size of the M cation contrastingly affect the a parameter. Black-Right-Pointing-Pointer Doping results in a suppression of the weak ferromagnetic ordering in Sr{sub 2}IrO{sub 4}.

  9. Strong work-hardening behavior induced by the solid solution strengthening of dendrites in TiZr-based bulk metallic glass matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Ma, D.Q. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Jiao, W.T. [College of Education, Hebei Normal University of Science and Technology, Qinhuangdao 066004 (China); Zhang, Y.F. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Hebei Vocational and Technical College of Building Materials, Qinhuangdao 066004 (China); Wang, B.A.; Li, J.; Zhang, X.Y. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Ma, M.Z., E-mail: mz550509@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Liu, R.P. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China)

    2015-03-05

    Highlights: • Hardness of dendrite of TiZr-based BMGMCs increases. • Strong work-hardening behavior is obtained after solid solution strengthening. • Lattice distortions of dendrite suffering from rapid cooling are detected. - Abstract: A series of TiZr-based bulk metallic glass matrix composites (BMGMCs) with distinguished mechanical properties are successfully fabricated by adding different volume fractions of Ta (Ti{sub 38.8}Zr{sub 28.8}Cu{sub 6.2}Be{sub 16.2}Nb{sub 10} as the basic composition, denoted as Ta{sub 0.0}–Ta{sub 8.0}). Along with the growth of precipitated phase, typical dendritic morphology is fully developed in the TiZr-based BMGMCs of Ta{sub 8.0}. Energy-dispersive spectrometry analysis of the dendrites and glass matrix indicates that the metallic elements of Nb and Ta should preferentially form solid solution into dendrites. The chaotic structure of high-temperature precipitate phase is trapped down by the rapid cooling of the copper-mould. The detected lattice distortions in the dendrites are attributed to the strong solid solution strengthening of the metallic elements of Ti, Zr, Nb, and Ta. These lattice distortions increase the resistance of the dislocation motion and pin the dislocations, thus the strength and hardness of dendrite increase. Dendrites create a strong barrier for the shear band propagation and generate multiple shear bands after solid solution strengthening, thereby providing the TiZr-based BMGMCs with greatly improved capacity to sustain plastic deformation and resistance to brittle fracture. Thus, the TiZr-based BMGMCs possess distinguished work-hardening capability. Among these TiZr-based BMGMCs, the sample Ta{sub 0.5} possesses the largest plastic strain (ε{sub p}) at 20.3% and ultimate strength (σ{sub max}) of 2613 MPa during compressive loading. In addition, the sample of Ta{sub 0.5} exhibits work-hardening up to an ultrahigh tensile strength of 1680 MPa during the tensile process, and then progressively

  10. Corrosion-Resistant High-Entropy Alloys: A Review

    Directory of Open Access Journals (Sweden)

    Yunzhu Shi

    2017-02-01

    Full Text Available Corrosion destroys more than three percent of the world’s gross domestic product. Therefore, the design of highly corrosion-resistant materials is urgently needed. By breaking the classical alloy-design philosophy, high-entropy alloys (HEAs possess unique microstructures, which are solid solutions with random arrangements of multiple elements. The particular locally-disordered chemical environment is expected to lead to unique corrosion-resistant properties. In this review, the studies of the corrosion-resistant HEAs during the last decade are summarized. The corrosion-resistant properties of HEAs in various aqueous environments and the corrosion behavior of HEA coatings are presented. The effects of environments, alloying elements, and processing methods on the corrosion resistance are analyzed in detail. Furthermore, the possible directions of future work regarding the corrosion behavior of HEAs are suggested.

  11. Effect of deposition current on microstructure and properties of CoCrWC alloy PTA coatings

    Directory of Open Access Journals (Sweden)

    R. M. G. Paes

    2014-09-01

    Full Text Available Cobalt-Based alloys are largely applied to the surface of components as welded coatings. Carbides reinforced CoCrWC system is used to extend the service life under harsh environments involving wear and corrosion in different media. This work aims to evaluate the effect of deposition current on the microstructure and properties of PTA coatings. So, CoCrWC alloy (Stellite #6 was processed on AISI316L stainless steel plates with the following main arc current: 100, 120, 150, 180 and 200A. So, different interaction with the substrate must be expected and its effect on coatings features was evaluated. The geometry of single track coatings, dilution, formed phases and phase volume fraction was assessed by laser Confocal, scanning electron microscopy and X-ray diffraction analysis. Vickers hardness and wear tests were carried out to correlate microstructure to properties of coatings. Coatings showed microstructure composed by hypoeutectic dendrites of Cobalt solid solution and interdendrictic carbides. Dilution increased with deposition current from 11,8 e 56,5% which reduced the carbides fraction and increased the Cobalt solid solution areas, resulting in hardness decrease from 500 to 310HV0,5. Higher deposition current induced mass loss rate increase on pin-on-disc sliding wear tests, arising 44,38% increment on wear coefficient, as a consequence of the lower carbides fraction and solid solution alloying and refinement degree of the microstructure.

  12. Two main and a new type rare earth elements in Mg alloys: A review

    Science.gov (United States)

    Kong, Linghang

    2017-09-01

    Magnesium (Mg) alloys stand for the lightest structure engineering materials. Moreover, the strengthening of Mg alloys in ductility, toughness and corrosion predominates their wide applications. With adding rare earth elements in Mg, the mechanical properties will be improved remarkably, especially their plasticity and strength. A brief overview of the addition of rare earth elements for Mg alloys is shown. The basic mechanisms of strengthening Mg alloys with rare earth elements are reviewed, including the solid solution strengthening, grain refinement and long period stacking ordered (LPSO) phase. Furthermore, the available rare earth elements are summarized by type, chemical or physical effects and other unique properties. Finally, some challenge problems that the research is facing and future expectations of ra-re-earth Mg alloys are stated and discussed.

  13. Strengthening mechanisms of indirect-extruded Mg–Sn based alloys at room temperature

    Directory of Open Access Journals (Sweden)

    Wei Li Cheng

    2014-12-01

    Full Text Available The strength of a material is dependent on how dislocations in its crystal lattice can be easily propagated. These dislocations create stress fields within the material depending on their intrinsic character. Generally, the following strengthening mechanisms are relevant in wrought magnesium materials tested at room temperature: fine-grain strengthening, precipitate strengthening and solid solution strengthening as well as texture strengthening. The indirect-extruded Mg–8Sn (T8 and Mg–8Sn–1Al–1Zn (TAZ811 alloys present superior tensile properties compared to the commercial AZ31 alloy extruded in the same condition. The contributions to the strengthen of Mg–Sn based alloys made by four strengthening mechanisms were calculated quantitatively based on the microstructure characteristics, physical characteristics, thermomechanical analysis and interactions of alloying elements using AZ31 alloy as benchmark.

  14. Role of the chemical substitution on the luminescence properties of solid solutions Ca{sub (1−x)}Cd{sub (x)}WO{sub 4} (0 ≤ x ≤1)

    Energy Technology Data Exchange (ETDEWEB)

    Taoufyq, A. [Institut Matériaux Microélectronique et Nanosciences de Provence, Aix Marseille Université, CNRS, Université de Toulon, IM2NP UMR 7334, 83957 La Garde (France); Laboratoire Matériaux et Environnement LME, Faculté des Sciences, Université Ibn Zohr, BP 8106, Cité Dakhla, Agadir (Morocco); CEA, DEN, Département d' Etudes des Réacteurs, Service de Physique Expérimentale, Laboratoire Dosimétrie Capteurs Instrumentation, 13108 Saint-Paul-lez-Durance (France); Mauroy, V.; Guinneton, F. [Institut Matériaux Microélectronique et Nanosciences de Provence, Aix Marseille Université, CNRS, Université de Toulon, IM2NP UMR 7334, 83957 La Garde (France); Bakiz, B. [Laboratoire Matériaux et Environnement LME, Faculté des Sciences, Université Ibn Zohr, BP 8106, Cité Dakhla, Agadir (Morocco); Villain, S. [Institut Matériaux Microélectronique et Nanosciences de Provence, Aix Marseille Université, CNRS, Université de Toulon, IM2NP UMR 7334, 83957 La Garde (France); and others

    2015-10-15

    Highlights: • Luminescence can be modified by chemical substitution in solid solutions Ca{sub 1−x}Cd{sub x}WO{sub 4}. • The various emission spectra (charge transfer) were obtained under X-ray excitation. • Scheelite or wolframite solid solutions presented two types of emission spectra. • A luminescence component depended on cadmium substitution in each solid solution. • A component was only characteristic of oxyanion symmetry in each solid solution. - Abstract: We have investigated the chemical substitution effects on the luminescence properties under X-ray excitation of the solid solutions Ca{sub (1−x)}Cd{sub (x)}WO{sub 4} with 0 ≤ x ≤ 1. Two types of wide spectral bands, associated with scheelite-type or wolframite-type solid solutions, have been observed at room temperature. We decomposed each spectral band into several spectral components characterized by energies and intensities varying with composition x. One Gaussian component was characterized by an energy decreasing regularly with the composition x, while the other Gaussian component was only related to the tetrahedral or octahedral configurations of tungstate groups WO{sub 4}{sup 2−} or WO{sub 6}{sup 6−}. The luminescence intensities exhibited minimum values in the composition range x < 0.5 corresponding to scheelite-type structures, then, they regularly increased for cadmium compositions x > 0.5 corresponding to wolframite-type structures.

  15. Effect of nano/micro-Ag compound particles on the bio-corrosion, antibacterial properties and cell biocompatibility of Ti-Ag alloys.

    Science.gov (United States)

    Chen, Mian; Yang, Lei; Zhang, Lan; Han, Yong; Lu, Zheng; Qin, Gaowu; Zhang, Erlin

    2017-06-01

    In this research, Ti-Ag alloys were prepared by powder metallurgy, casting and heat treatment method in order to investigate the effect of Ag compound particles on the bio-corrosion, the antibacterial property and the cell biocompatibility. Ti-Ag alloys with different sizes of Ag or Ag-compounds particles were successfully prepared: small amount of submicro-scale (100nm) Ti 2 Ag precipitates with solid solution state of Ag, large amount of nano-scale (20-30nm) Ti 2 Ag precipitates with small amount of solid solution state of Ag and micro-scale lamellar Ti 2 Ag phases, and complete solid solution state of Ag. The mechanical tests indicated that both nano/micro-scale Ti 2 Ag phases had a strong dispersion strengthening ability and Ag had a high solid solution strengthening ability. Electrochemical results shown the Ag content and the size of Ag particles had a limited influence on the bio-corrosion resistance although nano-scale Ti 2 Ag precipitates slightly improved corrosion resistance. It was demonstrated that the nano Ag compounds precipitates have a significant influence on the antibacterial properties of Ti-Ag alloys but no effect on the cell biocompatibility. It was thought that both Ag ions release and Ti 2 Ag precipitates contributed to the antibacterial ability, in which nano-scale and homogeneously distributed Ti 2 Ag phases would play a key role in antibacterial process. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Evaluation of Surface Mechanical Properties and Grindability of Binary Ti Alloys Containing 5 wt % Al, Cr, Sn, and V

    Directory of Open Access Journals (Sweden)

    Hae-Soon Lim

    2017-11-01

    Full Text Available This study aimed to investigate the relationship between the surface mechanical properties and the grindability of Ti alloys. Binary Ti alloys containing 5 wt % concentrations of Al, Cr, Sn, or V were prepared using a vacuum arc melting furnace, and their surface properties and grindability were compared to those of commercially pure Ti (cp-Ti. Ti alloys containing Al and Sn had microstructures that consisted of only α phase, while Ti alloys containing Cr and V had lamellar microstructures that consisted of α + β phases. The Vickers microhardness of Ti alloys was increased compared to those of cp-Ti by the solid solution strengthening effect. Among Ti alloys, Ti alloy containing Al had the highest Vickers microhardness. At a low SiC wheel speed of 5000 rpm, the grinding rates of Ti alloys showed an increasing tendency as the hardness values of Ti alloys decreased. At a high SiC wheel speed of 10,000 rpm, the grinding rates of Ti alloys showed an increasing tendency as the tensile strength values increased. The Ti alloy containing Al, which showed the lowest tensile strength, had the lowest grinding rate. The grinding ratios of the Ti alloys were higher than those of cp-Ti at both wheel revolution speeds of 5000 and 10,000 rpm. The grinding ratio of the Ti alloy containing Al was significantly increased at 10,000 rpm (p < 0.05.

  17. Solid state amorphisation in binary systems prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, G., E-mail: gemagonz@ivic.v [Lab. Ciencia e Ing. de Materiales, Instituto Venezolano de Investigaciones Cientificas, IVIC, Caracas (Venezuela, Bolivarian Republic of); Sagarzazu, A. [Lab. Ciencia e Ing. de Materiales, Instituto Venezolano de Investigaciones Cientificas, IVIC, Caracas (Venezuela, Bolivarian Republic of); Bonyuet, D. [Instituto de Investigacion en Biomedicina y Ciencias Aplicadas, Universidad de Oriente, Cumana (Venezuela, Bolivarian Republic of); D' Angelo, L. [UNEXPO, Universidad Experimental Politecnica Luis Caballero Mejias, Dpto. Ing. Mecanica (Venezuela, Bolivarian Republic of); Villalba, R. [Lab. Ciencia e Ing. de Materiales, Instituto Venezolano de Investigaciones Cientificas, IVIC, Caracas (Venezuela, Bolivarian Republic of)

    2009-08-26

    In the present work a detailed study of amorphisation in different systems prepared by mechanical alloying under the same experimental conditions was carried out, milling up to 50 and 100 h in some cases. The systems studied were: AlTi, AlNi, AlFe, FeNi, FeCo, NiMo, NiW, NiCo, MoW, CoMo. These systems were chosen to study the effect of Al-transition metal, transition metal-transition metal and also systems with large and small negative heat of mixing, different and similar crystal structures, atomic sizes and diffusion coefficients. Calculations based on the Miedema model for alloy formation and amorphisation on all the alloys studied were performed. The experimental results from X-ray diffraction and transmission electron microscopy showed that the systems based on Fe (FeNi, FeCo and FeAl) did not amorphised, even after milling for 100 h, and formed a stable solid solution with a nanometric grain size of 7 nm. The systems NiMo, NiW, MoW and CoMo (systems with small negative heat of mixing), showed amorphisation after 50 h of milling. NiAl and TiAl form an intermediate amorphous phase after around 20 h of milling and with further milling they recrystallize into a fcc solid solution. Agreement between the theoretical calculations based on the Miedema model and the experimental results was found in most of the systems.

  18. Zirconium-cerin solid solutions: thermodynamic model and thermal stability at high temperature; Solutions solides de zirconium dans la cerine: modele thermodynamique et stabilite thermique a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Janvier, C.

    1998-04-02

    The oxides-gaseous dioxygen equilibria and the textural thermal stability of six zirconium-cerin solutions Ce{sub 1-x}Zr{sub x}O{sub 2} (0solid solutions and the gaseous oxygen by thermal gravimetric analysis at 600 degrees Celsius has shown that these solutions have not a ideal behaviour. A thermodynamic model where the point defects of solutions are included describe them the best. It becomes then possible to know the variations of the concentrations of the point defects in terms of temperature, oxygen pressure and zirconium concentration. A kinetic study (by calcination at 950 degrees Celsius of the solid solutions) of the specific surface area decrease has revealed a minima (0

  19. Oxalate coprecipitation synthesis and transport properties of polycrystalline Sr{sub 1-x}La{sub x}PbO{sub 3-{delta}} solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Drozd, Vadim A.; Gabovich, Alexander M.; Pekala, Marek; Nedilko, Sergey A.; Gierlowski, Piotr

    2004-03-24

    Solid solutions Sr{sub 1-x}La{sub x}PbO{sub 3-{delta}} with x=0, 0.05, 0.1, 0.15, 0.2 and 0.25 were synthesized by oxalate precursor coprecipitation methods. The solid solutions obtained were analyzed by the XRD technique and iodometric titration. Resistivity {rho} and thermoelectric power S were measured for temperatures 20 K

  20. Relative Stability of FE and AFE States in (Na0,5Bi0,5) TiO3-based Solid Solutions

    Science.gov (United States)

    Sobolev, V. L.; Ishchuk, V. M.; Gusakova, L. G.; Kisel, N. G.; Kuzenko, D. V.; Spiridonov, N. A.

    2015-03-01

    Changes of the relative stability of antiferroelectric (AFE) and ferroelectric (FE) phases in the [(Na0.5Bi0.5)0.80 Ba0.20](Ti1-yBy) O3 system of solid solutions with the B-site ion substitutions have been studied. Ions of zirconium and tin along some ions complexes such as (InNb), (FeNb) and several others were used for substitutions. The increase in the substituent ion content leads to nearly linear variation of the crystal cell size along with changes of the relative stability of the AFE and FE phases according to the tolerance factor variation. Substituent ions with ionic radii larger than the ionic radius of original ion evoke a decrease of the FE-AFE phase transition temperature. The substituent ions with smaller ionic radii have the opposite effect. Our results demonstrate that the size of the substituent ion causes a predominant influence on the relative stability of the FE and AFE states in (Na0.5Bi0.5) TiO3-based solid solutions. Our studies also indicate the way to raise the FE-AFE phase transition temperature.

  1. The effect of Mn substitution on the structure and magnetic properties of Se(Cu{sub 1-x}Mn{sub x})O{sub 3} solid solution

    Energy Technology Data Exchange (ETDEWEB)

    Escamilla, R [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, 04510 Mexico DF (Mexico); Duran, A [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, 04510 Mexico DF (Mexico); Rosales, M I [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, 04510 Mexico DF (Mexico); Moran, E [Laboratorio Complutense de Altas Presiones and Departamento de Quimica Inorganica, Facultad de Ciencias Quimicas, Universidad Complutense, 28040-Madrid (Spain); Alario-Franco, M A [Laboratorio Complutense de Altas Presiones and Departamento de Quimica Inorganica, Facultad de Ciencias Quimicas, Universidad Complutense, 28040-Madrid (Spain)

    2003-04-02

    The effects of Mn substitution on the structure and magnetic properties of the SeMO{sub 3} (M = Cu{sub 1-x}Mn{sub x}) solid solution have been studied. Rietveld refinements of the x-ray diffraction patterns of these samples indicate that the manganese ions occupy copper sites. This replacement induces significant changes in the M-O bond lengths that give rise to abrupt decreases of the [M-O{sub 6}] octahedral distortion. In contrast, the M-O(1)-M and M-O(2)-M bond angles remain essentially constant. The magnetic behaviour of this solid solution was studied in the temperature range of 2 K < T < 300 K. The temperature dependence of the inverse magnetic susceptibility is well described by the Curie-Weiss law at high temperatures, in the composition range studied. We found that the substitution of Mn for Cu induces a sharp drop in the saturation moment of SeCuO{sub 3}. At about 10% of Mn there is a change from positive to negative Weiss constant {theta}{sub W} that is mainly due to the [M-O{sub 6}] octahedral distortion introduced by the substitution of the larger Mn ions in the structure. The M- H isotherms show a weak ferromagnetism at about 52 K in SeMnO{sub 3}.

  2. Combined major and trace element LA-ICP-MS analysis of compositional variations in simple solid solutions through cross correlation with an EPMA-characterized working standard.

    Science.gov (United States)

    Zellmer, Georg F; Dulski, Peter; Iizuka, Yoshiyuki

    2012-08-01

    Determining correlated major and trace element zoning profiles is an important goal in modern microanalysis and is critical to some geospeedometric applications. We show that a precise determination of relative variations in major element compositions of simple solid solutions is possible by LA-ICPMS, and that low accuracy (analytical bias) can be corrected for through cross correlation with electron problem microanalyzer (EPMA)-characterized working standards. Further, the relative uncertainties on binary or quasibinary solid solution endmember proportions are always lower than the relative uncertainties on the ratio of the principle substituting elements by at least a factor of 2. In calcic plagioclase, for example, the relative uncertainty on X(An) is a factor of (1-X(An)) smaller than the relative uncertainty on Ca/Na. Using a well-characterized, concentrically zoned bytownite crystal as an example, we compare reproducibilities of FE-EPMA and W-EPMA analyses with 2 μm beam diameter and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) with 16 μm beam diameter. While the accuracy of LA-ICP-MS analyses is low (analytical bias), the precision of LA-ICP-MS analyses is slightly higher than that of FE-EPMA data and comparable to that of the W-EPMA data. EPMA-corrected LA-ICP-MS data can thus be used to characterize major oxide compositional variations and potential covariations with trace elements within individual crystals.

  3. Synthesis of coffinite, USiO4, and structural investigations of UxTh(1-x)SiO4 solid solutions.

    Science.gov (United States)

    Labs, Sabrina; Hennig, Christoph; Weiss, Stephan; Curtius, Hilde; Zänker, Harald; Bosbach, Dirk

    2014-01-01

    The miscibility behavior of the USiO4-ThSiO4 system was investigated. The end members and 10 solid solutions UxTh(1-x)SiO4 with x = 0.12-0.92 were successfully synthesized, without formation of other secondary uranium or thorium phases. Lattice parameters of the solid solutions evidently follow Vegard's Law. Investigation of the local structure with EXAFS reveals small differences between the U and Th environment attributed to different atomic radii of the metal atoms but no implications for a miscibility gap. The data provided confirm complete miscibility for the system USiO4-ThSiO4. The structure of the end members was studied in detail with XRD and discussed with special regard to the oxygen positions and the often neglected Si-O bond length. USiO4 could be obtained without UO2 impurities and the lattice parameters derived from Rietveld refinement as c = 6.2606(3) Å and a = 6.9841(3) Å. The Si-O distance in USiO4 appears to be 1.64 Å, which is more reasonable than earlier reported values.

  4. Photocatalytic H2 production from spinels ZnGa2-xCrxO4 (0≤x≤2) solid solutions

    Science.gov (United States)

    Xu, Xiaoxiang; Xie, Yinghao; Ni, Shuang; Azad, Abul K.; Cao, Tongcheng

    2015-10-01

    Solid solutions of ZnGa2-xCrxO4 (0≤x≤2) were successfully prepared by solid state reactions. Introducing Cr into ZnGa2O4 crystal structure significantly improves its light absorption and greatly enhances its photocatalytic activity. An optimized Cr content (x=1.5 for ZnGa0.5Cr1.5O4) was found for the solid solutions with the highest photocatalytic hydrogen production rate (~775 μmol/h). Compositional analysis suggests there is a strong enrichment of Cr at the surface of sample ZnGa0.5Cr1.5O4 compared with other samples. Theoretical calculations suggest their electronic structures involve spin-polarized conduction band (CB) and valence band (VB) that are mainly composed of Cr 3d orbitals. The highest photocatalytic activity observed in ZnGa0.5Cr1.5O4 is probably due to the higher Cr content at the surface that favors the Cr 3d orbital overlapping.

  5. In situ characterization of uranium and americium oxide solid solution formation for CRMP process: first combination of in situ XRD and XANES measurements.

    Science.gov (United States)

    Caisso, Marie; Picart, Sébastien; Belin, Renaud C; Lebreton, Florent; Martin, Philippe M; Dardenne, Kathy; Rothe, Jörg; Neuville, Daniel R; Delahaye, Thibaud; Ayral, André

    2015-04-14

    Transmutation of americium in heterogeneous mode through the use of U1-xAmxO2±δ ceramic pellets, also known as Americium Bearing Blankets (AmBB), has become a major research axis. Nevertheless, in order to consider future large-scale deployment, the processes involved in AmBB fabrication have to minimize fine particle dissemination, due to the presence of americium, which considerably increases the risk of contamination. New synthesis routes avoiding the use of pulverulent precursors are thus currently under development, such as the Calcined Resin Microsphere Pelletization (CRMP) process. It is based on the use of weak-acid resin (WAR) microspheres as precursors, loaded with actinide cations. After two specific calcinations under controlled atmospheres, resin microspheres are converted into oxide microspheres composed of a monophasic U1-xAmxO2±δ phase. Understanding the different mechanisms during thermal conversion, that lead to the release of organic matter and the formation of a solid solution, appear essential. By combining in situ techniques such as XRD and XAS, it has become possible to identify the key temperatures for oxide formation, and the corresponding oxidation states taken by uranium and americium during mineralization. This paper thus presents the first results on the mineralization of (U,Am) loaded resin microspheres into a solid solution, through in situ XAS analysis correlated with HT-XRD.

  6. Microstructural features of the La{sub 1−x}Ca{sub x}FeO{sub 3−δ} solid solutions prepared via Pechini route

    Energy Technology Data Exchange (ETDEWEB)

    Gerasimov, E.Yu., E-mail: gerasimov@catalysis.ru [Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Pr. Acad. Lavrentieva 5, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090 (Russian Federation); Isupova, L.A. [Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Pr. Acad. Lavrentieva 5, Novosibirsk 630090 (Russian Federation); Tsybulya, S.V. [Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Pr. Acad. Lavrentieva 5, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090 (Russian Federation)

    2015-10-15

    Highlights: • La{sub 1−x}Ca{sub x}FeO {sub (3−δ)} (0 ≤ x ≤ 0.7) perovskite were prepared by Pechini method. • Planar defects in direction (1 0 1) were observed in the perovskite surface. • α-Fe{sub 2}O{sub 3} particles (1–10 nm) on the surface of perovskite were revealed. • Amount of α-Fe{sub 2}O{sub 3} particles on the perovskite surface grew with rising x values. - Abstract: Solid solutions with La{sub 1−x}Ca{sub x}FeO{sub 3−δ} (0 ≤ x ≤ 0.7) perovskite-like structure prepared via Pechini route have been investigated by using high resolution transmission electron microscopy and X-ray diffraction. Extended planar defects lying in (1 0 1) crystallographic planes and α-Fe{sub 2}O{sub 3} nanoparticles on the surface of perovskite microcrystals are characteristic of the samples under investigation. It was found that testing of the samples in catalytic deep CH{sub 4} oxidation process results in partial destruction of solid solutions with formation of planar defects in the bulk and α-Fe{sub 2}O{sub 3} particles on the surface.

  7. Photocatalytic degradation of H2S aqueous media using sulfide nanostructured solid-solution solar-energy-materials to produce hydrogen fuel.

    Science.gov (United States)

    Lashgari, Mohsen; Ghanimati, Majid

    2017-11-06

    H2S is a corrosive, flammable and noxious gas, which can be neutralized by dissolving in alkaline media and employed as H2-source by utilizing inside semiconductor-assisted/photochemical reactors. Herein, through a facile hydrothermal route, a ternary nanostructured solid-solution of iron, zinc and sulfur was synthesized in the absence and presence of Ag-dopant, and applied as efficient photocatalyst of hydrogen fuel production from H2S media. The effect of pH on the photocatalyst performance was scrutinized and the maximum activity was attained at pH=11, where HS(-) concentration is high. BET, diffuse reflectance and photoluminescence studies indicated that the ternary solid-solution photocatalyst, in comparison to its solid-solvent (ZnS), has a greater surface area, stronger photon absorption and less charge recombination, which justify its superiority. Moreover, the effect of silver-dopant on the photocatalyst performance was examined. The investigations revealed that although silver could boost the absorption of photons and increase the surface area, it could not appreciably enhance the photocatalyst performance due to its weak influence on retarding the charge-recombination process. Finally, the phenomenon was discussed in detail from mechanistic viewpoint. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. SOLID SOLUTION EFFECTS ON THE THERMAL PROPERTIES IN THE MgAl2O4-MgGa2O4

    Energy Technology Data Exchange (ETDEWEB)

    O' Hara, Kelley [University of Missouri, Rolla; Smith, Jeffrey D [ORNL; Sander, Todd P. [Missouri University of Science and Technology; Hemrick, James Gordon [ORNL

    2013-01-01

    Solid solution eects on thermal conductivity within the MgO-Al2O3-Ga2O3 system were studied. Samples with systematically varied additions of MgGa2O4 to MgAl2O4 were prepared and the laser ash technique was used to determine thermal diusivity at temperatures between 200C and 1300C. Heat capacity as a function of temperature from room temperature to 800C was also determined using dierential scanning calorimetry. Solid solution in the MgAl2O4-MgGa2O4 system decreases the thermal conductivity up to 1000C. At 200C thermal conductivity decreased 24% with a 5 mol% addition of MgGa2O4 to the system. At 1000C the thermal conductivity decreased 13% with a 5 mol% addition. Steady state calculations showed a 12.5% decrease in heat ux with 5 mol% MgGa2O4 considered across a 12 inch thickness.

  9. Solid state chemical model for the solubility behaviour of CaCO/sub 3/-MgCO/sub 3/ solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Driessens, F.C.M.; Verbeck, R.M.H.

    1981-08-01

    Mg-calcite can contain up to about 6 mol-% MgCO/sub 3/, dolomite between 40 and 51%. Solid solutions of CaCO/sub 3/ and MgCO/sub 3/ are unstable between 20 and 30 mol-% MgCO/sub 3/. The thermodynamic stability of dolomite with respect to calcite and magnesite amounts to about -6.8 kJ mol/sup -1/. It is shown that both the thermodynamical properties and the solubility behaviour of these solids can be explained with a solid-state chemical model based on the theory of subregular solid solutions. Evaluations of the parameters of the model resulted in a critical cluster size of about one unit cell for the dolomite structure. The fact that normal sea water is close to equilibrium with both calcite and dolomite means that the concentrations of Ca/sup 2 +/, Mg/sup 2 +/ and CO/sub 3//sup 2 -/ ions in sea water are restricted by fixed solubility relations.

  10. Ab initio Assessment of Bi1-xRExCuOS (RE=La, Gd, Y, Lu) Solid Solution as Semiconductor for Photochemical Water Splitting

    KAUST Repository

    Lardhi, Sheikha F.

    2017-04-12

    The investigation of BiCuOCh (Ch = S, Se and Te) semiconductors family for thermoelectric or photovoltaic materials is an increasing topic of research. These materials can also be considered for photochemical water splitting if one representative having a bandgap, Eg, around 2 eV can be developed. With this aim, we simulated the solid solution Bi1-xRExCuOS (RE = Y, La, Gd and Lu) from pure BiCuOS (Eg~1.1 eV) to pure RECuOS compositions (Eg~2.9 eV) by DFT calculations based on the HSE06 range-separated hybrid functional with inclusion of spin-orbit coupling. Starting from the thermodynamic stability of the solid solution, a large variety of properties were computed for each system including bandgap, dielectric constants, effective masses and exciton binding energies. We discussed the variation of these properties based on the relative organization of Bi and RE atoms in their common sublattice to offer a physical understanding of the influence of the RE doping of BiCuOS. Some compositions were found to give appropriate properties for water splitting application. Furthermore, we found that at low RE fractions the transport properties of BiCuOS are improved that can find applications beyond water splitting.

  11. The impact of local structure variation on thermal quenching of luminescence in Ca3MoxW1-xO6:Eu3+ solid solution phosphors

    Science.gov (United States)

    Wang, Chunhao; Ye, Shi; Li, Ye; Zhang, Qinyuan

    2017-03-01

    Near-ultraviolet (NUV, 365-410 nm) excitable white light emitting diodes require intense absorption in the NUV region for the tri-color phosphors (red, green, and blue). Optional red phosphor Ca3MoO6:Eu3+ meets the requirement of NUV absorption but suffers from severe quenching, while Ca3WO6:Eu3+ has good resistance to thermal quenching but could not absorb NUV light efficiently. It is requisite to investigate the candidate Ca3MoxW1-xO6:Eu3+ to balance the both effects. Results indicate that thermal quenching turns to be worse with an increase in Mo contents in the solid solutions with inevitable distortions or defects, especially when exciting the charge transfer band of WO6 and MoO6 groups. Temperature-dependent Raman spectroscopy is utilized to reveal the impact of structural variation in the quenching process since the variations influence the energy transfer between WO6/MoO6 groups and Eu3+ ions or among Eu3+ ions. Results show that the tilting or distortion of the Ca/W/MoO6 octahedral framework and weakened Eu3+-O bonds have large impacts on thermal quenching performance of Eu3+ luminescence in the solid solutions. The research would benefit the design of novel red phosphors.

  12. Reduced Activation W Alloys for Plasma Facing Materials

    Energy Technology Data Exchange (ETDEWEB)

    Waseem, Owais Ahmed; Kim, Seung Su; Lee, Jun Ho; Hong, Soon Hyung; Ryu, Ho Jin [KAIST, Daejeon (Korea, Republic of)

    2016-05-15

    In order to improve the in-service characteristics of W, thorough research on W-based composites, new W alloys and functionally graded materials are in progress. The limitations of conventional W alloys such as such as high brittleness, high activation energy for dislocation's mobility, reduced mechanical strength due to reaction phases, poor fabricability, defective passive layer, poor workability and unavailability of good number of alloy systems have persuaded us to divert research focus towards W-based high entropy alloys. The core effects of high entropy alloys include enhanced mixing entropy, sluggish diffusion, severe lattice distortion and cocktail effects. These key characteristics of high entropy alloys promote the formation of solid solution of 5 to 13 principle elements with exceptionally high strength, hardness, thermal stability, wear resistance, fatigue and creep resistance. Although the synthesis and exploitation of high entropy alloys have been in progress, this study comprises of our work in which we developed a reduced activation W-based high entropy alloy by not incorporating Mo, Cu, Nb and by reducing Ti content. In this research a powder metallurgical technique has been successfully used for producing novel W-based alloy with enhanced mechanical properties. An undiscovered potential of an unusual and so far disregarded powder metallurgical technique i. e. simple mixing in the development of W based material for future fusion power plants has been exploited by fabricating and analyzing a novel tungsten based high entropy alloy system x%W-(100-x)/4%(TaTiCrV). The characterization of HEA samples by XRD showed BCC crystal structure of the alloys. Microstructural examination SEM-EDS revealed the presence of bright and dark regions as W and Ti-rich phases, respectively. The evaluation of microstructures by using image processing software and Vickers hardness via micro-Vickers hardness tester showed the similar dependency of phase fraction and

  13. Thermodynamic study of phase equilibrium of superionic alloys of Ag3SBr1-xClx system in the concentration range 0.0-0.4 and temperature range 370-395 K

    Science.gov (United States)

    Moroz, M. V.; Prokhorenko, M. V.; Prokhorenko, S. V.; Reshetnyak, O. V.

    2017-03-01

    Thermodynamic assessment of the phase stability of the solid solutions of superionic alloys of the Ag3SBr1-xClx (I) system in the concentration range 0 ≤ x ≤ 0.4 and temperature range 370-395 K was performed. Partial functions of silver in the alloys of solid solution were used as the thermodynamic parameters. The values of partial thermodynamic functions were obtained with the use of the electromotive force method. Potential-forming processes were performed in electrochemical cells. Linear dependence of the electromotive force of cells on temperature was used to calculate the partial thermodynamic functions of silver in the alloys. The serpentine-like shape of the thermodynamic functions in the concentration range 0-4 is an evidence of the metastable state of solid solution. The equilibrium phase state of the alloys is predicted to feature the formation of the intermediate phase Ag3SBr0.76Cl0.24, and the solubility gap of the solid solution ranges of Ag3SBr0.76Cl0.24 and Ag3SBr.

  14. Effect of Microstructural Changes during Annealing on Thermoelectromotive Force and Resistivity of Electrodeposited Ni85.8Fe10.6W1.4Cu2.2 Alloy

    National Research Council Canada - National Science Library

    M. Spasojevic; A. Maricic; Z. Vukovic; S. Dukic; L. Ribic-Zelenovic

    2017-01-01

      Ni85.8Fe10.6W1.4Cu2.2 alloy powder containing nanocrystals of an FCC-structured solid solution of iron, tungsten, and copper in nickel embedded in an amorphous matrix was electrodeposited from an ammonia citrate solution...

  15. Hierarchical architectures of ZnS–In{sub 2}S{sub 3} solid solution onto TiO{sub 2} nanofibers with high visible-light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chengbin, E-mail: chem_cbliu@hnu.edu.cn [State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063 (China); Meng, Deshui; Li, Yue; Wang, Longlu [State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Liu, Yutang, E-mail: liuyutang@126.com [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Luo, Shenglian [State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063 (China)

    2015-03-05

    Graphical abstract: A unique hierarchical architecture of ZnS–In{sub 2}S{sub 3} solid solution onto TiO{sub 2} nanofibers was fabricated. The hierarchical heterostructures exhibit high visible light photocatalytic activity and outstanding recycling performance. - Highlights: • Novel hierarchical heterostructure of TiO{sub 2}@ZnS–In{sub 2}S{sub 3} solid solution. • Efficient inhibition of ZnS–In{sub 2}S{sub 3} solid solution aggregation. • High visible light photocatalytic activity. • Highly stable recycling performance. - Abstract: A unique hierarchical architecture of ZnS–In{sub 2}S{sub 3} solid solution nanostructures onto TiO{sub 2} nanofibers (TiO{sub 2}@ZnS–In{sub 2}S{sub 3}) has been successfully fabricated by simple hydrothermal method. The ZnS–In{sub 2}S{sub 3} solid solution nanostructures exhibit a diversity of morphologies: nanosheet, nanorod and nanoparticle. The porous TiO{sub 2} nanofiber templates effectively inhibit the aggregation growth of ZnS–In{sub 2}S{sub 3} solid solution. The formation of ZnS–In{sub 2}S{sub 3} solid solution is proved by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) and the intimate contact between TiO{sub 2} nanofibers and ZnS–In{sub 2}S{sub 3} solid solution favors fast transfer of photogenerated electrons. The trinary TiO{sub 2}@ZnS–In{sub 2}S{sub 3} heterostructures exhibit high adsorption capacity and visible light photocatalytic activity for the degradation of rhodamine B dye (RhB), remarkably superior to pure TiO{sub 2} nanofibers or binary structures (ZnS/TiO{sub 2} nanofibers, In{sub 2}S{sub 3}/TiO{sub 2} nanofibers and ZnS–In{sub 2}S{sub 3} solid solution). Under visible light irradiation the RhB photocatalytic degradation rate over TiO{sub 2}@ZnS–In{sub 2}S{sub 3} heterostructures is about 16.7, 12.5, 6.3, 5.9, and 2.2 times that over pure TiO{sub 2} nanofibers, ZnS nanoparticles, In{sub 2}S{sub 3}/TiO{sub 2} nanofibers, ZnS/TiO{sub 2} nanofibers, and Zn

  16. Kinetics of spinodal decomposition in driven nanocrystalline alloys

    Energy Technology Data Exchange (ETDEWEB)

    Razumov, I.K. [Institute of Metal Physics, Ural Branch of RAS, 18 Kovalevskaya Street, Ekaterinburg 620041 (Russian Federation)]. E-mail: rik@imp.uran.ru; Gornostyrev, Yu. N. [Institute of Metal Physics, Ural Branch of RAS, 18 Kovalevskaya Street, Ekaterinburg 620041 (Russian Federation); Yermakov, A. Ye. [Institute of Metal Physics, Ural Branch of RAS, 18 Kovalevskaya Street, Ekaterinburg 620041 (Russian Federation)

    2007-05-31

    The effect of grain boundaries (GB) on decomposition of solid solution was investigated in the framework generalized lattice gas model taking into account both local variation of chemical potential and the diffusion mobility near GB. It was shown that nonequilibrium GB can essentially change the phase equilibrium of alloy and surface directed spinodal decomposition (SDSD) caused by GB determines the precipitation morphology in nanograined materials. The increase of atomic mobility near GB can result in formation of lamellar structure propagating from GB to inside the grains and variation in morphology from lamellar to drop-like type structure when composition change.

  17. Phase separation of metastable CoCrFeNi high entropy alloy at intermediate temperatures

    OpenAIRE

    He, Feng; Wang, Zhijun; Wu, Qingfeng; Li, Junjie; Wang, Jincheng; Liu, C T

    2016-01-01

    The CoCrFeNi alloy is widely accepted as an exemplary stable base for high entropy alloys (HEAs). Although various investigations prove it to be stable solid solution, its phase stability is still suspicious. Here, we identified that the CoCrFeNi HEA was thermally metastable at intermediate temperatures, and composition decomposition occurred after annealed at 750oC for 800 hrs. The increased lattice distortion induced by minor addition of Al into the CoCrFeNi base accelerated the composition...

  18. Fatigue Crack Growth Mechanisms in High-Pressure Die-Cast Magnesium Alloys

    Science.gov (United States)

    El Kadiri, Haitham; Horstemeyer, M. F.; Jordon, J. B.; Xue, Yibin

    2008-01-01

    Microstructure-affected micromechanisms of fatigue crack growth operating near the limit plasticity regime were experimentally identified for the four main commercial high-pressure die-cast (HPDC) magnesium alloys: AM50, AM60, AZ91, and AE44. These fatigue micromechanisms manifested by the concomitant effects of casting pores, interdendritic Al-rich solid solution layer, β-phase particles, Mn-rich inclusions, rare earth-rich intermetallics, dendrite cell size, and surface segregation phenomena. These concomitant mechanisms clearly delineated the fatigue durability observed for the AM50, AM60, AZ91, and AE44 Mg alloys in both the low- and high-cycle fatigue regimes.

  19. Development of advanced high strength tantalum base alloys. Part 1: Screening investigation

    Science.gov (United States)

    Buckman, R. W., Jr.

    1971-01-01

    Five experimental tantalum alloy compositions containing 13-18% W+Re+Hf solid solution solute additions with dispersed phase strengthening achieved by carbon or nitrogen additions were prepared as 1.4 inch diameter ingot processed to 3/8 inch diameter rod and evaluated. Elevated temperature tensile and creep strength increased monotonically with increasing solute content. Room temperature elongation decreased for 20% to less than 2% as the solute content was increased above 16%. Phase identification indicated that the precipitating phase in the carbide containing alloys was Ta2C.

  20. Thermophysical and mechanical properties of V-(4-5)%Cr-(4-5)%Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J. [Oak Ridge National Lab., TN (United States)

    1998-03-01

    Solid solution V-Cr-Ti alloys exhibit a good combination of high thermal conductivity, adequate tensile strength, and low thermal expansion. The key thermophysical and mechanical properties for V-(4-5)%Cr-(4-5)%Ti alloys are summarized in this report. Some of these data are available in the ITER Materials Properties Handbook (IMPH), whereas other data have been collected from recent studies. The IMPH is updated regularly, and should be used as the reference point for design calculations whenever possible.

  1. Simulation of the first order phase transitions in binary alloys with variable mobility

    Science.gov (United States)

    L'vov, P. E.; Svetukhin, V. V.

    2017-10-01

    The first order phase transitions in binary alloys were simulated basing on the Cahn-Hilliard equation for metastable states with mobility depending on the local composition. The simulation was carried out utilizing the semi-implicit Fourier spectral method for 3D fragment of a solid solution satisfying the regular solution approximation. We defined kinetics of the main characteristics of phase distribution: nucleation rate, average size, concentration of precipitates and autocorrelation function etc. Peculiarities of different stages of binary alloy decomposition (nucleation, diffusion growth and coarsening) were analyzed both for constant and variable mobility.

  2. Effect of a solid solution on the steady-state creep behavior of an aluminum matrix composite

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, A.B.; Mahajan, Y.R. [Defence Metallurgical Research Lab., Hyderabad (India); Mishra, R.S. [Univ. of California, Davis, CA (United States). Dept. of Chemical Engineering and Materials Science

    1996-02-01

    The effect of an alloying element, 4 wt pct Mg, on the steady-state creep behavior of an Al-10 vol pct SiC{sub p} composite has been studied. The Al-4 wt pct Mg-10 vol pct SiC{sub p} composite has been tested under compression creep in the temperature range 573 to 673 K. The steady-state creep data of the composite show a transition in the creep behavior (regions 1 and 2) depending on the applied stress at 623 and 673 K. The low stress range data (region 1) exhibit a stress exponent of about 7 and an activation energy of 76.5 kJ mol{sup {minus}1}. These values conform to the dislocation-climb-controlled creep model with pipe diffusion as a rate-controlling mechanism. The intermediate stress range data (region 2) exhibit high and variable apparent stress exponents, 18 to 48, and activation energy, 266 kJ mol{sup {minus}1}, at a constant stress, {sigma} = 50 MPa, for creep of this composite. This behavior can be rationalized using a substructure-invariant model with a stress exponent of 8 and an activation energy close to the lattice self-diffusion of aluminum together with a threshold stress. The threshold stress and the creep strength of the Al-Mg-SiC{sub p} composite are compared with those of the Al-Mg-Al{sub 2}O{sub 3f} and 6061 Al-SiC{sub p,w} composites and discussed in terms of the load-transfer mechanism. Magnesium has been found to be very effective in improving the creep resistance of the Al-SiC{sub p} composite.

  3. On the Structural Features of Mechanically Alloyed Cu-Ag and Au-Co by Severe Cold and Cryogenic Plastic Deformation

    Science.gov (United States)

    Tolmachev, T.; Pilyugin, V.; Ancharov, A.; Patselov, A.; Chernyshev, E.; Zolotarev, K.

    The effect of cryogenic temperature on the formation of solid solutions by mechanical alloying (MA) was studied using synchrotron diffraction and some additional methods. Two systems with different positive enthalpy of mixing (Cu-Ag i Au-Co) were involved. MA by severe plastic deformation at 293 K and 80 K leads to the formation of fcc substitutional solid solutions, with the excess of the equilibrium concentration for both systems. The effect of cryogenic deformation consists in smaller dissolution of the original basic element of the charge (Cu) for Cu-Ag solid solution and in increasing of solute (Co) for Au-Co one. Diffraction experiments were performed at the SR beamline №4 of the VEPP-3 storage ring.

  4. Identification of phase structure of plated zinc alloys based on a linear voltammetry in alkaline solutions

    Directory of Open Access Journals (Sweden)

    Lina V. Petrenko

    2016-12-01

    Full Text Available The purpose of research was the development of new and effective technique of electroplatings phase composition analysis by inversion voltammetric methods. As a result the possibility of the phase composition of the plated zinc-based alloys identification using anodic linear voltammetry in alkaline solutions was shown. The phase composition Zn–(0.27–9.4% Fe alloy electroplated from alkaline zincate solutions was defined based on voltammetry data. As part of the Zn–Fe alloys the phase of hexagonal structure was found which is absent in the equilibrium phase diagram. The ratio of hexagonal crystal lattice axes (c/a and the electron concentration (e/a for this phase are significantly different from the corresponding values for the primary solid solution η. From the analysis of c/a and e/a values of investigated Zn–Fe alloy the defined phase was identified as a solid solution phase type ε. It also was shown that anodic linear voltammetry accomplished in alkaline solutions is more sensitive to the identification of the phase composition of zinc alloys than the traditional X-ray method and stripping voltammetry.

  5. Morphology and microstructure of rapidly solidified tin-lead alloy powders

    Directory of Open Access Journals (Sweden)

    Xiang Qingchun

    2014-09-01

    Full Text Available Sn60Pb40 alloy powders were fabricated using the planar flow casting (PFC atomization process. By using OM, SEM and EPMA, the characteristics of the morphologies and microstructures of the powders have been investigated. It is observed that the environment of ambient gas in the atomization box has great effects on the morphology of the alloy powders. The microstructures of Sn60Pb40 alloy powders produced by the PFC atomization process are completely composed of eutectic, which is made up of both oversaturated α solid solution and β solid solution. The microstructures of small size powders are extraordinarily undeveloped dendritic eutectic, in which the large majority of the α phase appears nearly spherical, evidently since the cooling rate is higher and the under-cooling is larger. As for the large size powders, since the cooling rate and undercooling are relatively low, lamellar α phase apparently increases in the eutectic microstructures of these powders, and there is even typical lamellar eutectic structure clearly observed in some micro-areas. After remelting tests by DTA, the microstructures of small size powders are transformed, which become composed of large crumby α phase and eutectic (α+β, while those of large size powders change into classical tin-lead structures of primary α phase plus lamellar eutectic (α+β. By studying the microstructures of tin-lead alloy powders, a model has been proposed to predict the microstructure formation of Sn60Pb40 alloy powders.

  6. A note on the different crystalline features of the EuMnO3-based solid solutions as a function of the modifying cation nature

    Directory of Open Access Journals (Sweden)

    Peña, O.

    2010-12-01

    Full Text Available The structural properties of solid solutions based on EuMnO3, in which Eu has been substituted by divalent Ca2+ and Mn by the divalent cation Ni2+ or the variable valence cation Co2+-Co3+ have been studied by X-ray diffraction (XRD and X-ray absorption spectroscopy (XAS. These substitutions lead to changes in the lattice parameters and the symmetry of the orthorhombic, O’ perovskite-type of the pristine compound EuMnO3. The structural changes depend on several factors. Solid solutions Eu(Mn,NiO3 and Eu(Mn,CoO3 change from the O’-type to O-type orthorhombic perovskite symmetry when the content of the Mn3+ cation decreases due to the progressive substitution by Ni and Co. This change occurs for a percentage of the Ni2+ cation of 20 at%, whereas for the Co cation, only 10 at% are needed for such a transition. (Eu,CaMnO3 solid solutions showed a different behaviour. Even at an amount as high as 50 at% Ca2+ there is no transition from O’ to O-type orthorhombic perovskite symmetry. The tolerance factor, t, increases monotonically for both Eu(Mn,NiO3 and (Eu,CaMnO3, while for Eu(Mn,CoO3 it first decreases and then increases. The increase is lower for Ni-based and Co-based samples than for the Ca-based ones.Las propiedades estructurales de las soluciones sólidas basadas en EuMnO3, en donde Eu ha sido sustituido por Ca2+, y Mn por Ni2+ o por un catión de valencia variable tal como Co, (II ó III han sido estudiadas por Difracción de Rayos X, (DRX. Estas sustituciones llevan a cambios en los parámetros de red y en la simetría de la perovskita tipo O’ propia del compuesto EuMnO3. Los cambios estructurales dependen de la cantidad y del tipo de catión sustituyente. Ni y Co inducen un cambio desde la estructura tipo O’ a la O para 20 at% Ni y 10 at% Co respectivamente. Por su parte, la incorporación de Ca en lugares A induce este cambio para x(Ca > 50 at%. El factor de tolerancia de la estructura perovskita también muestra un comportamiento

  7. Solid solution studies of layered honeycomb-ordered phases O₃–Na₃M₂SbO₆ (M=Cu, Mg, Ni, Zn)

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Whitney; Berthelot, Romain; Sleight, A.W. [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States); Subramanian, M.A., E-mail: mas.subramanian@oregonstate.edu [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States)

    2013-05-01

    Complete solid solutions with the composition Na₃M2–xxSbO₆ where M, M´=Cu, Mg, Ni, Zn have been synthesized by conventional solid state techniques and were investigated using X-ray diffraction, magnetic susceptibility and optical measurements. All compositions crystallize in a monoclinic unit cell and exhibit a layered structure with a honeycomb cationic ordering within the slabs. These compounds also exhibit Curie–Weiss behavior at high temperature and the magnetic moment values verify the presence of Cu²⁺ and/or Ni²⁺. The antiferromagnetic order of Na₃Ni₂SbO₆ is suppressed upon substitution of Ni²⁺ with Mg²⁺ or Zn²⁺. The spin gap observed in Na₃Cu₂SbO₆ is also suppressed by substitution of Cu²⁺ with Mg²⁺ or Zn²⁺. The Na₃Ni2–xCuxSbO₆ compositions follow an expected transition from an antiferromagnetic ordering to the spin gap of the copper end member. The estimated band gaps for these compounds have been determined from diffuse reflectance measurements. - Graphical abstract: Complete solid solutions with the composition Na₃M2–xxSbO₆ where M, M´=Cu, Mg, Ni, Zn have been synthesized using conventional solid state techniques and were investigated using X-ray diffraction, magnetism and optical measurements. Based on an ionic radii point of view the lattice parameter shifting in the composition containing copper are opposite of what would be expected. The Cu²⁺ is Jahn–Teller active which distorts the C2/m cell, increasing the β angle between the a and c parameters and explains this shifting pattern. Highlights: • The solid solutions O₃–Na₃M2–xxSbO₆(M, M´=Cu, Mg, Ni, Zn) were synthesized. • These compounds crystallize in the C2/m space group. • The Jahn–Teller active Cu²⁺ causes distortion of the monoclinic cell. • The Cu²⁺ spin gap magnetic properties are diluted upon 25% substitution

  8. VANADIUM ALLOYS

    Science.gov (United States)

    Smith, K.F.; Van Thyne, R.J.

    1959-05-12

    This patent deals with vanadium based ternary alloys useful as fuel element jackets. According to the invention the ternary vanadium alloys, prepared in an arc furnace, contain from 2.5 to 15% by weight titanium and from 0.5 to 10% by weight niobium. Characteristics of these alloys are good thermal conductivity, low neutron capture cross section, good corrosion resistance, good welding and fabricating properties, low expansion coefficient, and high strength.

  9. V(H)H (nanobody) directed against human glycophorin A: a tool for autologous red cell agglutination assays.

    Science.gov (United States)

    Habib, Ibrahim; Smolarek, Dorota; Hattab, Claude; Grodecka, Magdalena; Hassanzadeh-Ghassabeh, Gholamreza; Muyldermans, Serge; Sagan, Sandrine; Gutiérrez, Carlos; Laperche, Syria; Le-Van-Kim, Caroline; Aronovicz, Yves Colin; Wasniowska, Kazimiera; Gangnard, Stephane; Bertrand, Olivier

    2013-07-01

    The preparation of a V(H)H (nanobody) named IH4 that recognizes human glycophorin A (GPA) is described. IH4 was isolated by screening a library prepared from the lymphocytes of a dromedary immunized by human blood transfusion. Phage display and panning against GPA as the immobilized antigen allowed isolating this V(H)H. IH4, representing 67% of the retrieved V(H)H sequences, was expressed as a soluble correctly folded protein in SHuffle Escherichia coli cells, routinely yielding approximately 100 mg/L fermentation medium. Because IH4 recognizes GPA independently of the blood group antigens, it recognizes red cells of all humans with the possible exception of those with some extremely rare genetic background. The targeted linear epitope comprises the GPA Y52PPE55 sequence. Based on surface plasmon resonance results, the dissociation constant of the IH4-GPA equilibrium is 33 nM. IH4 is a stable protein with a transition melting temperature of 75.8 °C (measured by differential scanning calorimetry). As proof of concept, we fused HIV p24 to IH4 and used the purified construct expressed in E. coli to show that IH4 was amenable to the preparation of autologous erythrocyte agglutination reagents: reconstituted blood prepared with serum from an HIV-positive patient was readily agglutinated by the addition of the bifunctional reagent. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. Formation and characterization of Al–Ti–Nb alloys by electron-beam surface alloying

    Energy Technology Data Exchange (ETDEWEB)

    Valkov, S., E-mail: stsvalkov@gmail.com [Institute of Electronics, Bulgarian Academy of Science, 72 Tzarigradsko Chaussee blvd., 1784 Sofia (Bulgaria); Petrov, P. [Institute of Electronics, Bulgarian Academy of Science, 72 Tzarigradsko Chaussee blvd., 1784 Sofia (Bulgaria); Lazarova, R. [Institute of Metal Science, Equipment and Technologies with Hydro and Aerodynamics Center, Bulgarian Academy of Science, 67 Shipchenski Prohod blvd., 1574 Sofia (Bulgaria); Bezdushnyi, R. [Department of Solid State Physics and Microelectronics, Faculty of Physics, Sofia University “St. Kliment Ohridsky”, 1164 Sofia (Bulgaria); Dechev, D. [Institute of Electronics, Bulgarian Academy of Science, 72 Tzarigradsko Chaussee blvd., 1784 Sofia (Bulgaria)

    2016-12-15

    Highlights: • Al–Ti–Nb surface alloys have been successfully obtained by electron-beam surface alloying technology. • The alloys consist of (Ti,Nb)Al{sub 3} fractions, distributed in the biphasic structure of (Ti,Nb)Al{sub 3} particles dispersed in α-Al. • The alloying speed does not affect the lattice parameters of (Ti,Nb)Al{sub 3} and, does not form additional stresses, strains etc. • It was found that lower velocity of the specimen motion during the alloying process develops more homogeneous structures. • The measured hardness of (Ti,Nb)Al{sub 3} compound reaches 775 HV[kg/cm{sup 2}] which is much greater than the values of NbAl{sub 3}. - Abstract: The combination of attractive mechanical properties, light weight and resistance to corrosion makes Ti-Al based alloys applicable in many industrial branches, like aircraft and automotive industries etc. It is known that the incorporation of Nb improves the high temperature performance and mechanical properties. In the present study on Al substrate Ti and Nb layers were deposited by DC (Direct Current) magnetron sputtering, followed by electron-beam alloying with scanning electron beam. It was chosen two speeds of the specimen motion during the alloying process: V{sub 1} = 0.5 cm/s and V{sub 2} = 1 cm/s. The alloying process was realized in circular sweep mode in order to maintain the melt pool further. The obtained results demonstrate a formation of (Ti,Nb)Al{sub 3} fractions randomly distributed in biphasic structure of intermetallic (Ti,Nb)Al{sub 3} particles, dispersed in α-Al solid solution. The evaluated (Ti,Nb)Al{sub 3} lattice parameters are independent of the speed of the specimen motion and therefore the alloying speed does not affect the lattice parameters and thus, does not form additional residual stresses, strains etc. It was found that lower velocity of the specimen motion during the alloying process develops more homogeneous structures. The metallographic analyses demonstrate a

  11. Effects of Palladium Content, Quaternary Alloying, and Thermomechanical Processing on the Behavior of Ni-Ti-Pd Shape Memory Alloys for Actuator Applications

    Science.gov (United States)

    Bigelow, Glen

    2008-01-01

    The need for compact, solid-state actuation systems for use in the aerospace, automotive, and other transportation industries is currently driving research in high-temperature shape memory alloys (HTSMA) having transformation temperatures above 100 C. One of the basic high temperature systems under investigation to fill this need is NiTiPd. Prior work on this alloy system has focused on phase transformations and respective temperatures, no-load shape memory behavior (strain recovery), and tensile behavior for selected alloys. In addition, a few tests have been done to determine the effect of boron additions and thermomechanical treatment on the aforementioned properties. The main properties that affect the performance of a solid state actuator, namely work output, transformation strain, and permanent deformation during thermal cycling under load have mainly been neglected. There is also no consistent data representing the mechanical behavior of this alloy system over a broad range of compositions. For this thesis, ternary NiTiPd alloys containing 15 to 46 at.% palladium were processed and the transformation temperatures, basic tensile properties, and work characteristics determined. However, testing reveals that at higher levels of alloying addition, the benefit of increased transformation temperature begins to be offset by lowered work output and permanent deformation or "walking" of the alloy during thermal cycling under load. In response to this dilemma, NiTiPd alloys have been further alloyed with gold, platinum, and hafnium additions to solid solution strengthen the martensite and parent austenite phases in order to improve the thermomechanical behavior of these materials. The tensile properties, work behavior, and dimensional stability during repeated thermal cycling under load for the ternary and quaternary alloys were compared and discussed. In addition, the benefits of more advanced thermomechanical processing or training on the dimensional stability of

  12. A microstructure-based model for describing strain softening during compression of Al-30%wt Zn alloy

    Directory of Open Access Journals (Sweden)

    M Borodachenkova

    2016-09-01

    Full Text Available A microstructural-based model, describing the plastic behavior of Al-30wt% Zn alloy, is proposed and the effect of solid solution decomposition, Orowan looping, twinning and grain refinement is analyzed. It is assumed that the plastic deformation process is dominated by strain-induced solute diffusion and dislocation motion. To capture the essential physics, a law describing the evolution of the mean free path of dislocations with plastic strain is proposed which reproduces the experimentally observed strain softening.

  13. Simulation of ceramic materials relevant for nuclear waste management: Case of La{sub 1−x}Eu{sub x}PO{sub 4} solid solution

    Energy Technology Data Exchange (ETDEWEB)

    Kowalski, Piotr M., E-mail: p.kowalski@fz-juelich.de; Ji, Yaqi; Li, Yan; Arinicheva, Yulia; Beridze, George; Neumeier, Stefan; Bukaemskiy, Andrey; Bosbach, Dirk

    2017-02-15

    Using powerful computational resources and state-of-the-art methods of computational chemistry we contribute to the research on novel nuclear waste forms by providing atomic scale description of processes that govern the structural incorporation and the interactions of radionuclides in host materials. Here we present various results of combined computational and experimental studies on La{sub 1−x}Eu{sub x}PO{sub 4} monazite-type solid solution. We discuss the performance of DFT + U method with the Hubbard U parameter value derived ab initio, and the derivation of various structural, thermodynamic and radiation-damage related properties. We show a correlation between the cation displacement probabilities and the solubility data, indicating that the binding of cations is the driving factor behind both processes. The combined atomistic modeling and experimental studies result in a superior characterization of the investigated material.

  14. The high-temperature heat capacity of the (Th,U)O2 and (U,Pu)O2 solid solutions

    Science.gov (United States)

    Vălu, S. O.; Beneš, O.; Manara, D.; Konings, R. J. M.; Cooper, M. W. D.; Grimes, R. W.; Guéneau, C.

    2017-02-01

    The enthalpy increment data for the (Th,U)O2 and (U,Pu)O2 solid solutions are reviewed and complemented with new experimental data (400-1773 K) and many-body potential model simulations. The results of the review show that from room temperature up to about 2000 K the enthalpy data are in agreement with the additivity rule (Neumann-Kopp) in the whole composition range. Above 2000 K the effect of Oxygen Frenkel Pair (OFP) formation leads to an excess enthalpy (heat capacity) that is modeled using the enthalpy and entropy of OFP formation from the end-members. A good agreement with existing experimental work is observed, and a reasonable agreement with the results of the many-body potential model, which indicate the presence of the diffuse Bredig (superionic) transition that is not found in the experimental enthalpy increment data.

  15. The key role of the composition and structural features in fluoride ion conductivity in tysonite Ce1-xSrxF3-x solid solutions.

    Science.gov (United States)

    Dieudonné, Belto; Chable, Johann; Body, Monique; Legein, Christophe; Durand, Etienne; Mauvy, Fabrice; Fourcade, Sébastien; Leblanc, Marc; Maisonneuve, Vincent; Demourgues, Alain

    2017-03-14

    Pure tysonite-type Ce1-xSrxF3-x solid solutions for 0 ≤ x conductivity found for Ce0.975Sr0.025F2.975 (3 × 10-4 S cm-1 at RT, Ea = 0.31 eV) is correlated to the largest dispersion of F2-(Ce,Sr) and F3-(Ce,Sr) distances which induces the maximum sheet buckling. Such a relationship between composition, structural features and fluoride ion conductivity is extended to other tysonite-type fluorides. The key role of the difference between AE2+ and RE3+ ionic radii and of the thickness of the slab buckling is established and could allow designing new ionic conductors.

  16. Synthesis and thermostructural studies of a CuFe(1-x)Cr(x)O(2) delafossite solid solution with 0

    Science.gov (United States)

    Lalanne, M; Barnabé, A; Mathieu, F; Tailhades, Ph

    2009-07-06

    In this work, different CuFe(1-x)Cr(x)O(2) compositions with 0 solid solution was studied by thermogravimetric analysis and high-temperature X-ray diffraction experiments under an air atmosphere up to 1000 degrees C. For x = 0, CuFeO(2) is oxidized into the spinel (CuFe(2)O(4)) and copper monoxide (CuO) phases, whereas for x = 1, CuCrO(2) is thermally stable. For all of the intermediate compositions (0 < x < 1), complex oxidation, reduction, and phase transitions between delafossite and spinel have been observed. chromium tends to stabilize the stoichiometric delafossite phase, while iron favors the delafossite-to-spinel phase transition.

  17. Structural, morphology and optical properties of Zn(1-x)CdxO solid solution grown on c-plane sapphire substrate

    Science.gov (United States)

    Fouzri, A.; Boukadhaba, M. A.; Oumezzine, M.; Bchetnia, A.; Sallet, V.

    2012-06-01

    Zn(1-x)CdxO solid solutions with a composition ranging from pure ZnO up to x=0.046 have been grown on cplane sapphire substrates by using metal organic chemical vapor deposition (MO-CVD). The lattice deformation, morphology and optical properties of these films were examined in detail using high resolution X-ray diffraction, atomic force microscopy (AFM) and photoluminescence (PL) as Cd incorporation. Our study reveals significant microstructure modification of Zn(1-x)CdxO from x≥0.7% but single phase of wurtzite structure is maintained for all films. The Pl spectra and the band gap of the Zn(1-x)CdxO film show red shift to visible light range which is interpreted in terms of band gap modulation due to Cd incorporation. Increase of Cd content leads to the emission broadening with growing lower energy peak (at 10K) and degraded crystallinity.

  18. Structural, morphology and optical properties of Zn(1-xCdxO solid solution grown on c-plane sapphire substrate

    Directory of Open Access Journals (Sweden)

    Bchetnia A.

    2012-06-01

    Full Text Available Zn(1-xCdxO solid solutions with a composition ranging from pure ZnO up to x=0.046 have been grown on cplane sapphire substrates by using metal organic chemical vapor deposition (MO-CVD. The lattice deformation, morphology and optical properties of these films were examined in detail using high resolution X-ray diffraction, atomic force microscopy (AFM and photoluminescence (PL as Cd incorporation. Our study reveals significant microstructure modification of Zn(1-xCdxO from x≥0.7% but single phase of wurtzite structure is maintained for all films. The Pl spectra and the band gap of the Zn(1-xCdxO film show red shift to visible light range which is interpreted in terms of band gap modulation due to Cd incorporation. Increase of Cd content leads to the emission broadening with growing lower energy peak (at 10K and degraded crystallinity.

  19. Recent Progress in High Entropy Alloy Research

    Science.gov (United States)

    MacDonald, B. E.; Fu, Z.; Zheng, B.; Chen, W.; Lin, Y.; Chen, F.; Zhang, L.; Ivanisenko, J.; Zhou, Y.; Hahn, H.; Lavernia, E. J.

    2017-10-01

    Since their discovery in 2004, high-entropy alloys (HEAs) have generated significant interest from the scientific community. Based on a multi-principal element design approach, HEAs are engineered to possess a unique random solid solution (RSS) crystalline structure, in which each of the constituent elements has an equal probability of occupying a given lattice site. Published literature reports that certain HEAs exhibit exceptional chemical, physical, mechanical and functional properties that are attributed to the presence of a RSS phase. Not surprisingly, research on HEAs has begun to expand at an accelerated rate. The scientific and engineering topics being studied include: experimentally measuring various properties in HEA systems, understanding the effect of the RSS on these properties, and developing methods for predicting the formation of RSS phases. Accordingly, the goal of this brief review is to introduce the field of HEAs, discuss their core concepts, highlight exceptional properties, and discuss current design aspects.

  20. Brazing of Titanium with Aluminium Alloys

    Directory of Open Access Journals (Sweden)

    Winiowski A.

    2017-06-01

    Full Text Available This study presents results of vacuum diffusion brazing of Grade 2 titanium with 6082 (AlMg1Si0.6Cu0.3 aluminium alloy using B-Ag72Cu-780 (Ag72Cu28 grade silver brazing metal as an interlayer. Brazed joints underwent shear tests, light-microscopy-based metallographic examinations and structural examinations using scanning electron microscopy (SEM and X-ray energy dispersive spectrometry (EDS. The highest quality and shear strength of 20 MPa was characteristic of joints brazed at 530°C with a 30-minute hold. The structural examinations revealed that in diffusion zone near the boundary with titanium the braze contained solid solutions based on hard and brittle Ti-Al type intermetallic phases determining the strength of the joints.

  1. Synthesis of {beta}-phase Ag{sub 1-x}Cu{sub x}I (x = 0-0.5) solid solutions nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xianli [Key Laboratory of Bionic Engineering, College of Biology and Agriculture Engineering, Jilin University, Nanling Campus, Changchun 130025 (China); Jilin Weather Modification Office, Changchun 130062 (China); Zhang, Jinghong [Key Laboratory of Automobile Materials, College of Materials Science and Engineering, Jilin University, Nanling Campus, Changchun 130025 (China); Jilin Weather Modification Office, Changchun 130062 (China); Zhang, Guilan, E-mail: lxl5211@126.com [Key Laboratory of Bionic Engineering, College of Biology and Agriculture Engineering, Jilin University, Nanling Campus, Changchun 130025 (China); Jiang, Zhonghao [Key Laboratory of Automobile Materials, College of Materials Science and Engineering, Jilin University, Nanling Campus, Changchun 130025 (China); Jin, Dezhen [Jilin Weather Modification Office, Changchun 130062 (China)

    2011-06-15

    Research highlights: {yields} Wet-chemical-chelating reaction processing has been used to synthesized A series of single {beta}-phase nano-Ag{sub 1-x}Cu{sub x}I (x = 0-0.5) solid solutions powders. {yields} Citric acid as complexing agent takes part in the process of chemical reaction and the chemical reactions can be described in this paper. {yields} The lattice parameters have been ascertained by the results of XRD. {yields} Crystalline sizes, which decrease with copper iodide concentration increasing, have been demonstrated by XRD and TEM. -- Abstract: A series of single {beta}-phase nano-Ag{sub 1-x}Cu{sub x}I (x = 0-0.5) solid solutions powders were synthesized by wet-chemical-chelating reaction processing and citric acid used as complexing agent. The Ag{sub 1-x}Cu{sub x}I powders were determined by X-ray diffraction and transmission electron microscopy. It was demonstrated that the crystalline size and lattice parameter of the Ag{sub 1-x}Cu{sub x}I powders decrease with an increase in the amount of CuI substitution. The copper in the lattice of the Ag{sub 1-x}Cu{sub x}I can effectively prevent the crystalline growth of the Ag{sub 1-x}Cu{sub x}I powders and citrate used in the Ag{sub 1-x}Cu{sub x}I powders synthesized process can accelerate single {beta}-phase crystalline structure formation.

  2. La-Sr-Ni-Co-O based perovskite-type solid solutions as catalyst precursors in the CO{sub 2} reforming of methane

    Energy Technology Data Exchange (ETDEWEB)

    Valderrama, Gustavo [Laboratorio de Catalisis, Petroleo y Petroquimica, Unidad de Estudios Basicos, Universidad de Oriente - Nucleo Bolivar, La Sabanita - Calle San Simon, Estado Bolivar 8001 (Venezuela); Kiennemann, Alain [Laboratoire des Materiaux et Procedes pour la Catalyse, UMR 7515, ECPM, Universite Louis Pasteur, 25 rue Becquerel, 67087 Strasbourg Cedex 2 (France); Goldwasser, Mireya R. [Centro de Catalisis, Petroleo y Petroquimica, Facultad de Ciencias - Universidad Central de Venezuela. Paseo los Ilustres, Los Chaguaramos, Caracas 1040 (Venezuela)

    2010-04-02

    La{sub 1-x}Sr{sub x}Ni{sub 0.4}Co{sub 0.6}O{sub 3} and La{sub 0.8}Sr{sub 0.2}Ni{sub 1-y}Co{sub y}O{sub 3} solid solutions with perovskite-type structure were synthesized by the sol-gel resin method and used as catalytic precursors in the dry reforming of methane with CO{sub 2} to syngas, between 873 and 1073 K at atmospheric pressure under continuous flow of reactant gases with CH{sub 4}/CO{sub 2} = 1 ratio. These quaternary oxides were characterized by X-ray diffraction (XRD), BET specific surface area and temperature-programmed reduction (TPR) techniques. XRD analyses of the more intense diffraction peaks and cell parameter measurements showed formation of La-Sr-Ni-Co-O solid solutions with La{sub 0.9}Sr{sub 0.1}CoO{sub 3} and/or La{sub 0.9}Sr{sub 0.1}NiO{sub 3} as the main crystallographic phases present on the solids depending on the degree of substitution. TPR analyses showed that Sr doping decreases the temperature of reduction via formation of intermediary species producing Ni{sup 0}, Co{sup 0} with particle sizes in the range of nanometers over the SrO and La{sub 2}O{sub 3} phases. These metallic nano particles highly dispersed in the solid matrix are responsible for the high activity shown during the reaction and avoid carbon formation. The presence of Sr in doping quantities also promotes the secondary reactions of carbon formation and water-gas shift in a very small extension during the dry reforming reaction. (author)

  3. NaCu(Ta1-yNby)4O11 solid solution: A tunable band gap spanning the visible-light wavelengths

    Science.gov (United States)

    Palasyuk, Olena; Maggard, Paul A.

    2012-07-01

    The new solid-solution NaCu(Ta1-yNby)4O11 (0≤y≤0.7) was synthesized by solid-state methods in the form of bulk powders that ranged from light-yellow to brown colored and were characterized by powder X-ray diffraction techniques (Space group R-3c (#167); Z=6; a=6.214(1)-6.218(1) Å and c=36.86(1)-36.94(1) Å). Full-profile Rietveld refinements confirmed a site-differentiated ordering of the Cu(I) and Na cations, i.e., occupying the 12c (linear environment) and 18d (seven-coordinate environment) crystallographic sites respectively. Conversely, a statistical mixture of Ta(V) and Nb(V) cations occurred over the 6b (octahedral environment) or the 18e (pentagonal-bipyramidal environment) crystallographic sites, without any preferential segregation. The UV-Vis diffuse reflectance spectra showed a significant red-shift of the optical bandgap size (indirect) from ˜2.70 eV to ˜1.80 eV across the solid solution with increasing Nb(V) content. Electronic-structure calculations using the tight-binding linear-muffin-tin-orbital approach showed that the reduction in bandgap size arises from the introduction of the lower-energy Nb 4d0 orbitals into the conduction band and consequently a lower energy of the conduction band edge. The lowest-energy bandgap transitions were found to be derived from electronic transitions between the filled Cu(I) and the empty Nb(V) d-orbitals, with a small amount of mixing with the O 2p orbitals. The resulting conduction and valence band energies are found to approximately bracket the redox potentials for water reduction and oxidation, and meeting the thermodynamic requirements for photocatalytic water-splitting reactions.

  4. Fabrication of Ta2O5 Dispersion-Strengthened Mo-Si-B Alloy by Powder Metallurgical Method

    Science.gov (United States)

    Byun, Jong Min; Choi, Won June; Bang, Su-Ryong; Park, Chun Woong; Do Kim, Young

    2017-04-01

    In this study, we investigate the effect of oxide dispersion strengthening on mechanical properties by dispersion of nano-sized Ta2O5 particles in Mo-Si-B alloy. A Mo-Si-B core-shell powder consisting of two intermetallic compounds of Mo5SiB2 and Mo3Si as the core and nano-sized Mo solid solution surrounding intermetallic compounds was fabricated by chemical vapor transport. And Mo-Si-B core-shell powder with uniformly dispersed nano-sized Ta2O5 particles on the surface of a Mo solid solution shell was produced by a wet blending process with TaCl5 solution and heat treatment. Then, pressureless sintering was performed at 1400°C for 3 h under a H2 atmosphere. The hardness and fracture toughness of the Ta2O5-dispersed Mo-Si-B alloy were measured using Vickers hardness and 3-point bending tests, respectively. The Vickers hardness and fracture toughness of the fabricated Mo-Si-B-Ta2O5 alloy were more improved than that of the Mo-Si-B alloy fabricated using core-shell powder with no addition of Ta2O5 particles (Mo-Si-B alloy: 353 Hv, 13.5 MPa·√m, Mo-Si-B-Ta2O5 alloy: 509 Hv, 15.1 MPa·√m).

  5. The microstructure and properties of tungsten alloying layer on copper by high-current pulse electron beam

    Science.gov (United States)

    Zhang, Conglin; Lv, Peng; Cai, Jie; Peng, Ching-Tun; Jin, Yunxue; Guan, Qingfeng

    2017-11-01

    In this paper, tungsten (W) was chosen to be an alloying element into the surface layer of commercial pure (cp) copper (Cu) to enhance the surface properties after surface alloying by high current pulsed electron beam (HCPEB). After HCPEB irradiation, part of the blended powder was dissolved into the substrate surface to form an alloyed layer, which has defect structures consisting of dislocation cells/walls. The presence of defect structures induced by HCPEB irradiation provides a large amount of paths for W atoms to form solid solution and ultrafine W particles. The surface hardening is ascribed to intense plastic deformation via stress, sub-grain strengthening, along with the alloying elements via precipitation hardening and/or the solid solution strengthening. The corrosion performance, tested in 3.5% NaCl solution, was significantly enhanced after surface alloying. The improvement in corrosion resistance is essentially attributed to the combination of the structure defects and the addition of alloying elements to form more stable passive film.

  6. Morphology Evolution on the Fracture Surface and Fracture Mechanisms of Multiphase Nanostructured ZrCu-Base Alloys

    Directory of Open Access Journals (Sweden)

    Feng Qiu

    2017-03-01

    Full Text Available A multiphase nanostructured ZrCu-base bulk alloy which showed a unique microstructure consisting of sub-micrometer scale Zr2Cu solid solution, nano-sized twinned plate-like ZrCu martensite (ZrCu (M, and retained ZrCu (B2 austenite was fabricated by copper mold casting. The observation of periodic morphology evolution on the fracture surface of the multiphase nanostructured ZrCu-base alloys has been reported, which suggested a fluctuant local stress intensity along the crack propagation. It is necessary to investigate the compressive deformation behavior and the fracture mechanism of the multiphase alloy and the relation to the unique microstructures. The results obtained in this study provide a better understanding of the deformation and fracture mechanisms of multiphase hybrid nanostructured ZrCu-based alloys and give guidance on how to improve the ductility/toughness of bulk ZrCu-based alloys.

  7. Influence of Solution Heat Treatment on Structure and Mechanical Properties of ZnAl22Cu3 Alloy

    Directory of Open Access Journals (Sweden)

    Michalik R.

    2016-09-01

    Full Text Available The influence of solution heat treatment at 385°C over 10 h with cooling in water on the structure, hardness and strength of the ZnAl22Cu3 eutectoid alloy is presented in the paper. The eutectoid ZnAl22Cu3 alloy is characterized by a dendritic structure. Dendrites are composed of a supersaturated solid solution of Al in Zn. In the interdendritic spaces a eutectoid mixture is present, with an absence of the ε (CuZn4 phase. Solution heat treatment of the ZnAl22Cu3 alloy causes the occurrence of precipitates rich in Zn and Cu, possibly ε phase. Solution heat treatment at 385°C initially causes a significant decrease of the alloy hardness, although longer solution heat treatment causes a significant increase of the hardness as compared to the as-cast alloy.

  8. Effect of electron count and chemical complexity in the Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor.

    Science.gov (United States)

    von Rohr, Fabian; Winiarski, Michał J; Tao, Jing; Klimczuk, Tomasz; Cava, Robert Joseph

    2016-11-15

    High-entropy alloys are made from random mixtures of principal elements on simple lattices, stabilized by a high mixing entropy. The recently discovered body-centered cubic (BCC) Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor appears to display properties of both simple crystalline intermetallics and amorphous materials; e.g., it has a well-defined superconducting transition along with an exceptional robustness against disorder. Here we show that the valence electron count dependence of the superconducting transition temperature in the high-entropy alloy falls between those of analogous simple solid solutions and amorphous materials and test the effect of alloy complexity on the superconductivity. We propose high-entropy alloys as excellent intermediate systems for studying superconductivity as it evolves between crystalline and amorphous materials.

  9. Influence of creep damage on the low cycle thermal-mechanical fatigue behavior of two tantalum base alloys

    Science.gov (United States)

    Sheffler, K. D.; Doble, G. S.

    1972-01-01

    Low cycle fatigue tests have been performed on the tantalum base alloys T-111 and ASTAR 811C with synchronized, independently programmed temperature and strain cycling. The thermal-mechanical cycles applied fell into three basic categories: these were isothermal cycling, in-phase thermal cycling, and out-of-phase thermal cycling. In-phase cycling was defined as tensile deformation associated with high temperature and compressive deformation with low temperature, while out-of-phase thermal cycling was defined as the reverse case. The in-phase thermal cycling had a pronounced detrimental influence on the fatigue life of both alloys, with the life reduction being greater in the solid solution strengthened T-111 alloy than in the carbide strengthened ASTAR 811C alloy. The out-of-phase tests also showed pronounced effects on the fatigue life of both alloys, although not as dramatic.

  10. Alloy Design Challenge: Development of Low Density Superalloys for Turbine Blade Applications

    Science.gov (United States)

    MacKay, Rebecca A.; Gabb, Timothy P.; Smialek, James L.; Nathal, Michael V.

    2009-01-01

    New low density single crystal (LDS) alloys have been developed for turbine blade applications, which have the potential for significant improvements in the thrust to weight ratio over current production alloys. An innovative alloying strategy was identified to achieve high temperature creep resistance, alloy density reductions, microstructural stability, and cyclic oxidation resistance. The approach relies on the use of molybdenum (Mo) as a potent solid solution strengthener for the nickel (Ni)-base superalloy; Mo has a density much closer to Ni than other refractory elements, such as rhenium (Re) or tungsten (W). A host of testing and microstructural examinations was conducted on the superalloy single crystals, including creep rupture testing, microstructural stability, cyclic oxidation, and hot corrosion. The paper will provide an overview of the single crystal properties that were generated in this new superalloy design space. The paper will also demonstrate the feasibility of this innovative approach of low density single crystal superalloy design. It will be shown that the best LDS alloy possesses the best attributes of three generations of single crystal alloys: the low density of first-generation single crystal alloys, the excellent oxidation resistance of second-generation single crystal alloys, and a creep strength which exceeds that of second and third generation alloys.

  11. Fabrication of Heterogeneous-Phase Solid-Solution Promoting Band Structure and Charge Separation for Enhancing Photocatalytic CO2Reduction: A Case of ZnXCa1-XIn2S4.

    Science.gov (United States)

    Zeng, Chao; Huang, Hongwei; Zhang, Tierui; Dong, Fan; Zhang, Yihe; Hu, Yingmo

    2017-08-23

    Photocatalytic CO 2 reduction into solar fuels illustrates huge charm for simultaneously settling energy and environmental issues. The photoreduction ability of a semiconductor is closely correlated to its conduction band (CB) position. A homogeneous-phase solid-solution with the same crystal system always has a monotonously changed CB position, and the high CB level has to be sacrificed to achieve a benign photoabsorption. Herein, we report the fabrication of heterogeneous-phase solid-solution Zn X Ca 1-X In 2 S 4 between trigonal ZnIn 2 S 4 and cubic CaIn 2 S 4 . The Zn X Ca 1-X In 2 S 4 solid solutions with orderly tuned photoresponsive range from 540 to 640 nm present a more negative CB level and highly enhanced charge-separation efficiency. Profiting from these merits, all of these Zn X Ca 1-X In 2 S 4 solid solutions exhibit remarkably strengthened photocatalytic CO 2 reduction performance under visible light (λ > 420 nm) irradiation. Zn 0.4 Ca 0.6 In 2 S 4 , bearing the most negative CB position and highest charge-separation efficiency, casts the optimal photocatalytic CH 4 and CO evolution rates, which reach 16.7 and 6.8 times higher than that of ZnIn 2 S 4 and 7.2 and 3.9 times higher than that of CaIn 2 S 4 , respectively. To verify the crucial role of the heterogeneous-phase solid solution in promoting the band structure and photocatalytic performance, another heterogeneous-phase solid-solution Zn X Cd 1-X In 2 S 4 has been synthesized. It also displays an upshifted CB level and promoted charge separation. This work may provide a new perspective into the development of an efficient visible-light driven photocatalyst for CO 2 reduction and other photoreduction reactions.

  12. A Novel Cu-10Zn-1.5Ni-0.34Si Alloy with Excellent Mechanical Property Through Precipitation Hardening

    Science.gov (United States)

    Chen, Wei; Wang, Mingpu; Li, Zhou; Dong, Qiyi; Jia, Yanlin; Xiao, Zhu; Zhang, Rui; Yu, Hongchun

    2016-11-01

    A novel Cu-10Zn-1.5Ni-0.34Si alloy was designed to replace the expensive tin-phosphor bronze in this paper. The alloy had better comprehensive mechanical properties than traditional C5191 alloy. The aged Cu-10Zn-1.5Ni-0.34Si alloy had a hardness of 220 HV, electrical conductivity of 28.5% IACS, tensile strength of 650 MPa, yield strength of 575 MPa and elongation of 13%. Ni2Si precipitates formed during aging, and the crystal orientation relationship between matrix and precipitates was: (001)α//(001)δ, and [110]α//[100]δ. Ductile fracture surface with deep cavities was found in the alloy. Solid solution strengthening, deformation strengthening and precipitation strengthening were found to be core strengthening mechanisms in the alloy.

  13. Microstructural evolution and creep of Fe-Al-Ta alloys

    Energy Technology Data Exchange (ETDEWEB)

    Prokopcakova, Petra; Svec, Martin [Technical University of Liberec (Czech Republic). Dept. of Material Science; Palm, Martin [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany). Structure and Nano-/Micromechanics of Materials

    2016-05-15

    The microstructural evolution in Fe-Al-Ta alloys containing 23 - 31 at.% Al and 1.5 - 2.2 at.% Ta has been studied in the temperature range 650 - 750 C by annealing for 1, 10, 100 and 1 000 h. The experiments confirm that in this temperature range the precipitation of the stable hexagonal C14 Laves phase is preceded by formation of coherent, metastable L2{sub 1} Heusler phase precipitates within the Fe-Al matrix. However, precipitates of C14 are observed after much shorter annealing times than previously assumed. Creep strength increases substantially with increasing Al content of the alloys because the solid solubility for Ta in the Fe-Al matrix increases with increasing Al content and solid-solution hardening contributes substantially to the observed high creep strength. It may therefore be that the microstructural changes during creep have no noticeable effect on creep strength.

  14. Geochemical and numerical modelling of interactions between solid solutions and an aqueous solution. Extension of a reactive transport computer code called Archimede and application to reservoirs diagenesis; Modelisation geochimique et numerique des interactions entre des solutions solides et une solution aqueuse: extension du logiciel de reaction-transport archimede et application a la diagenese des reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Nourtier-Mazauric, E.

    2003-03-15

    This thesis presents a thermodynamic and kinetic model of interactions between a fluid and ideal solid solutions represented by several end-members. The reaction between a solid solution and the aqueous solution results from the competition between the stoichiometric dissolution of the initial solid solution and the co-precipitation of the least soluble solid solution in the fluid at considered time. This model was implemented in ARCHIMEDE, a computer code of reactive transport in porous media, then applied to various examples. In the case of binary solid solutions, a graphical method allowed to determine the compositions of the precipitating solid solutions, with the aid of the end-member chemical potentials. The obtained program could be used to notably model the diagenesis of clayey or carbonated oil reservoirs, or the ground pollutant dispersion. (author)

  15. Phase stability and elastic properties of Cr-V alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gao, M C; Suzuki, Y; Schweiger, H; Doğan, Ö N; Hawk, J; Widom, M

    2013-01-23

    V is the only element in the periodic table that forms a complete solid solution with Cr and thus is particularly important in alloying strategy to ductilize Cr. This study combines first-principles density functional theory calculations and experiments to investigate the phase stability and elastic properties of Cr–V binary alloys. The cluster expansion study reveals the formation of various ordered compounds at low temperatures that were not previously known. These compounds become unstable due to the configurational entropy of bcc solid solution as the temperature is increased. The elastic constants of ordered and disordered compounds are calculated at both T = 0 K and finite temperatures. The overall trends in elastic properties are in agreement with measurements using the resonant ultrasound spectroscopy method. The calculations predict that addition of V to Cr decreases both the bulk modulus and the shear modulus, and enhances the Poisson’s ratio, in agreement with experiments. Decrease in the bulk modulus is correlated to decrease in the valence electron density and increase in the lattice constant. An enhanced Poisson’s ratio for bcc Cr–V alloys (compared to pure Cr) is associated with an increased density of states at the Fermi level. Furthermore, the difference charge density in the bonding region in the (110) slip plane is highest for pure Cr and decreases gradually as V is added. The present calculation also predicts a negative Cauchy pressure for pure Cr, and it becomes positive upon alloying with V. The intrinsic ductilizing effect from V may contribute, at least partially, to the experimentally observed ductilizing phenomenon in the literature.

  16. Clean Grain Boundary Found in C14/Body-Center-Cubic Multi-Phase Metal Hydride Alloys

    Directory of Open Access Journals (Sweden)

    Hao-Ting Shen

    2016-06-01

    Full Text Available The grain boundaries of three Laves phase-related body-center-cubic (bcc solid-solution, metal hydride (MH alloys with different phase abundances were closely examined by scanning electron microscopy (SEM, transmission electron microscopy (TEM, and more importantly, electron backscatter diffraction (EBSD techniques. By using EBSD, we were able to identify the alignment of the crystallographic orientations of the three major phases in the alloys (C14, bcc, and B2 structures. This finding confirms the presence of crystallographically sharp interfaces between neighboring phases, which is a basic assumption for synergetic effects in a multi-phase MH system.

  17. Hg sub 2x (CuIn) sub 1-x Se sub 2 alloys: phase diagram and lattice parameter values

    Energy Technology Data Exchange (ETDEWEB)

    Grima Gallardo, P. (Physique des Milieux Condenses, Univ. Pierre et Marie Curie, 75 - Paris (France))

    1992-03-16

    Polycrystalline samples of Hg{sub 2x}(CuIn){sub 1-x}Se{sub 2} alloys are prepared by the melt and anneal technique. Differential thermal analysis (DTA) measurements are carried out on the alloys and the T(x) diagram is determined. Debye-Scherrer X-ray photographs are used to determine equilibrium conditions and lattice parameter values. It is found that single phase solid solutions occur at all values of composition. Experimental data for the chalcopyrite-zincblende transition temperature line are compared with an extension of Rincon's model for the order-disorder transition temperature in chalcopyrites. The agreement is notable. (orig.).

  18. Thermally driven metastable solid-solution Li0.5FePO4 in nanosized particles and its phase separation behaviors

    Science.gov (United States)

    Yoo, Sunyoung; Kang, Byoungwoo

    2013-10-01

    Nanosized LiFePO4 particles easily show a fast electrochemical response that can be achieved via a non-equilibrium pathway. To understand this intriguing phase transition behavior in nanosized LiFePO4 particles, the metastable solid-solution phase was prepared by thermal treatment with a chemically delithiated nanosized Li0.5FePO4 sample. Thermal treatment makes all the nanosized particles transform easily to the metastable solid-solution phase because of the large thermal energy while an electrochemical reaction does not. The phase separation behavior of the metastable solid-solution sample (Li0.5FePO4) was investigated under various kinetic conditions to understand critical factors affecting the phase separation behavior of nanosized LiFePO4 particles. The main findings in this study are as follows. The first finding is that the depressed phase separation behavior of the metastable phase may originate from the nanoparticle effect, in which the formation of a second phase inside a nanosized particle is not energetically favored because of the large interfacial energy. Therefore, phase separation in nanosized particles occurs between particles rather than inside a particle. If there was no over-potential, such as in the relaxed pellet experiment or in the relaxed electrode experiment in the electrolyte, the metastable phase was quite stable showing no phase separation behavior even though efficient pathways for lithium ions and electrons were well developed. The second finding is that the phase separation behavior of the metastable phase actually depends on the over-potential. Under open circuit voltage (OCV) conditions, the metastable phase started to exhibit a slight structural change during a long relaxation time, about ten days. The slow change of the metastable phase may be due to the low driving force, less than 10 mV, which comes from the energetic difference between the two-phase state and the metastable phase. This indicates that the phase separation

  19. Crystalline structure of the manganites solid solution RE(Me,MnO3, (RE=Gd,Er; Me=Ni,Co

    Directory of Open Access Journals (Sweden)

    Peña, O.

    2009-08-01

    Full Text Available The structural properties of the manganites solid solution RE(Me,MnO3, RE=Er,Gd, have been studied by X-ray diffraction and electric measurements. Powders were prepared by solid state reaction between the component oxides. Incorporation of Ni2+ or Co2+ on the lattice in the Mn sites leads to changes in the parameters and symmetry of the perovskite or hexagonal compounds GdMnO3 and ErMnO3 respectively. The phase transitions depend on the amount of substituted Jahn-Teller Mn3+ cations, and, therefore, of the cooperative Jahn-Teller interaction weakness. Solid solutions based on GdMnO3 perovskite compound change from O’-type to O-type orthorhombic perovskite symmetry when the Mn3+ cation amount decreases, because of the progressive substitution for Ni, Co. This transition occurs for lower amount of Ni2+ than for Co2+ cation. The Er-based solid solutions showed a different behaviour. For Ni2+ and Co2+ incorporation there are changes from hexagonal ErMnO3-type lattice to perovskite-type symmetry, for 20 at% and 30 at% respectively of substituting cations. The resultant perovskites crystallised directly in the O-type orthorhombic perovskite structure. The steric influence seems to play a secondary role, such as it can be deduced of the small variation of the Goldschmidt tolerance factor, t, for perovskite structure.

    Las propiedades estructurales de las soluciones sólidas RE(Me,MnO3, RE=Gd,Er, Me=Ni,Co, han sido estudiadas por difracción de rayos X, (DRX y medidas eléctricas. Las fases se sintetizaron por reacción en estado sólido entre los óxidos componentes. La incorporación de los cationes Ni2+ y Co2+,3+ en la red en lugar de Mn lleva a cambios en los parámetros de red y en la simetría de la perovskita, GdMnO3 o del compuesto hexagonal Er

  20. Corrosion behaviour of Al-Fe-Ti-V medium entropy alloy

    Science.gov (United States)

    Bodunrin, M. O.; Obadele, B. A.; Chown, L. H.; Olubambi, P. A.

    2017-12-01

    Alloys containing up to four multi-principal elements in equiatomic ratios are referred to as medium entropy alloys (MEA). These alloys have attracted the interest of many researchers due to the superior mechanical properties it offers over the traditional alloys. The design approach of MEA often results to simple solid solution with either body centered cubic; face centered cubic structures or both. As the consideration for introducing the alloys into several engineering application increases, there have been efforts to study the corrosion behaviour of these alloys. Previous reports have shown that some of these alloys are more susceptible to corrosion when compared with traditional alloys due to lack of protective passive film. In this research, we have developed AlFeTiV medium entropy alloys containing two elements (Ti and Al) that readily passivate when exposed to corrosive solutions. The alloys were produced in vacuum arc furnace purged with high purity argon. Open circuit potential and potentiodynamic polarisation tests were used to evaluate the corrosion behaviour of the as-cast AlFeTiV alloy in 3.5 wt% NaCl and 1 M H2SO4. The corrosion performance of the alloy was compared with Ti-6Al-4V alloy tested under similar conditions. The results show that unlike in Ti-6Al-4V alloy, the open circuit potential of the AlFeTiV alloy move towards the negative values in both 3.5 wt% NaCl and 1 M H2SO4 solutions indicating that self-activation occurred rapidly on immersion. Anodic polarisation of the alloys showed that AlFeTiV alloy exhibited a narrow range of passivity in both solutions. In addition, the alloys exhibited lower Ecorr and higher Icorr when compared with traditional Ti-6Al-4V alloy. The traditional Ti-6Al-4V alloy showed superior corrosion resistant to the AlFeTiV alloy in both 3.5 wt.% NaCl and 1 M H2SO4 solutions.

  1. Solid-solution partitioning and thionation of diphenylarsinic acid in a flooded soil under the impact of sulfate and iron reduction

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Meng [Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Tu, Chen [Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China); Hu, Xuefeng; Zhang, Haibo [Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Lijuan [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Wei, Jing [Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China); Li, Yuan [Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Luo, Yongming, E-mail: ymluo@yic.ac.cn [Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China); Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Christie, Peter [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China)

    2016-11-01

    Diphenylarsinic acid (DPAA) is a major organic arsenic (As) compound derived from abandoned chemical weapons. The solid-solution partitioning and transformation of DPAA in flooded soils are poorly understood but are of great concern. The identification of the mechanisms responsible for the mobilization and transformation of DPAA may help to develop effective remediation strategies. Here, soil and Fe mineral incubation experiments were carried out to elucidate the partitioning and transformation of DPAA in anoxic (without addition of sulfate or sodium lactate) and sulfide (with the addition of sulfate and sodium lactate) soil and to examine the impact of sulfate and Fe(III) reduction on these processes. Results show that DPAA was more effectively mobilized and thionated in sulfide soil than in anoxic soil. At the initial incubation stages (0–4 weeks), 6.7–74.5% of the total DPAA in sulfide soil was mobilized likely by sorption competition with sodium lactate. At later incubation stage (4–8 weeks), DPAA was almost completely released into the solution likely due to the near-complete Fe(III) reduction. Scanning transmission X-ray microscopy (STXM) results provide further direct evidence of elevated DPAA release coupled with Fe(III) reduction in sulfide environments. The total DPAA fraction decreased significantly to 24.5% after two weeks and reached 3.4% after eight weeks in sulfide soil, whereas no obvious elimination of DPAA occurred in anoxic soil at the initial two weeks and the total DPAA fraction decreased to 10.9% after eight weeks. This can be explained in part by the enhanced mobilization of DPAA and sulfate reduction in sulfide soil compared with anoxic soil. These results suggest that under flooded soil conditions, Fe(III) and sulfate reduction significantly promote DPAA mobilization and thionation, respectively, and we suggest that it is essential to consider both sulfate and Fe(III) reduction to further our understanding of the environmental fate of

  2. Structures, electron density and characterization of novel photocatalysts, (BaTaO2N)1-x(SrWO2N)x solid solutions.

    Science.gov (United States)

    Hibino, Keisuke; Yashima, Masatomo; Oshima, Takayoshi; Fujii, Kotaro; Maeda, Kazuhiko

    2017-10-18

    Tungsten-modified barium tantalum oxynitride is a new visible-light photocatalyst for water oxidation. In the present work, novel barium tantalum strontium tungsten oxynitride solid solutions, (BaTaO2N)1-x(SrWO2N)x, with a cubic Pm3[combining macron]m perovskite-type structure (x = 0.01 and 0.02) have been prepared by heating oxide precursors under an ammonia flow. These (BaTaO2N)1-x(SrWO2N)x catalysts exhibited photocatalytic water oxidation activity under visible light irradiation. The crystal structure, electron-density distribution, and optical properties of (BaTaO2N)1-x(SrWO2N)x (x = 0, 0.01, and 0.02) have been studied using synchrotron X-ray powder diffraction, Rietveld analysis, the maximum-entropy method (MEM), and UV-Vis reflectance measurements. The lattice parameters of (BaTaO2N)1-x(SrWO2N)x decreased linearly with increasing SrWO2N content x. The minimum electron density (MED) at the (Ta,W)-(O,N) bond, determined by the MEM analysis of (BaTaO2N)1-x(SrWO2N)x, increased with x, as supported by DFT-based calculations. These results indicate the formation of (BaTaO2N)1-x(SrWO2N)x solid solutions and enhanced covalent bonding due to the stronger W-N bond. The MED of the (Ta,W)-(O,N) bond was higher than that of (Ba,Sr)-(O,N), indicating that the (Ta,W)-(O,N) bond is more covalent. The presence of nitrogen in (BaTaO2N)1-x(SrWO2N)x was confirmed by the occupancy factor refined using neutron diffraction data and by the weight gain observed by thermogravimetric analysis in air. UV-Vis reflectance spectra and DFT calculations indicated that (BaTaO2N)1-x(SrWO2N)x contains W(5+) cations with a [Xe] 4f(14) 5d(1) electron configuration and exhibits a more n-type semiconducting character compared with BaTaO2N, which could improve the photocatalytic water oxidation activity under visible-light irradiation.

  3. Facile synthesis and photocatalytic properties of ZnO core/ZnS-CdS solid solution shell nanorods grown vertically on reductive graphene oxide.

    Science.gov (United States)

    Xu, Jimeng; Sang, Huanxin; Wang, Xitao; Wang, Kang

    2015-05-28

    In the present study, ZnS-CdS solid solution sensitized ZnO nanorods were anchored on graphene sheets by combining a hydrothermal process and ion exchange technique, and the significant influence of CdS content in the shell on photo absorption and photocatalytic performance were investigated. Electron microscopic images reveal that the as-prepared nanocomposites display a sandwich-like 3D structure, consisting of ZnO nanorods with a ZnxCd1-xS or CdS shell grown vertically on both sides of the graphene sheets. UV/Vis DRS shows that the solid solution sensitized nanocomposites have enhanced visible light absorption and also exhibited a red-shift of the band-edge as compared to RGO/ZnO and RGO/ZnO@ZnS. Fluorescence emission spectra indicate that the deposition of CdS on the shell with an appropriate CdS/ZnS ratio and the incorporation of graphene causes improved charge separation. The photocatalytic experiments demonstrate that the RGO/ZnO@ZnxCd1-xS nanocomposites possess much higher photocatalytic activity for H2 evolution than the RGO/ZnO nanorods and RGO/ZnO@ZnS core/shell nanorods. Under the irradiation of a 300 W Xe lamp, the highest photocatalytic hydrogen production rate of 1865 μmol h(-1) g(-1) is observed over the RGO/ZnO@Zn0.6Zn0.4S sample, which is about 2.1 and 1.4 times more active than RGO/ZnO and RGO/ZnO@ZnS, respectively. Under the irradiation of visible light (>420 nm), the RGO/ZnO and RGO/ZnO@ZnS nanorods are barely active, whereas RGO/ZnO@Zn0.6Zn0.4S displays a hydrogen production rate of 160 μmol h(-1) g(-1). The highly improved performance of the composites can be ascribed to the increased light absorption and efficient charge separation.

  4. Nanostructured gadolinium-doped ceria microsphere synthesis from ion exchange resin: Multi-scale in-situ studies of solid solution formation

    Energy Technology Data Exchange (ETDEWEB)

    Caisso, Marie [CEA, DEN, DTEC/SDTC/LEMA, F-30207 Bagnols-sur-Cèze Cedex (France); Institut Européen des Membranes, UMR 5635 CNRS-ENSCM-UM2, CC047, Université Montpellier 2, F-34095 Montpellier Cedex 5 (France); Lebreton, Florent; Horlait, Denis [CEA, DEN, DTEC/SDTC/LEMA, F-30207 Bagnols-sur-Cèze Cedex (France); Picart, Sébastien [CEA, DEN, DRCP/SERA/LCAR, F-30207 Bagnols-sur-Cèze Cedex (France); Martin, Philippe M.; Bès, René [CEA, DEN, DEC/SESC/LLCC, F-13108 Saint-Paul-Lez-Durance Cedex (France); Renard, Catherine; Roussel, Pascal [Unité de Catalyse et Chimie du Solide, UMR 8012 CNRS, Ecole Nationale Supérieure de Chimie de Lille BP 90108, 59652 Villeneuve d’Ascq Cedex (France); Neuville, Daniel R. [Institut de Physique du Globe de Paris-CNRS, Géochimie and Cosmochimie, 1 rue Jussieu, 75005 Paris (France); Dardenne, Kathy; Rothe, Jörg [Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal (KIT-INE), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Delahaye, Thibaud, E-mail: thibaud.delahaye@cea.fr [CEA, DEN, DTEC/SDTC/LEMA, F-30207 Bagnols-sur-Cèze Cedex (France); Ayral, André [Institut Européen des Membranes, UMR 5635 CNRS-ENSCM-UM2, CC047, Université Montpellier 2, F-34095 Montpellier Cedex 5 (France)

    2014-10-15

    In the current nano-sized material revolution, the main limitations to a large-scale deployment of nanomaterials involve health concerns related to nano-dissemination via air. Developing new chemical routes benefiting from nano-size advantages while avoiding their hazards could overcome these limitations. Addressing this need, a chemical route leading to soft nano-particle agglomerates, i.e., macroscopic precursors presenting the ability to be decomposed into nano-sized materials, was developed and applied to Ce{sub 0.8}Gd{sub 0.2}O{sub 2−δ}. Using cerium/gadolinium-loaded ion exchange resin, the Ce{sub 0.8}Gd{sub 0.2}O{sub 2−δ} solid solution formation as a function of temperature was studied in-situ through X-ray diffraction, X-ray absorption spectroscopy and Raman spectroscopy. Temperatures corresponding to the organic skeleton decomposition and to the mixed oxide crystallization were identified. An optimal heat treatment, leading to nanostructured soft agglomerates, was established. Microsphere processing capabilities were evaluated and particle size distribution measurements were recorded. A very low fracture strength was calculated, and a nanometric particle size distribution (170 nm) was determined. - Graphical abstract: The elaboration of micro-spherical precursors leading to the formation of nano-oxide soft agglomerates was studied and approved through the use of ion exchange resin loaded with cerium and gadolinium. The formation of the solid solution was followed through in-situ measurements such as XAS, XRD, Raman, TGA and DSC. Key temperatures were identified for the formation of the mixed-oxide. Following this study, the microstructure and particle size of oxide microspheres formed highlight the formation of soft nano-arrangments. - Highlights: • Soft microspherical agglomerates able to be decomposed into nano-sized materials. • In situ study of cerium/gadolinium-loaded ion exchange resin conversion in oxide. • In situ multi-scale study

  5. High temperature strain of metals and alloys. Physical fundamentals

    Energy Technology Data Exchange (ETDEWEB)

    Levitin, V. [National Technical Univ., Zaporozhye (Ukraine)

    2006-07-01

    The author shows how new in-situ X-ray investigations and transmission electron microscope studies lead to novel explanations of high-temperature deformation and creep in pure metals, solid solutions and super alloys. This approach is the first to find unequivocal and quantitative expressions for the macroscopic deformation rate by means of three groups of parameters: substructural characteristics, physical material constants and external conditions. Creep strength of the studied uptodate single crystal super alloys is greatly increased over conventional polycrystalline super alloys. The contents of this book include: macroscopic characteristics of strain at high temperatures; experimental equipment and technique of in situ X-ray investigations; experimental data and structural parameters in deformed metals; sub-boundaries as dislocation sources and obstacles; the physical mechanism of creep and the quantitative structural model; simulation of the parameters evolution; system of differential equations; high-temperature deformation of industrial super alloys; single crystals of super alloys; effect of composition, orientation and temperature on properties; and creep of some refractory metals.

  6. Precipitation hardening of biodegradable Fe-Mn-Pd alloys

    Energy Technology Data Exchange (ETDEWEB)

    Moszner, F. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Sologubenko, A.S. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Laboratory for Nanometallurgy, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Schinhammer, M. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Lerchbacher, C. [Christian Doppler Laboratory for Early Stages of Precipitation, University of Leoben, Franz-Josef-Strasse 18, 8700 Leoben (Austria); Haenzi, A.C. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Leitner, H. [Christian Doppler Laboratory for Early Stages of Precipitation, University of Leoben, Franz-Josef-Strasse 18, 8700 Leoben (Austria); Uggowitzer, P.J. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Loeffler, J.F., E-mail: joerg.loeffler@mat.ethz.ch [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland)

    2011-02-15

    This work presents a phenomenological description of the precipitation controlled hardening of a new biodegradable Fe-based alloy developed to fulfill the requirements of temporary implant applications. Pronounced strengthening of the solution-treated martensitic Fe-10Mn-1Pd (in wt.%) alloy upon isothermal aging at temperatures within the ferrite-austenite phase field is observed and attributed to the thermally activated formation of coherent plate-like Pd-rich precipitates on {l_brace}1 0 0{r_brace} planes of the matrix. The onset and the early stages of alloy decomposition were studied using two complementary techniques: transmission electron microscopy and three-dimensional atom probe analysis. Three distinct regions of the hardening kinetics are recognized and closely correlated to the evolution of the alloy microstructure. Upon aging, clustering of Pd atoms within the Fe-Mn solid solution occurs. The very small clusters grow, coarsen and adopt a plate-like shape, rearranging mutually to reduce the overall elastic strain energy. The elastic interaction of the dislocation substructure with Pd-rich precipitates of evolving morphology affects the dislocation mobility and is responsible for the hardness evolution of the alloy. A study of the hardening kinetics shows that the process exhibits all the features characteristic of maraging steels.

  7. Effect of cooling rate on the phase structure and magnetic properties of Fe{sub 26.7}Co{sub 28.5}Ni{sub 28.5}Si{sub 4.6}B{sub 8.7}P{sub 3} high entropy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Ran; Sun, Huan; Chen, Chen [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); Han, Zhenhua [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710068 (China); Li, Fushan, E-mail: fsli@zzu.edu.cn [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China)

    2017-08-01

    Highlights: • High entropy alloy with amorphous phase and FCC solid solution phase are successfully developed respectively. • The amorphous phase exhibits better soft magnetic properties than that of the solid solution phase. • The BCC phase transformed into FCC phase, and then into BCC phase was found in this HEA. - Abstract: The effect of cooling rate on phase structure and magnetic properties of the Fe{sub 26.7}Co{sub 28.5}Ni{sub 28.5}Si{sub 4.6}B{sub 8.7}P{sub 3} high entropy alloy (HEA) was investigated. The HEA forms into amorphous phase by melt spinning method at high cooling rate and FCC solid solution phase at low cooling rate. The soft magnetic properties of the amorphous phase (saturation magnetization B{sub s} of 1.07T and coercivity H{sub c} of 4 A/m) are better than that of the solid solution phase (B{sub s} of 1.0 T and H{sub c} of 168 A/m). In order to study the phase evolution of the present HEA, anneal experiments were conducted. It is found that crystallization products of amorphous phase are solid solution phase which constitute much of FCC and a small amount of BCC. BCC phase transforms into FCC phase, and then into BCC phase with the increase of annealing temperature.

  8. Ab Initio Predicted Alloying Effects on the Elastic Properties of AlxHf1−xNbTaTiZr High Entropy Alloys

    Directory of Open Access Journals (Sweden)

    Shaohui Li

    2015-07-01

    Full Text Available Using ab initio alloy theory, we investigate the equilibrium bulk properties and elastic mechanics of the single bcc solid-solution AlxHf1−xNbTaTiZr (x = 0–0.7, 1.0 high entropy alloys. Ab initio predicted equilibrium volume is consistent with the available experiment. We make a detailed investigation of the alloying effect of Al and Hf on the equilibrium volume, elastic constants and polycrystalline elastic moduli. Results imply that the partial replacement Hf with Al increases the stability of the bcc phase and decreases the ductility of the AlxHf1−xNbTaTiZr HEAs. The inner ductility of Al0.4Hf0.6NbTaTiZr is predicted by the calculations of ideal tensile strength.

  9. BRAZING ALLOYS

    Science.gov (United States)

    Donnelly, R.G.; Gilliland, R.G.; Slaughter, G.M.

    1962-02-20

    A brazing alloy is described which, in the molten state, is characterized by excellent wettability and flowability and is capable of forming a corrosion-resistant brazed joint. At least one component of said joint is graphite and the other component is a corrosion-resistant refractory metal. The brazing alloy consists essentially of 40 to 90 wt % of gold, 5 to 35 wt% of nickel, and 1 to 45 wt% of tantalum. (AEC)

  10. Analysis of PTA hardfacing with CoCrWC and CoCrMoSi alloys

    Directory of Open Access Journals (Sweden)

    Adriano Scheid

    2013-12-01

    Full Text Available CoCrWC alloys are widely used to protect components that operate under wear and high temperature environments. Enhanced performance has been achieved with the CoCrMoSi alloys but processing this alloy system is still a challenge due to the presence of the brittle Laves phase, particularly when welding is involved. This work evaluated Plasma Transferred Arc coatings processed with the Co-based alloy CoMoCrSi - Tribaloy T400, reinforced with Laves phase, comparing its weldability to the CoCrWC - Stellite 6, reinforced with carbides. Coatings were also analyzed regarding the response to temperature exposure at 600°C for 7 days and subsequent effect on microstructure and sliding abrasive wear. Coatings characterization was carried out by light and scanning electron microscopy, X-ray diffraction and Vickers hardness. CoCrWC coatings exhibited a Cobalt solid solution dendritic microstructure and a thin interdendritic region with eutectic carbides, while CoCrMoSi deposits exhibit a large lamellar eutectic region of Laves phase and Cobalt solid solution and a small fraction of primary Laves phase. Although phase stability was observed by X-ray diffraction, coarsening of the microstructure occurred for both alloys. CoCrMoSi showed thicker lamellar Laves phase and CoCrWC coarser eutectic carbides. Coatings stability assessed by wear tests revealed that although the wear rate of the as-deposited CoCrMoSi alloy was lower than that of CoCrWC alloy its increase after temperature exposure was more significant, 22% against 15%. Results were discussed regarding the protection of industrial components in particular, bearings in 55AlZn hot dip galvanizing components.

  11. A simple template-free synthesis of nanoporous ZnS-In2S3-Ag2S solid solutions for highly efficient photocatalytic H2 evolution under visible light.

    Science.gov (United States)

    Li, Yingxuan; Chen, Gang; Zhou, Chao; Sun, Jingxue

    2009-04-21

    Nanoporous ZnS-In(2)S(3)-Ag(2)S solid solutions synthesized by a facile template-free method showed relatively high activities for photocatalytic H(2) evolution under visible-light irradiation (lambda >400 nm) even in the absence of co-catalysts.

  12. Structure and Charge Density Properties of (1 - x)(Na1- y K y NbO3)- xBaTiO3 Lead-Free Ceramic Solid Solution

    Science.gov (United States)

    Sasikumar, S.; Saravanan, R.

    2017-07-01

    (1 - x)(Na1- y K y )NbO3- xBaTiO3 (abbreviated as NKN-BT, x = 0.1, 0.2; y = 0.01, 0.05) ceramics were synthesized by the solid-state reaction method. Powder x-ray diffraction analysis in combination with the profile refinement method was employed for quantitative phase analysis and structural refinement. The x-ray diffraction study shows that phase transition occurs from tetragonal to distorted cubic with the compositions between x = 0.1 and x = 0.2. The spatial arrangements of the electron distribution and bonding nature of the samples have been analyzed through the maximum entropy method. The optical band gap energy of the prepared solid solutions has been determined using UV-visible spectrophotometry. The optical band gap energy of the solid solutions decreases with the increase in BaTiO3 content. The elemental composition of these ceramics has been studied using energy dispersive x-ray analysis and the microstructure has been examined by scanning electron microscopy. The piezoelectric coefficient ( d 33 ) measurement of the ceramics shows the enhancement of piezoelectric properties in the tetragonal phase. The maximum value of the piezoelectric coefficient ( d 33 ) obtained for the solid solution is 120 pC/N. With increasing BaTiO3 content in the solid solutions, the ferroelectric behavior weakens.

  13. On the ‘centre of gravity’ method for measuring the composition of magnetite/maghemite mixtures, or the stoichiometry of magnetite-maghemite solid solutions, via 57Fe Mössbauer spectroscopy

    DEFF Research Database (Denmark)

    Fock, Jeppe; Bogart, Lara K.; González-Alonso, David

    2017-01-01

    spectrum, and is correlated to the sample’s composition or stoichiometry. We present data on high-purity magnetite and maghemite powders, and mixtures thereof, as well as comparison literature data from nanoparticulate mixtures and solid solutions, to show that a linear correlation exists between δ̅RT...

  14. An X-ray absorption spectroscopy investigation of the local atomic structure in Cu-Ni-Si alloy after severe plastic deformation and ageing

    Science.gov (United States)

    Azzeddine, H.; Harfouche, M.; Hennet, L.; Thiaudiere, D.; Kawasaki, M.; Bradai, D.; Langdon, T. G.

    2015-08-01

    The local atomic structure of Cu-Ni-Si alloy after severe plastic deformation (SPD) processing and the decomposition of supersaturated solid solution upon annealing were investigated by means of X-ray absorption spectroscopy. The coordination number and interatomic distances were obtained by analyzing experimental extend X-ray absorption fine structure data collected at the Ni K-edge. Results indicate that the environment of Ni atoms in Cu-Ni-Si alloy is strongly influenced by the deformation process. Moreover, ageing at 973 K affects strongly the atomic structure around the Ni atoms in Cu-Ni-Si deformed by equal channel angular pressing and high pressure torsion. This influence is discussed in terms of changes and decomposition features of the Cu-Ni-Si solid solution.

  15. Effect of Indium Content on the Microstructure, Mechanical Properties and Corrosion Behavior of Titanium Alloys

    Directory of Open Access Journals (Sweden)

    Mi-Kyung Han

    2015-05-01

    Full Text Available Ti-xIn (x = 0, 5, 10, 15 and 20 wt% alloys were prepared to investigate the effect of indium on the microstructure, mechanical properties, and corrosion behavior of titanium with the aim of understanding the relationship between phase/microstructure and various properties of Ti-xIn alloys. The Ti-xIn alloys exhibited a lamellar α-Ti structure at an indium content of up to 20 wt%. High-resolution TEM images of the Ti-xIn alloys revealed that all the systems contained a fine, acicular martensitic phase, which showed compositional fluctuations at the nanoscopic level. The mechanical properties and corrosion behavior of Ti-xIn alloys were sensitive to the indium content. The Vickers hardness increased as the In content increased because of solid solution strengthening. The Ti-xIn alloys exhibited superior oxidation resistance compared to commercially pure Ti (cp-Ti. Electrochemical results showed that the Ti-xIn alloys exhibited a similar corrosion resistance to cp-Ti. Among the alloys tested, Ti-10In showed a potential for use as a dental material.

  16. Evaluation of lithium alloy anode materials for Li-TiS2 cells

    Science.gov (United States)

    Huang, C.-K.; Subbarao, S.; Shen, D. H.; Deligiannis, F.; Attia, A.; Halpert, G.

    1991-01-01

    A study was performed to select candidate lithium alloy anode materials and establish selection criteria. Some of the selected alloy materials were evaluated for their electrochemical properties and performance. This paper describes the criteria for the selection of alloys and the findings of the studies. Li-Si and Li-Cd alloys have been found to be unstable in the EC+2-MeTHF-based electrolyte. The Li-Al alloy system was found to be promising among the alloy systems studied in view of its stability and reversibility. Unfortunately, the large volume changes of LiAl alloys during charge/discharge cycling cause considerable 'exfoliation' of its active mass. This paper also describes ways how to address this problem. The rate of disintegration of this anode would probably be surpressed by the presence of an inert solid solution or a uniform distribution of precipitates within the grains of the active mass. It was discovered that the addition of a small quantity of Mn may improve the mechanical properties of LiAl. In an attempt to reduce the Li-Al alloy vs. Li voltage, it was observed that LiAlPb(0.1)Cd(0.3) material can be cycled at 1.5 mA/sq cm without exfoliation of the active mass.

  17. From Ag{sub 2}Sb{sub 2}O{sub 6} to Cd{sub 2}Sb{sub 2}O{sub 7}: Investigations on an anion-deficient to ideal pyrochlore solid solution

    Energy Technology Data Exchange (ETDEWEB)

    Laurita, Geneva [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States); Vielma, Jason [Department of Physics, Oregon State University, Corvallis, OR 97331 (United States); Winter, Florian [Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30, D-48149 Münster (Germany); Berthelot, Romain [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States); CNRS, Univ. Bordeaux, ICMCB, UPR9048, F-33600 Pessac (France); Largeteau, Alain [CNRS, Univ. Bordeaux, ICMCB, UPR9048, F-33600 Pessac (France); Pöttgen, Rainer [Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30, D-48149 Münster (Germany); Schneider, G. [Department of Physics, Oregon State University, Corvallis, OR 97331 (United States); Subramanian, M.A., E-mail: mas.subramanian@oregonstate.edu [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States)

    2014-02-15

    A complete solid solution between the anion-deficient pyrochlore Ag{sub 2}Sb{sub 2}O{sub 6} and the ideal pyrochlore Cd{sub 2}Sb{sub 2}O{sub 7} has been synthesized through the standard solid state ceramic method. Each composition has been characterized by various different techniques, including powder X-ray diffraction, optical spectroscopy, electron paramagnetic resonance and {sup 121}Sb Mössbauer spectroscopy. Computational methods based on density functional theory complement this investigation. Photocatalytic activity has been studied, and transport properties have been measured on pellets densified by spark plasma sintering. The analysis of the data collected from these various techniques enables a comprehensive characterization of the complete solid solution and revealed an anomalous behavior in the Cd-rich end of the solid solution, which has been proposed to arise from a possible radical O{sup −} species in small concentrations. - Graphical abstract: A complete solid solution between the anion-deficient pyrochlore Ag{sub 2}Sb{sub 2}O{sub 6} and the ideal pyrochlore Cd{sub 2}Sb{sub 2}O{sub 7} has been synthesized and investigated through various techniques including X-ray diffraction, electron paramagnetic spectroscopy, and {sup 121}Sb-Mössbauer spectroscopy. Optical and electrical measurements have been performed, and computational methods have been applied to determine the density of states. Photocatalytic activity was monitored by the degradation of Methylene Blue, and upon cadmium substitution, the degradation amount decreased, which is attributed primarily to the changing optical and electrical properties of the solid solution. Display Omitted - Highlights: • A complete solid solution between Ag{sub 2}Sb{sub 2}O{sub 6} and Cd{sub 2}Sb{sub 2}O{sub 7} has been synthesized. • XRD reveals a relatively constant lattice parameter as the series progresses. • Optical and electrical properties have been measured for the solid solution.

  18. Heterophase states and domain effects in solid solutions of (1 - x)BiFeO3 - xPbTiO3

    Science.gov (United States)

    Topolov, V. Yu.

    2012-05-01

    Examples of heterophase states in multiferroic solid solutions of (1 - x)BiFeO3 - xPbTiO3 with the perovskite-type structure are studied taking into account the features of elastic matching of polydomain (twinned) ferroelectric phases near the morphotropic phase boundary and in a wide temperature range. Conditions for the complete stress relief are examined in the heterophase states P4mm-P4mm and P4mm-Cc to interpret variations of the phase content [S. Bhattacharjee et al., Phys. Rev. B 84, 104116 (2011)] [S. Bhattacharjee and D. Pandey, J. Appl. Phys. 110, 084105 (2011)] in (1-x)BiFeO3-xPbTiO3. The key role of some 90° domain types of the low-temperature ferroelectric P4mm phase in the stress relief at the phase coexistence is emphasized. An agreement between the evaluated and experimental data on the volume fraction of the low-temperature P4mm phase in heterophase samples is observed.

  19. Perovskite solid solutions La0.75Bi0.25Fe1-xCrxO3: Preparation, structural, and magnetic properties

    Science.gov (United States)

    Ivanov, S. A.; Beran, P.; Bazuev, G.; Tellgren, R.; Sarkar, T.; Nordblad, P.; Mathieu, R.

    2017-10-01

    Solid solutions of La0.75Bi0.25Fe1-xCrxO3 (x = 0.1, 0.25, 0.5, and 0.75) prepared by conventional solid state reaction have been studied by means of X-ray powder diffraction (XRPD), neutron powder diffraction (NPD) and magnetic measurements. The NPD and XRPD patterns indicate orthorhombic structure (space group Pnma) for all compositions in the whole temperature range investigated (4-900 K). The lattice parameters of La0.75Bi0.25Fe1-xCrxO3 were found to decrease with the Cr content. It was established that the Fe3+ and Cr3+ cations are randomly positioned at the B-site of the perovskite structure. All samples order antiferromagnetically below transition temperatures that decrease with increasing Cr content, from around 700 K for x = 0.1 to about 300 K for x = 0.75. The antiferromagnetic arrangement of the Fe3+/Cr3+ magnetic moments in the B-site is of G-type along the x-axis (Gx mode) with propagation vector k = (0,0,0) for all concentrations of Cr. Effects of the composition on several structural distortion parameters were investigated and an anomalous variation of the octahedral deformation with Cr content was found. Whilst the overall octahedral deformation varies irregularly with increasing Cr content, the octahedral tilting was found to decrease monotoneously.

  20. Tsdc and Neutron-Scattering Measurements on Ba1-Xlaxf2+X and Ba1-Xuxf2+2x Solid-Solutions

    DEFF Research Database (Denmark)

    Ouwerkerk, M; Veldkamp, F. F.; Andersen, Niels Hessel

    1985-01-01

    A study was made of the dynamical behaviour of bound interstitial fluoride ions in disordered Ba1−xLaxF2+x and Ba1−xUxF2+2x solid solutions with Thermally Stimulated Depolarisation Current measurements and neutron scattering measurements, and a combination of both techniques. From 10 K to 400 K...... the TSDC spectra showed four reorientation peaks to be present in Ba1−xLaxF2+x, and six in Ba1−xUxF2+2x, along with the relaxation of the macroscopic space charge. The position of a space charge peak shifted to lower temperatures with increasing solute content. The dipolar realaxations were concentration...... invariant. In Ba1−xLaxF2+x neutral associates, L-shaped- and (222)- clusters occur. The present study reveals (212)-clusters to be present in Ba1−xUxF2+2x. The relations between ion dynamics and defect structures are discussed....

  1. The solid solution Sr3Ti2-xFexO7-δ (x ≤ 0.5: characterization of Fe (III – Fe (IV mixed valences

    Directory of Open Access Journals (Sweden)

    I. Zvereva

    2016-03-01

    Full Text Available The results of a magneto chemical and Mössbauer characterization are reported for the solid solution Sr3Ti2-xFexO7-δ (x ≤ 0.5, the intergrowth of a double perovskite block and one rock-salt layer type. The charge compensation mechanism induced by the introduction of iron atoms in the matrix of Sr3Ti2O7 is sensitive to the conditions of synthesis, namely an oxidation process triggers the formation of mixed Fe(III-Fe(IV valences. The crystallographic characterization - variation of the cell parameters and structure calculations – brings evidence for the respective occurrence of mixed valences and oxygen vacancies which form in the middle plane of the double perovskite block. Ferromagnetic exchange interactions which are absent in the Fe(III containing compositions, appear and progressively strengthen depending on the oxidizing treatment. They are ascribed to the presence of an increasing amount of Fe(IV species. Remarkably, a mixed valence state of iron forms during annealing in air with an increasing contribution of the Fe(IV species for the larger iron contents, as deduced from Mössbauer data.

  2. Mechanochemical synthesis, structure, and properties of solid solutions of alkaline earth metal fluorides: Ma1-xMbxF2 (M: Ca, Sr, Ba)

    Science.gov (United States)

    Heise, M.; Scholz, G.; Düvel, A.; Heitjans, P.; Kemnitz, E.

    2016-10-01

    The capability of mechanochemical synthesis for the formation of solid solutions of alkaline earth metal fluorides Ma1-xMbxF2 (M: Ca, Sr, Ba) was tested by fluorination of metal acetates and metal hydroxides with ammonium fluoride directly at milling. Evidence was found for a mutual substitution of cations on their lattice positions in Ca1-xSrxF2 and Ba1-xSrxF2 samples. For the Ba/Ca-system this synthesis route is only partially successful. X-ray diffraction and 19F MAS NMR spectroscopy were used to characterize all samples concerning their crystal structure and local fluorine coordination. Calculations of 19F chemical shifts with the superposition model along with probability calculations for the intensity of the individual 19F lines, performed in dependence on the molar composition of the samples, perfectly agree with the experimental findings. The fluoride ion conductivity of as-prepared samples, determined by temperature dependent DC conductivity measurements, is significantly higher than those of crystalline binary fluorides. Moreover, a higher F- ion conductivity is observed for samples with higher mixing grade in the Ca/Sr-and the Ba/Sr-systems.

  3. Structural disorder and transformation in crystal growth: direct observation of ring-opening isomerization in a metal–organic solid solution

    Directory of Open Access Journals (Sweden)

    Ji-Jun Jiang

    2014-09-01

    Full Text Available A rare example is reported in which discrete Ag2L2 ring and (AgL∞ chain motifs [L = N,N′-bis(3-imidazol-1-yl-propyl-pyromellitic diimide] co-crystallize in the same crystal lattice with varying ratios and degrees of disorder. Crystal structures obtained from representative crystals reveal compatible packing arrangements of the cyclic and polymeric isomers within the crystal lattice, which enables them to co-exist within a crystalline solid solution. A feasible pathway for transformation between the isomers is suggested via facile rotation of the coordinating imidazolyl groups. This chemical system could provide a chance for direct observation of ring-opening isomerization at the crystal surface. Mass spectrometry and 1H NMR titration show a dynamic equilibrium between cyclic and oligomeric species in solution, and a potential crystallization process is suggested involving alignment of precursors directed by aromatic stacking interactions between pyromellitic diimide units, followed by ring-opening isomerization at the interface between the solid and the solution. Both cyclic and oligomeric species can act as precursors, with interconversion between them being facile due to a low energy barrier for rotation of the imidazole rings. Thermogravimetric analysis and variable-temperature powder X-ray diffraction indicate a transition to a different crystalline phase around 120°C, which is associated with loss of solvent from the crystal lattice.

  4. Detailed investigation on structural, dielectric, magnetic and magnetodielectric properties of BiFeO3-BaSrTiO3 solid solutions

    Science.gov (United States)

    Pal, Jaswinder; Kumar, Sunil; Singh, Lakhwant; Singh, Mandeep; Singh, Anupinder

    2017-11-01

    Polycrystalline (1 - x) BiFeO3-xBa0.8Sr0.2TiO3 (0.1 ≤ x ≤ 0.9) ceramics have been synthesized by using the solid-state-reaction method. The structural, dielectric, ferroelectric, magnetic and electrical properties of the resulting solid solutions have been investigated. XRD analysis reveals that the composition-driven rhombohedral to cubic phase transition occurs at x ≈ 0.4. Experimental results reveal that BST substitution leads to the suppression of the spiral spin structure, resulting in the appearance of net magnetization. The electrical conductivity has been found to increase with increase in frequency of applied electric field. The dielectric constant (ε‧) and the dielectric loss (ε″) have been found to decrease with increase in frequency of applied electric field and shows non-Debye relaxation behavior. The samples have been found to exhibit magnetoelectric coupling (up to x = 0.2). An enhancement in ferroelectric properties with increasing BST content (up to x = 0.3) has been observed.

  5. Optical spectroscopy and magnetic behaviour of Sm3+ and Eu3+ cations in Li6Eu1-xSmx(BO3)3 solid solution

    Science.gov (United States)

    Belhoucif, Rekia; Velázquez, Matias; Plantevin, Olivier; Aschehoug, Patrick; Goldner, Philippe; Christian, George

    2017-11-01

    A new borate solid solution series of powders, Li6Eu1-xSmx(BO3)3 (LSEBx, x = 0.35, 0.5, 0.6, 1), were synthesized by solid-state reaction, characterized and their luminescent properties were investigated. The absorption spectra indicate that absorption takes place mainly from the Sm3+6H5/2 ground state, with a strong band at 405 nm. The photoluminescence spectra reveal that the Eu3+ red emission intensity strongly depends on the Sm3+ content x. Judd-Ofelt theory was applied to experimental data for the quantitative determination of phenomenological parameters Ωi (i = 2, 4, 6) Judd Ofelt parameters, radiative transition rates and emission quantum efficiency. Owing to the energy transfer from Sm3+ to Eu3+ the intense red light detected at 613 nm at room temperature under UV or blue light excitation, was improved by ∼35% as compared with Sm3+-free samples. This energy transfer was confirmed by faster decay times of Sm3+ as energy donors. Moreover, the energy transfer between Sm3+ and Eu3+ is unidirectional and irreversible, implying that the energy transfer wastage between Sm3+ and Eu3+ is very low. Magnetic susceptibility (χ) measurements of LSEBx were carried out in the temperature range 2-320 K and are used to compare calculated and experimental energy levels.

  6. Order-disorder transition and electrical conductivity of the brownmillerite solid-solutions system Ba sub 2 (In, M) sub 2 O sub 5 (M=Ga, Al)

    CERN Document Server

    Yamamura, H; Kakinuma, K; Mori, T; Haneda, H

    1999-01-01

    The brownmillerite solid-solution systems Ba sub 2 (In sub 1 sub - sub x M sub x) sub 2 O sub 5 (M=Ga, Al) were investigated by means of high-temperature X-ray diffraction (XRD), dilatometry, and electrical-conductivity measurements. XRD showed that the Ba sub 2 (In sub 1 sub - sub x Ga sub x) sub 2 O sub 5 system had orthorhombic symmetry in the composition range 0.0<=x<=0.2 and cubic symmetry in the range 0.3<=x. The Al system also changed to cubic symmetry from orthorhombic symmetry in the range 0.2<=x. While the orthorhombic phase showed an order-disorder transition in the electrical conductivity measurements, the transition temperature decreased with increasing the M content. The order-disorder transition temperature and the crystal-structure transition temperature were very different. Such a transition was not observed in the cubic phases, and their electrical conductivity were fairly low compared to those of the disordered cubic phase after the transition due to the heating process. These p...

  7. An artificial photosynthesis anode electrode composed of a nanoparticulate photocatalyst film in a visible light responsive GaN-ZnO solid solution system

    Science.gov (United States)

    Imanaka, Yoshihiko; Anazawa, Toshihisa; Manabe, Toshio; Amada, Hideyuki; Ido, Sachio; Kumasaka, Fumiaki; Awaji, Naoki; Sánchez-Santolino, Gabriel; Ishikawa, Ryo; Ikuhara, Yuichi

    2016-10-01

    The artificial photosynthesis technology known as the Honda-Fujishima effect, which produces oxygen and hydrogen or organic energy from sunlight, water, and carbon dioxide, is an effective energy and environmental technology. The key component for the higher efficiency of this reaction system is the anode electrode, generally composed of a photocatalyst formed on a glass substrate from electrically conductive fluorine-doped tin oxide (FTO). To obtain a highly efficient electrode, a dense film composed of a nanoparticulate visible light responsive photocatalyst that usually has a complicated multi-element composition needs to be deposited and adhered onto the FTO. In this study, we discovered a method for controlling the electronic structure of a film by controlling the aerosol-type nanoparticle deposition (NPD) condition and thereby forming films of materials with a band gap smaller than that of the prepared raw material powder, and we succeeded in extracting a higher current from the anode electrode. As a result, we confirmed that a current approximately 100 times larger than those produced by conventional processes could be obtained using the same material. This effect can be expected not only from the materials discussed (GaN-ZnO) in this paper but also from any photocatalyst, particularly materials of solid solution compositions.

  8. Influence of Zn substitution for Mg on microwave dielectric properties of spinel-structured (Mg1-xZnx)Ga2O4 solid solutions

    Science.gov (United States)

    Kan, Akinori; Takahashi, Susumu; Moriyama, Tohru; Ogawa, Hirotaka

    2014-09-01

    The microwave dielectric properties and crystal structure of spinel-structured (1 - x)MgGa2O4-xZnGa2O4 ceramics were characterized in this study. From the linear variation in the lattice parameters, the formation of solid solution was obtained over the whole composition range. On the basis of the refined atomic coordinates, the variations in the volume of tetrahedron and octahedron were estimated and the expansion of the MO4 (M = Mg, Zn, and Ga) tetrahedron was recognized. The covalency of the cation-oxygen bond in the 8a site decreased with increasing composition x, suggesting the preferential Zn substitution for Mg in 8a site. The ɛr values of Zn-substituted ceramics were higher than that of MgGa2O4 ceramic. The Q · f values higher than 1.8 × 105 GHz were obtained when the ceramics were sintered at temperatures higher than 1475 °C.

  9. First principles studies on the impact of point defects on the phase stability of (AlxCr1−x2O3 solid solutions

    Directory of Open Access Journals (Sweden)

    C. M. Koller

    2016-02-01

    Full Text Available Density Functional Theory applying the generalised gradient approximation is used to study the phase stability of (AlxCr1−x2O3 solid solutions in the context of physical vapour deposition (PVD. Our results show that the energy of formation for the hexagonal α phase is lower than for the metastable cubic γ and B1-like phases–independent of the Al content x. Even though this suggests higher stability of the α phase, its synthesis by physical vapour deposition is difficult for temperatures below 800 °C. Aluminium oxide and Al-rich oxides typically exhibit a multi-phased, cubic-dominated structure. Using a model system of (Al0.69Cr0.312O3 which experimentally yields larger fractions of the desired hexagonal α phase, we show that point defects strongly influence the energetic relationships. Since defects and in particular point defects, are unavoidably present in PVD coatings, they are important factors and can strongly influence the stability regions. We explicitly show that defects with low formation energies (e.g. metal Frenkel pairs are strongly preferred in the cubic phases, hence a reasonable factor contributing to the observed thermodynamically anomalous phase composition.

  10. Room-temperature ferromagnetism of 2H-SiC-α-Al2O3 solid solution nanowires and the physical origin.

    Science.gov (United States)

    Sun, Yong; Lu, Cheng; Cui, Hao; Wang, Jing; Ma, Yanming; Wang, Chengxin

    2015-03-21

    In this work we report the first synthesis of 2H-SiC-α-Al2O3 solid solution (SS) nanowires with 2H-SiC as the host phase. The one dimensional (1D) fake binary-system exhibits interesting room-temperature ferromagnetism and spin-glass-like (SGL) behavior. This novel diluted magnetic semiconductor (DMS) was designed on the basis of SiC which is the most promising fundamental semiconductor used in next-generation electronics as the substitute for Si. A systematic investigation of the magnetic properties reveals the origin of the material's room-temperature ferromagnetism and spin-glass behavior. Spin-polarized density functional theory (DFT) calculations reveal that the net moment originates from a strong coupling between atoms around local Si vacancies produced by the SS defect reaction. Unlike random defects derived magnetic behavior, the SS resulted magnetism is significant to be utilized in functional devices since it belongs to a stable crystal structure that is possible to be prepared rationally in a controlled manner.

  11. Charged defects and ferroelectricity in (1-x)PbZrO3-x(Na1/2Bi1/2)TiO3 solid solution

    Science.gov (United States)

    Lee, Jung-Kun; Youn, Hyuk-Jun; Hong, Kug Sun; Park, Seung-Eek

    1999-01-01

    The crystal structure, dielectric/ferroelectric properties, and domain configuration of (1-x) PbZrO3-x(Na1/2Bi1/2)TiO3 solid solution with 0.14⩽x⩽0.4 were investigated using x-ray powder diffraction, D-E hysteresis, ɛr(T) measurements, and transmission electron microscopy. A sluggish transition from normal ferroelectric to relaxor state was observed as a function of composition. With an increasing amount of (Na1/2Bi1/2)TiO3, this transition was accompanied by changes in crystal structure (rhombohedral to pseudocubic), domain size and morphology (normal micron-size domain to polar nanodomain), and thermal phase transition behavior (normal ferroelectric transition to diffuse transition behavior with polarization relaxation). For intermediate compositions (i.e., x=0.25) between normal ferroelectric (x=0.16) and relaxor (x=0.4), a spontaneous relaxor-to-normal ferroelectric transition occurred at 80 °C in the ɛr(T) curve. It is suggested that this transition originates from the introduction of charged defects such as NaPb' and BiPb•, resulting in the disturbance of long-range interactions among polar ordered BO6-octahedra and short-range structural order of charged defects (i.e., NaPb'-BiPb•).

  12. Research Update: Prediction of high figure of merit plateau in SnS and solid solution of (Pb,SnS

    Directory of Open Access Journals (Sweden)

    Shiqiang Hao

    2016-10-01

    Full Text Available Direct conversion between thermal and electrical energy can be achieved by thermoelectric materials, which provide a viable route for power generation and solid state refrigeration. Here, we use a combination of energetic, electronic, and vibrational first-principles based results to predict the figure of merit performance in hole doped single crystals of SnS and (Pb,SnS. We find high ZT values for both materials, specifically for (Pb,SnS along the b-axis. Both SnS and (Pb,SnS have excellent power factors when doped, due to a combination of increased electrical conductivity (due to doping and a significantly enhanced Seebeck coefficient obtained by a doping-induced multiband effect. Anharmonic phonon calculations combined with a Debye-Calloway model show that the lattice thermal conductivity of both compounds is low, due to intrinsic anharmonicity, and is lowered further by the random, solid solution nature of the cation sublattice of (Pb,SnS. (Pb,SnS exhibits a high ZT plateau ranging from 1.3 at 300 K to 1.9 at 800 K. The overall ZT of the hole doped (Pb,SnS crystals is predicted to outperform most of the current state-of-the-art thermoelectric sulfide materials.

  13. Minor-alloyed Cu-Ni-Si alloys with high hardness and electric conductivity designed by a cluster formula approach

    Directory of Open Access Journals (Sweden)

    Dongmei Li

    2017-08-01

    Full Text Available Cu-Ni-Si alloys are widely used due to their good electrical conductivities in combination with high strength and hardness. In the present work, minor-alloying with M = (Cr, Fe, Mo, Zr was conducted for the objective of further improving their hardness while maintaining their conductivity level. A cluster-plus-glue-atom model was introduced to design the compositions of M-alloyed Cu-Ni-Si alloys, in which an ideal composition formula [(Ni,Si,M-Cu12]Cu3 (molar proportion was proposed. To guarantee the complete precipitation of solute elements in fine δ-Ni2Si precipitates, the atomic ratio of (Ni,M/Si was set as 2/1. Thus the designed alloy series of Cu93.75(Ni/Zr3.75Si2.08(Cr/Fe/Mo0.42 (at% were arc-melted into ingots under argon atmosphere, and solid-solutioned at 950 °C for 1 h plus water quenching and then aged at 450 °C for different hours. The experimental results showed that these designed alloys exhibit high hardness (HV > 1.7 GPa and good electrical conductivities (≥ 35% IACS. Specifically, the quinary Cu93.75Ni3.54Si2.08(Cr/Fe0.42Zr0.21 alloys (Cu-3.32Ni-0.93Si-0.37(Cr/Fe−0.30Zr wt% possess both a high hardness with HV = 2.5–2.7 GPa, comparable to the high-strength KLFA85 alloy (Cu-3.2Ni-0.7Si-1.1Zn wt%, HV = 2.548 GPa, and a good electrical conductivity (35–36% IACS.

  14. Powder Metallurgy Processing of a WxTaTiVCr High-Entropy Alloy and Its Derivative Alloys for Fusion Material Applications.

    Science.gov (United States)

    Waseem, Owais Ahmed; Ryu, Ho Jin

    2017-05-16

    The WxTaTiVCr high-entropy alloy with 32at.% of tungsten (W) and its derivative alloys with 42 to 90at.% of W with in-situ TiC were prepared via the mixing of elemental W, Ta, Ti, V and Cr powders followed by spark plasma sintering for the development of reduced-activation alloys for fusion plasma-facing materials. Characterization of the sintered samples revealed a BCC lattice and a multi-phase structure. The selected-area diffraction patterns confirmed the formation of TiC in the high-entropy alloy and its derivative alloys. It revealed the development of C15 (cubic) Laves phases as well in alloys with 71 to 90at.% W. A mechanical examination of the samples revealed a more than twofold improvement in the hardness and strength due to solid-solution strengthening and dispersion strengthening. This study explored the potential of powder metallurgy processing for the fabrication of a high-entropy alloy and other derived compositions with enhanced hardness and strength.

  15. Unraveling the Effects of Process Control Agents on Mechanical Alloying of Nanostructured Cu-Fe Alloy

    Directory of Open Access Journals (Sweden)

    Mina Rabiee

    2016-06-01

    Full Text Available Nanostructured Cu-20Fe alloy was synthesized by mechanical alloying process and the effects of process control agents (PCA on the phase formation, crystallite refinement and morphology of powder particles were studied. The dissolution of Fe into Cu matrix and the morphology of powder particles were analyzed by X-ray diffraction (XRD technique and scanning electron microscopy (SEM, respectively. The mean crystallite size was approximated by the method developed by Williamson and Hall. It was found that in the absence of PCA (Toluene in the present work, the iron peaks vanish after 5 h of mechanical alloying process and the mean crystallite size of the matrix decreases to 35 nm and large agglomerated particles are formed during milling. In this regard, it was found that the addition of PCA decreases the rate of crystallite refinement and formation of solid solution but does not affect the final mean crystallite size. It was also found that the addition of PCA during milling decreases the powder particle size considerably and by preventing agglomeration can lead to a finer powder particle size compared with the initial unmilled powders. It was also revealed that the effect of PCA on particle size is much greater than the effect of milling time.

  16. STRUCTURE, PHASE COMPOSITION AND PROPERTIES OF GAS-THERMAL COVERINGS OF MECHANICALLY ALLOYED THERMOREACTING COMPOSITE POWDERS OF NICKEL-ALUMINIUM SYSTEM

    Directory of Open Access Journals (Sweden)

    F. G. Lovshenko

    2015-01-01

    Full Text Available The presented results show that coverings from mechanically alloyed thermoreacting powders of system «nickel–aluminum» are nonequilibrium multiphase systems which basis represents solid solution of aluminum in nickel. It has the microcrystalline type of structure which is characterized by an advanced surface of borders of the grains and subgrains stabilized by nanodimensional inclusions of oxides and alyuminid. These coverings surpass by 1,2–1,6 times analogs in durability, hardness and wear resistance.

  17. Electrical Resistance Alloys and Low-Expansion Alloys

    DEFF Research Database (Denmark)

    Kjer, Torben

    1996-01-01

    The article gives an overview of electrical resistance alloys and alloys with low thermal expansion. The electrical resistance alloys comprise resistance alloys, heating alloys and thermostat alloys. The low expansion alloys comprise alloys with very low expansion coefficients, alloys with very low...

  18. Structural Analysis and Magnetic Properties of FeCo Alloys Obtained by Mechanical Alloying

    Directory of Open Access Journals (Sweden)

    F. Sánchez-De Jesús

    2016-01-01

    Full Text Available A systematic study on the structural and magnetic properties of Fe100-xCox alloys (10alloying is presented. Elemental powders of Fe and Co mixed in an adequate weight ratio were milled at room temperature in a shaker mixer mill using vials and balls of hardened steel as milling media with a ball : powder weight ratio of 12 : 1. The mixtures were milled for 3 h. The results show that, after milling, for almost all the composition (up to x=60, solid solutions based on bcc structures were obtained. For Co-rich alloys (x≥70, different phases were found, revealing the formation of a metastable intermetallic phase (FeCo, wairauite together with fcc-Co and hcp-Co phases. The specific saturation magnetization increases by increasing Co content, reaching a maximum value of 225 emu/g for hcp-Fe70Co30, and then it shows a diminution up to 154 emu/g for bcc-Fe30Co70. All studied alloys (Fe100-xCox present low coercivity, in the range from 0 to 65 Oe, which is lower than reported. The coercivity increases with the increment in Co, reaching a maximum of 64.1 Oe for Fe40Co60. After that, the coercivity falls up to 24.5 Oe for Co-rich alloys, which make them a very low coercive material.

  19. The Role of Compositional Tuning of the Distributed Exchange on Magnetocaloric Properties of High-Entropy Alloys

    Science.gov (United States)

    Perrin, Alice; Sorescu, Monica; Burton, Mari-Therese; Laughlin, David E.; McHenry, Michael

    2017-11-01

    This paper explores the FeCoNiCuMn high-entropy alloy system, where small departures from equiatomic composition have yielded technologically interesting 300-K Curie temperatures (Tc), making them promising for magnetocaloric applications. We also demonstrate that the small deviations from equiatomic compositions do not affect the structural stability of our single-phase fcc-based solid solutions. Room-temperature Mössbauer spectroscopy measurements provide evidence for the distributed exchange interactions (J_{ex}) occurring between the magnetic elements, which contribute to a broadened magnetocaloric effect observed for these alloys. The average hyperfine field observed in the Mössbauer spectra decreases as the Tc of the alloys decrease, confirming direct current magnetic measurements. Multiple peaks in the hyperfine field distribution are interpreted considering pairwise ferromagnetic or antiferromagnetic J_{ex} between all elements except the Cu diluent as contributing to overall magnetic exchange in the alloy.

  20. Novel Method for Making Biomedical Segregation-Free Ti-30Ta Alloy Spherical Powder for Additive Manufacturing

    Science.gov (United States)

    Xia, Yang; Fang, Zhigang Zak; Sun, Pei; Zhang, Ying; Zhu, Jun

    2018-01-01

    Ti-Ta alloys offer a good combination of high strength and low modulus among Ti-based alloys, and are ideal for biomedical applications. However, making Ti-Ta alloys has always been challenging because they tend to suffer from compositional segregation during melting due to the large difference between the melting points of Ti and Ta. This article describes a novel process for making spherical Ti-30Ta alloy powder through a unique powder metallurgy technique, namely the granulation-sintering-deoxygenation process. The results indicate that the compositional segregation problem can be overcome using this process technology. Combined with use of a deoxygenation process, the critical interstitial element, oxygen, can be controlled to < 400 ppm for powder with particle size < 75 µm. The destabilization effect of Ta on Ti-O solid solutions, and the resulting improved deoxygenation process for Ti-Ta, are discussed, as well as the phase composition and microstructure of the powders.

  1. The structure and physical properties of the ternary CuZnPt{sub 6} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ziya, A.B. [Department of Physics, Bahauddin Zakariya University, Multan-60800 (Pakistan); Institute of Materials Science, University of Tsukuba, Tsukuba 305-8573 (Japan)], E-mail: amer_ziya@yahoo.com; Takahashi, M.; Ohshima, K. [Institute of Materials Science, University of Tsukuba, Tsukuba 305-8573 (Japan)

    2008-07-01

    The ternary addition of Zn to the binary Cu-Pt system was found to result in a complete miscibility at a stoichiometric composition of CuZnPt{sub 6}. The equilibrium ground state structure is face-centered cubic (fcc) (A{sub 1}-type). The results are associated with the alloying behavior in the ternary CuMPt{sub 6} (M=3d metals) system reported previously. They verify the fact that the Pt-based primary solid solution found in binary MPt{sub 3} alloys extends its region in the phase diagram to the composition of Cu:M:Pt=1:1:6. The Debye temperature ({theta}{sub D}) obtained is smaller than that of pure Pt, whereas no significant effect is observed on the linear thermal expansion and magnetic property of the alloy.

  2. Computational studies of physical properties of Nb-Si based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang, Lizhi [Middle Tennessee State Univ., Murfreesboro, TN (United States)

    2015-04-16

    The overall goal is to provide physical properties data supplementing experiments for thermodynamic modeling and other simulations such as phase filed simulation for microstructure and continuum simulations for mechanical properties. These predictive computational modeling and simulations may yield insights that can be used to guide materials design, processing, and manufacture. Ultimately, they may lead to usable Nb-Si based alloy which could play an important role in current plight towards greener energy. The main objectives of the proposed projects are: (1) developing a first principles method based supercell approach for calculating thermodynamic and mechanic properties of ordered crystals and disordered lattices including solid solution; (2) application of the supercell approach to Nb-Si base alloy to compute physical properties data that can be used for thermodynamic modeling and other simulations to guide the optimal design of Nb-Si based alloy.

  3. The Influence of Small Quantities of Oxygen in the Structure, Microstructure, Hardness, Elasticity Modulus and Cytocompatibility of Ti-Zr Alloys for Dental Applications

    Science.gov (United States)

    Vicente, Fábio B.; Correa, Diego R. N.; Donato, Tatiani A. G.; Arana-Chavez, Victor E.; Buzalaf, Marília A. R.; Grandini, Carlos R.

    2014-01-01

    The mechanical properties of Ti alloys are changed significantly with the addition of interstitial elements, such as oxygen. Because oxygen is a strong stabilizer of the α phase and has an effect on hardening in a solid solution, it has aroused great interest in the biomedical area. In this paper, Ti-Zr alloys were subjected to a doping process with small amounts of oxygen. The influence of interstitial oxygen in the structure, microstructure and some selected mechanical properties of interest for use as biomaterial and biocompatibility of the alloys were analyzed. The results showed that in the range of 0.02 wt% to 0.04 wt%, oxygen has no influence on the structure, microstructure or biocompatibility of the studied alloys, but causes hardening of the alloys, increasing the values of the microhardness and causing variation in the elasticity modulus values. PMID:28788473

  4. Oxygen isotope analysis of carbonates in the calcite-dolomite-magnesite solid-solution by high-temperature pyrolysis: initial results.

    Science.gov (United States)

    Crowley, Stephen F; Spero, Howard J; Winter, David A; Sloane, Hilary J; Croudace, Ian W

    2008-06-01

    Accurate and efficient measurement of the oxygen isotope composition of carbonates (delta(C) (18)O) based on the mass spectrometric analysis of CO(2) produced by reacting carbonate samples with H(3)PO(4) is compromised by: (1) uncertainties associated with fractionation factors (alpha(CO)(2)C) used to correct measured oxygen isotope values of CO(2)(delta(CO(2)(18)O) to delta(C) (18)O; and (2) the slow reaction rates of many carbonates of geological and environmental interest with H(3)PO(4). In contrast, determination of delta(C) (18)O from analysis of CO produced by high-temperature (>1400 degrees C) pyrolytic reduction, using an elemental analyser coupled to continuous-flow isotope-ratio mass spectrometry (TC/EA CF-IRMS), offers a potentially efficient alternative that measures the isotopic composition of total carbonate oxygen and should, therefore, theoretically be free of fractionation effects. The utility of the TC/EA CF-IRMS technique was tested by analysis of carbonates in the calcite-dolomite-magnesite solid-solution and comparing the results with delta(C) (18)O measured by conventional thermal decomposition/fluorination (TDF) on the same materials. Initial results show that CO yields are dependent on both the chemical composition of the carbonate and the specific pyrolysis conditions. Low gas yields (+0.2 per thousand) deviations in delta(C(TC/EA) (18)O compared with delta(C(TDF) (18)O. At a pyrolysis temperature of 1420 degrees C the difference between delta(C) (18)O measured by TC/EA CF-IRMS and TDF (Delta(C(TC/EA,TDF) (18)O) was found to be negatively correlated with gas yield (r = -0.785) and this suggests that delta(C) (18)O values (with an estimated combined standard uncertainty of +/-0.38 per thousand) could be derived by applying a yield-dependent correction. Increasing the pyrolysis temperature to 1500 degrees C also resulted in a statistically significant correlation with gas yield (r = -0.601), indicating that delta(C) (18)O values (with an

  5. A neutron diffraction study of crystal and low-temperature magnetic structures within the (Na,Li)FeGe2O6 pyroxene-type solid solution series

    Science.gov (United States)

    Redhammer, Günther J.; Senyshyn, Anatoliy; Lebernegg, Stefan; Tippelt, Gerold; Dachs, Edgar; Roth, Georg

    2017-10-01

    Solid solution compounds along the Li1- x Na x FeGe2O6 clinopyroxene series have been prepared by solid state ceramic sintering and investigated by bulk magnetic and calorimetric methods; the Na-rich samples with x(Na) > 0.7 were also investigated by low-temperature neutron diffraction experiments in a temperature range of 4-20 K. For samples with x(Na) > 0.76 the crystal structure adopts the C2/ c symmetry at all measuring temperatures, while the samples display P21/ c symmetry for smaller Na contents. Magnetic ordering is observed for all samples below 20 K with a slight decrease of T N with increasing Na content. The magnetic spin structures change distinctly as a function of chemical composition: up to x(Na) = 0.72 the magnetic structure can be described by a commensurate arrangement of magnetic spins with propagation vector k = (½, 0 0), an antiferromagnetic (AFM) coupling within the Fe3+O6 octahedra zig-zag chains and an alternating AFM and ferromagnetic (FM) interaction between the chains, depending on the nature of the tetrahedral GeO4 chains. The magnetic structure can be described in magnetic space group P a21/ c. Close to the structural phase transition for sample with x(Na) = 0.75, magnetic ordering is observed below 15 K; however, it becomes incommensurately modulated with k = (0.344, 0, 0.063). At 4 K, the magnetic spin structure best can be described by a cycloidal arrangement within the M1 chains, the spins are within the a- c plane. Around 12 K the cycloidal structure transforms to a spin density wave (SDW) structure. For the C2/ c structures, a coexistence of a simple collinear and an incommensurately modulated structure is observed down to lowest temperatures. For 0.78 ≤ x(Na) ≤ 0.82, a collinear magnetic structure with k = (0 1 0), space group P C21/ c and an AFM spin structure within the M1 chains and an FM one between the spins is dominating, while the incommensurately modulated structure becomes dominating the collinear one in the

  6. Magnetic, dielectric and microwave properties of the BaFe12-xGaxO19 (x ≤ 1.2) solid solutions at room temperature

    Science.gov (United States)

    Trukhanov, S. V.; Trukhanov, A. V.; Kostishyn, V. G.; Panina, L. V.; Trukhanov, An. V.; Turchenko, V. A.; Tishkevich, D. I.; Trukhanova, E. L.; Oleynik, V. V.; Yakovenko, O. S.; Matzui, L. Yu.; Vinnik, D. A.

    2017-11-01

    The BaFe12-xGaxO19 (x = 0.1-1.2) solid solutions of the barium hexagonal ferrite of M-type were synthesized and attested by the powder X-ray diffraction method at 300 K. The unit cell parameters were refined. With increase of substitution level the parameters of unit cell monotonically decrease. These samples were investigated by the vibration magnetometry method. With increase of substitution level the magnetic parameters monotonically decrease. The concentration dependence of the TC Curie temperature as well as the MS spontaneous specific magnetization and the HC coercive force at 300 K is constructed. The microwave properties of the considered samples in the external magnetic bias field were also investigated at 300 K. It is shown that with increase of Ga3+ concentration from x = 0.1 to x = 0.6 the frequency value of the natural ferromagnetic resonance decreases in the beginning, and at further increase in concentration up to x = 1.2 it increases again. With increase in Ga3+ concentration the line width of the natural ferromagnetic resonance increases that indicates the increase of frequency range where there is an intensive absorption of electromagnetic radiation. At the same time the peak amplitude of the resonant curve changes slightly. The frequency shift of the natural ferromagnetic resonance in the external magnetic bias field takes place more intensively for the samples with small Ga3+ concentration. It is shown the prospects of use of the Ga-substituted barium hexagonal ferrite as the material effectively absorbing the high-frequency electromagnetic radiation.

  7. Dissolution of britholites and monazite / brabantite solid solutions doped with actinides; Etude de la dissolution de britholites et de solutions solides monazite / brabantite dopees avec des actinides

    Energy Technology Data Exchange (ETDEWEB)

    Du Fou De Kerdaniel, E

    2007-12-15

    In the field of the radwaste storage in underground repository, several matrices were considered as promising ceramics for the specific immobilization of actinides. Two of them, britholites and monazite/ brabantite solid solution, have been considered during this work. In order to examine the dissolution mechanisms occurring at the solid liquid interface, several leaching experiments have been conducted on (Ln{sup III}PO{sub 4} ), brabantite (Ca{sup II}An{sup IV}(PO{sub 4}){sub 2}: An = Th, U) and britholites (Ca{sub 9}Nd{sub 0.5}An{sub 0.5}{sup IV} (PO{sub 4}){sub 4.5}(SiO{sub 4}){sub 1.5}F{sub 2}: An = Th, U). Some steady experiments, performed in under saturation conditions for various pH and temperature conditions allowed to evaluate the long term behaviour of such matrices through their chemical durability. On the contrary, the thermodynamic equilibria were examined through the leaching experiments performed near the saturation conditions. By the way, various secondary phases, precipitated onto the surface of altered samples have been identified and characterized. Among them, the (Nd, Ca, Th) - rhabdophane, novelly prepared in over- saturation experiments for a thorium weight loading lower than 11 % appeared to be metastable. Indeed, it turns into TPHPH (Th{sub 2}(PO{sub 4}){sub 2}HPO{sub 4}.H{sub 2}O) and Nd - rhabdophane (NdPO{sub 4}.1/2H{sub 2}O) when increasing leaching time. (author)

  8. Synthesis, structure and magnetic ordering of the mullite-type Bi2Fe(4-x)CrxO9 solid solutions with a frustrated pentagonal Cairo lattice.

    Science.gov (United States)

    Rozova, M G; Grigoriev, V V; Bobrikov, I A; Filimonov, D S; Zakharov, K V; Volkova, O S; Vasiliev, A N; Antipov, E V; Tsirlin, A A; Abakumov, A M

    2016-01-21

    Highly homogeneous mullite-type solid solutions Bi2Fe(4-x)CrxO9 (x = 0.5, 1, 1.2) were synthesized using a soft chemistry technique followed by a solid-state reaction in Ar. The crystal structure of Bi2Fe3CrO9 was investigated using X-ray and neutron powder diffraction, transmission electron microscopy and (57)Fe Mössbauer spectroscopy (S.G. Pbam, a = 7.95579(9) Å, b = 8.39145(9) Å, c = 5.98242(7) Å, RF(X-ray) = 0.022, RF(neutron) = 0.057). The ab planes in the structure are tessellated with distorted pentagonal loops built up by three tetrahedrally coordinated Fe sites and two octahedrally coordinated Fe/Cr sites, linked together in the ab plane by corner-sharing forming a pentagonal Cairo lattice. Magnetic susceptibility measurements and powder neutron diffraction show that the compounds order antiferromagnetically (AFM) with the Néel temperatures decreasing upon increasing the Cr content from TN ∼ 250 K for x = 0 to TN ∼ 155 K for x = 1.2. The magnetic structure of Bi2Fe3CrO9 at T = 30 K is characterized by a propagation vector k = (1/2,1/2,1/2). The tetrahedrally coordinated Fe cations form singlet pairs within dimers of corner-sharing tetrahedra, but spins on the neighboring dimers are nearly orthogonal. The octahedrally coordinated (Fe,Cr) cations form antiferromagnetic up-up-down-down chains along c, while the spin arrangement in the ab plane is nearly orthogonal between nearest neighbors and collinear between second neighbors. The resulting magnetic structure is remarkably different from the one in pure Bi2Fe4O9 and features several types of spin correlations even on crystallographically equivalent exchange that may be caused by the simultaneous presence of Fe and Cr on the octahedral site.

  9. Quenching effects on piezoelectric properties and depolarization temperatures of (Bi0.5Na0.5)TiO3-based solid solution systems

    Science.gov (United States)

    Miura, Tatsuki; Nagata, Hajime; Takenaka, Tadashi

    2017-10-01

    Lead-free ferroelectric and piezoelectric ceramics, (Bi0.5Na0.5(1- x )Li0.5 x )TiO3 and (1 - y)(Bi0.5Na0.48Li0.02)TiO3-yBaTiO3 (abbreviated as BNLT100x and BNLBT4-100y, respectively), were fabricated by a quenching procedure after sintering, and then their electrical properties were investigated with the aim of increasing their depolarization temperature T d. From the measurements by a resonance-antiresonance method, the electromechanical coupling factors k 33 of BNLT100x and BNLBT4-100y were exactly the same after the quenching treatment as compared with the nonquenched one. The T d of all BNLT100x quenched from 1100 °C reached around 240 °C, and they are almost 60 °C higher for x = 0, 0.02, 0.04, and almost 80 °C higher for x = 0.08 than those of nonquenched ceramics. We also found, from the measurement on BNLBT4-100y quenched from 1100 °C, that the T d values were enhanced to higher temperature by the quenching treatment, even in the case of rhombohedral side (100y 6), and MPB composition (100y = 6). Moreover, we confirmed that the rhombohedrality 90-α and the tetragonality c/a values were enhanced by the quenching treatment. This result revealed that, even in the tetragonal symmetry, the lattice distortion (tetragonality) could also be stabilized by the quenching treatment in BNT-based solid solution ceramics.

  10. Orthodontic silver brazing alloys.

    Science.gov (United States)

    Brockhurst, P J; Pham, H L

    1989-10-01

    Orthodontic silver brazing alloys suffer from the presence of cadmium, excessive flow temperatures, and crevice corrosion on stainless steel. Seven alloys were examined. Two alloys contained cadmium. The lowest flow temperature observed was 629 degrees C for a cadmium alloy and 651 degrees C for two cadmium free alloys. Three alloys had corrosion resistance superior to the other solders. Addition of low melting temperature elements gallium and indium reduced flow temperature in some cases but produced brittleness in the brazing alloy.

  11. High-entropy alloys: Interrelations between electron concentration, phase composition, lattice parameter, and properties

    Science.gov (United States)

    Gorban', V. F.; Krapivka, N. A.; Firstov, S. A.

    2017-10-01

    An analysis of more than 200 high-entropy alloys (HEA) allowed us to find interrelations between the electron concentration, phase composition, lattice parameter, and properties of solid solutions with bcc and fcc crystal lattices. Main conditions for the appearance of high-entropy chemical compounds, such as Laves, σ, and μ phases were determined. The necessary condition for the formation of 100% high-entropy σ phase is the formation of σ phase in two-component alloys for different combinations of elements, which are components of the HEA, and the electron concentration should be 6.7-7.3 electrons per atom. To form a 100% high-entropy Laves phase, the following conditions should be fulfilled: the total negative enthalpy of mixing of alloy is about -7 kJ/mol and less; the difference between the atom sizes in a pair is more than 12%; the enthalpy of the mixing of two present elements is less than -30 kJ/mol; and the average electron concentration is 6-7 electrons per atom. It was shown that the ratios of lattice parameters of solid-solution HEA, which were experimentally determined, to the lattice parameter of the most refractory metal in the HEA determine the value of the modulus of elasticity.

  12. Effects of Sm addition on electromagnetic interference shielding property of Mg-Zn-Zr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chubin [Chongqing University, College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloy, Chongqing (China); Gannan Normal University, Jiangxi Provincial Engineering Research Center for Magnesium Alloy, Ganzhou (China); Pan, Fusheng; Chen, Xianhua [Chongqing University, College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloy, Chongqing (China); Luo, Ning [Gannan Normal University, Jiangxi Provincial Engineering Research Center for Magnesium Alloy, Ganzhou (China)

    2017-06-15

    The electromagnetic interference (EMI) shielding of Sm-containing magnesium alloys in the 30-1500 MHz testing frequency range was investigated by coaxial cable method. The results demonstrated that Mg-3Zn alloys displayed the best electromagnetic shielding property. When 0.5 wt% of Zr was added for crystal grain refinement, the shielding effectiveness (SE) was apparently reduced. The addition of the rare earth element Sm in ZK magnesium alloys can improve the electromagnetic interference shielding of magnesium alloys. The main reason for the differences in electromagnetic interference shielding of magnesium alloys was the change in conductivity. The addition of Zr in Mg-Zn alloys can refine the grains and consequently improve the grain boundary area significantly. Therefore, the number of irregularly arranged atoms at the grain boundaries increased, decreasing the conductivity of magnesium alloys and leading to a decrease in the electromagnetic interference shielding. Following the Sm addition, the Mg-Zn-Sm phase was precipitated at the grain boundaries and in cores. The precipitation of Sm-containing rare earth phases could consume the solid-soluted Zn atoms within the Mg, resulting in an increase in electrical conductivity and electromagnetic interference shielding improvement. (orig.)

  13. Characteristic of intermetallic phases in cast dental CoCrMo alloy

    Directory of Open Access Journals (Sweden)

    M. Podrez-Radziszewska

    2010-07-01

    Full Text Available Apart from chromium and molybdenum, casting alloys of cobalt usually contain also up to 0.35 % of carbon. With significant content ofcarbon, presence of carbide-forming alloying elements results in creating carbide phases. These alloys are characterised by dendriticstructure of solid solution of chromium and molybdenum in cobalt with interdendritically precipitated carbides. Because of high chromiumcontent, dominating are M23C6-type carbides, but chromium-rich carbides can be also of M7C3 and M3C2-types. The other elements inthe alloy result in creating M6C and MC-type carbides. In the case of low carbon content, creating carbides and forming intermetallicphases based on the alloying elements and cobalt become limited.The presented research was aimed at characterising structure of the cobalt-based dental alloy containing trace quantity of carbon.Characterised were intermetallic phases hardening the alloy. Microscopic examinations using light microscopy, SEM and TEM werecarried out. Chemical microanalysis of the precipitates using X-ray analyser EDS was performed, as well as phase analysis using selectedarea electron diffraction.

  14. Microstructure and properties of the eutectic 12Si-Al alloy subjected to barothermal treatment

    Science.gov (United States)

    Dedyaeva, E. V.; Nikiforov, P. N.; Padalko, A. G.; Talanova, G. V.; Shvorneva, L. I.

    2016-09-01

    A binary 12Si-Al alloy is subjected to barothermal treatment (hot isostatic pressing) at a temperature of 560°C and a pressure of 100 MPa for 3 h. This treatment is shown to result in a high degree of homogenization in the chemically and structurally heterogeneous initial alloy. As follows from the morphology of silicon microparticles, barothermal treatment of the 12Si-Al alloy leads to thermodynamically promoted silicon dissolution in the aluminum matrix up to 10 at % with the formation of a metastable supersaturated solid solution, which decomposes upon cooling. The process of removal of porosity, which results in the formation of a high-density homogeneous material, is analyzed. After a cycle of barothermal treatment, a bimodal size distribution of the silicon phase constituent forms in the 12Si-Al alloy at an average microparticle size of 2.7 μm and an average nanoparticle size of 36 nm. The linear thermal expansion coefficient of the alloy decreases after barothermal treatment, and the microhardness of the eutectic alloy is determined after this treatment. Barothermal treatment of the 12Si-Al alloy is shown to be an effective tool for the removal of microporosity, achieving a high degree of homogenization, and forming a near-optimum bimodal size distribution of the silicon structural constituent, which is comparable with or even exceeds the results of conventional heat treatment of the material at atmospheric or lower pressure.

  15. Modeling of high entropy alloys of refractory elements

    Energy Technology Data Exchange (ETDEWEB)

    Grosso, M.F. del, E-mail: delgrosso@tandar.cnea.gov.ar [Gcia. Investigacion y Aplicaciones, CNEA, Av. Gral Paz 1499, (B1650KNA), San Martin (Argentina); GCMM, UTN, FRG Pacheco, Av. H. Yrigoyen 288, Gral. Pacheco (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas, CONICET (Argentina); Bozzolo, G. [Loyola University Maryland, 4501 N. Charles St., Baltimore, MD 21210 (United States); Mosca, H.O. [Gcia. Investigacion y Aplicaciones, CNEA, Av. Gral Paz 1499, (B1650KNA), San Martin (Argentina); GCMM, UTN, FRG Pacheco, Av. H. Yrigoyen 288, Gral. Pacheco (Argentina)

    2012-08-15

    Reverting the traditional process of developing new alloys based on one or two single elements with minority additions, the study of high entropy alloys (HEA) (equimolar combinations of many elements) has become a relevant and interesting new field of research due to their tendency to form solid solutions with particular properties in the absence of intermetallic phases. Theoretical or modeling studies at the atomic level on specific HEA, describing the formation, structure, and properties of these alloys are limited due to the large number of constituents involved. In this work we focus on HEA with refractory elements showing atomistic modeling results for W-Nb-Mo-Ta and W-Nb-Mo-Ta-V HEA, for which experimental background exists. An atomistic modeling approach is applied for the determination of the role of each element and identification of the interactions and features responsible for the transition to the high entropy regime. Results for equimolar alloys of 4 and 5 refractory elements, for which experimental results exist, are shown. A straightforward algorithm is introduced to interpret the transition to the high entropy regime.

  16. Mechanical alloying of Fe-Ni based nanostructured magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Du, S.W. [School of Materials Engineering, Nanyang Technological University, B1k N4.1, Nanyang Ave., Singapore 639798 (Singapore); Ramanujan, R.V. [School of Materials Engineering, Nanyang Technological University, B1k N4.1, Nanyang Ave., Singapore 639798 (Singapore)]. E-mail: ramanujan@ntu.edu.sg

    2005-04-15

    Alloys with the composition Fe{sub 40}Ni{sub 38}B{sub 18}Mo{sub 4}, Fe{sub 49}Ni{sub 46}Mo{sub 5} and Fe{sub 42}Ni{sub 40}B{sub 18} were processed from elemental powders by mechanical alloying and the microstructure was studied by differential scanning calorimetry (DSC), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. Nanocrystalline fcc solid solution was achieved as a result of mechanical alloying in all three alloy compositions and the grain size reduced to nanoscale but lattice strain was introduced. Molybdenum was found to affect the products of mechanical alloying, specifically, the Fe{sub 3}B phase formed in the Fe{sub 42}Ni{sub 40}B{sub 18} alloy while no boride phase formed in the Fe{sub 40}Ni{sub 38}B{sub 18}Mo{sub 4} alloy. SEM studies indicated that the presence of boron was found to make the milling process easier. Elemental mapping by SEM as well as XRD results showed that molybdenum does not dissolve easily in the Fe-Ni solid solution produced by milling. The DSC results suggested that an amorphous structure together with nanocrystals was obtained in the Fe{sub 40}Ni{sub 38}B{sub 18}Mo{sub 4} and Fe{sub 42}Ni{sub 40}B{sub 18} alloys. A two-stage crystallization process was found in the Fe{sub 40}Ni{sub 38}B{sub 18}Mo{sub 4} and Fe{sub 42}Ni{sub 40}B{sub 18} alloys, the presence of boron was found to make amorphization easier. TEM investigations were consistent with these XRD and DSC results. Heat-treated samples of the Fe{sub 40}Ni{sub 38}B{sub 18}Mo{sub 4} and Fe{sub 42}Ni{sub 40}B{sub 18} alloys milled for 100 h showed that molybdenum inhibited the grain growth. The saturation magnetization of the heat-treated Fe{sub 40}Ni{sub 38}B{sub 18}Mo{sub 4} alloy milled for 100 h was stable, coercivity was reduced; on the other hand, the M {sub s} of heat-treated Fe{sub 42}Ni{sub 40}B{sub 18} alloy milled for 100 h decreased and the H {sub c} increased. This difference in magnetic

  17. Investigation on the optimized heat treatment procedure for laser fabricated IN718 alloy

    Science.gov (United States)

    Zhang, Yaocheng; Yang, Li; Chen, Tingyi; Zhang, Weihui; Huang, Xiwang; Dai, Jun

    2017-12-01

    The laser fabricated IN718 alloys were prepared by laser cladding system. The microstructure and microhardness of laser fabricated IN718 alloys were investigated after heat treatment. The microstructure and the elevated temperature mechanical properties of laser fabricated IN718 alloys were analyzed. The results showed that the microstructure of laser fabricated IN718 alloy consisted of austenitic matrix and dendritic Laves/γ eutectic. Most all Laves/γ eutectic was dissolved into austenitic matrix, and the complete recrystallization and the large grains occurred in the laser fabricated IN718 alloy after homogenization at 1080-1140 °C for 1 h, the dendritic Laves/γ eutectic was refined and the partial recrystallization occurred during the solid solution at 940-1000 °C for 1.5 h, the microhardness of the double aging (DA) alloys was about more than twice that of as-fabricated IN718 alloy. The recrystallized microstructure was obtained in the heat-treated laser fabricated IN718 alloy after 1100 °C/1 h air cooling (AC), 980 °C/1.5 h (AC), 700 °C/8 h furnace cooling (FC, 100 °C/h) to 600 °C/8 h (AC). The microhardness and the elevated temperature tensile strength were more than twice that of as-fabricated IN718 alloy due to a large concentration of γ″ phase precipitation to improve the transgranular strength and large grain to guarantee the grain boundary strength. The fracture morphologies of as-fabricated and heat-treated laser fabricated IN718 alloys were presented as the fiber dimples, the fracture mechanism of as-fabricated and heat-treated laser fabricated IN718 alloys was ductile fracture.

  18. Synthesis of V-Ti-Cr alloys by aluminothermy co-reduction of its oxides

    Directory of Open Access Journals (Sweden)

    Sanjay Kumar

    2011-12-01

    Full Text Available Synthesis of V-Ti-Cr solid solution alloy by co-reduction of V2O5, Cr2O3 and TiO2 with aluminium in an open bomb reactor was investigated. The reduction of V2O5 and Cr2O3 was highly exothermic while reduction of TiO2 was not sufficiently exothermic for self-sustaining reaction. A range of composition of V2O5, Cr2O3 and TiO2 mixture was chosen to make overall process sufficiently exothermic to sustain the reaction in a controlled manner. After the co-reduction, V-Ti-Cr-Al solid solution was obtained. As-obtained solid solution was refined by electron beam melting (EB to remove the aluminium and residual oxygen. EB melted V-Ti-Cr thus obtained contains substantially less amount of aluminium (~0.081%. Throughout the synthesis process the prepared products were analyzed using scanning electron microscope (SEM, energy dispersive X-ray fluorescence (EDAX, chemical analysis, gravimetric analysis and X-ray diffraction.

  19. Microstructure of laser-clad SiC-(Ni alloy) composite coating

    OpenAIRE

    Pei, Y.T.; Ouyang, J.H.; Lei, T.C.; Zhou, Y.

    1995-01-01

    The laser cladding technique was used to produce Ni alloy coatings with different SiC particle (SiCp) contents on steel 1045. The complete dissolution of SiCp took place during laser melting and led to a microstructural evolution of the coatings associated with the SiCp content. M7X3 or M23X6-type carboborides and Ni-base solid solution are found as the main microstructural constituents of the clad layers, and the volume fraction of the carboborides increases with increasing SiCp content. Whe...

  20. Radiation damage buildup by athermal defect reactions in nickel and concentrated nickel alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S. [School of Nuclear Science and Technology, Lanzhou University, Lanzhou, People' s Republic of China; Department of Physics and Helsinki Institute of Physics, University of Helsinki, Helsinki, Finland; Nordlund, K. [Department of Physics and Helsinki Institute of Physics, University of Helsinki, Helsinki, Finland; National Research Nuclear University MEPhI, Moscow, Russia; Djurabekova, F. [Department of Physics and Helsinki Institute of Physics, University of Helsinki, Helsinki, Finland; National Research Nuclear University MEPhI, Moscow, Russia; Granberg, F. [Department of Physics and Helsinki Institute of Physics, University of Helsinki, Helsinki, Finland; Zhang, Y. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Wang, T. S. [School of Nuclear Science and Technology, Lanzhou University, Lanzhou, People' s Republic of China

    2017-03-09

    We develop a new method using binary collision approximation simulating the Rutherford backscattering spectrometry in channeling conditions (RBS/C) from molecular dynamics atom coordinates of irradiated cells. The approach allows comparing experimental and simulated RBS/C signals as a function of depth without fitting parameters. The simulated RBS/C spectra of irradiated Ni and concentrated solid solution alloys (CSAs, NiFe and NiCoCr) show a good agreement with the experimental results. The good agreement indicates the damage evolution under damage overlap conditions in Ni and CSAs at room temperature is dominated by defect recombination and migration induced by irradiation rather than activated thermally.

  1. Understanding the Cu-Zn brass alloys using a short-range-order cluster model: significance of specific compositions of industrial alloys

    Science.gov (United States)

    Hong, H. L.; Wang, Q.; Dong, C.; Liaw, Peter K.

    2014-11-01

    Metallic alloys show complex chemistries that are not yet understood so far. It has been widely accepted that behind the composition selection lies a short-range-order mechanism for solid solutions. The present paper addresses this fundamental question by examining the face-centered-cubic Cu-Zn α-brasses. A new structural approach, the cluster-plus-glue-atom model, is introduced, which suits specifically for the description of short-range-order structures in disordered systems. Two types of formulas are pointed out, [Zn-Cu12]Zn1~6 and [Zn-Cu12](Zn,Cu)6, which explain the α-brasses listed in the American Society for Testing and Materials (ASTM) specifications. In these formulas, the bracketed parts represent the 1st-neighbor cluster, and each cluster is matched with one to six 2nd-neighbor Zn atoms or with six mixed (Zn,Cu) atoms. Such a cluster-based formulism describes the 1st- and 2nd-neighbor local atomic units where the solute and solvent interactions are ideally satisfied. The Cu-Ni industrial alloys are also explained, thus proving the universality of the cluster-formula approach in understanding the alloy selections. The revelation of the composition formulas for the Cu-(Zn,Ni) industrial alloys points to the common existence of simple composition rules behind seemingly complex chemistries of industrial alloys, thus offering a fundamental and practical method towards composition interpretations of all kinds of alloys.

  2. A novel anti-frictional multiphase layer produced by plasma nitriding of PVD titanium coated ZL205A aluminum alloy

    Science.gov (United States)

    Lu, C.; Yao, J. W.; Wang, Y. X.; Zhu, Y. D.; Guo, J. H.; Wang, Y.; Fu, H. Y.; Chen, Z. B.; Yan, M. F.

    2018-02-01

    The heat treatment (consisting of solid solution and aging), is integrated with the nitriding process of titanium coated ZL205A aluminum alloy to improve the surface and matrix mechanical properties simultaneously. Two-step duplex treatment is adopted to prepare the gradient multiphase layer on a magnesium-free ZL205A aluminum-copper based alloy. Firstly, pure titanium film is deposited on the aluminum alloy substrate using magnetron sputtering. Secondly, the Ti-coated specimen is nitrided at the solid solution temperature of the substrate alloying elements in a gas mixture of N2 and H2 and aged at 175 °C. The microstructure evolution, microhardness as well as the wear resistance of obtained multiphase layers are investigated by means of scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometer (EDS), microhardness tester and pin-on-disc tribometer. The multiphase layer, dominated by TiN0.3 or Al3Ti, is prepared with significantly increased layer depth after duplex treatment. The surface hardness of multiphase layer is remarkably improved from 23.7HV to 457HV. The core matrix hardness is also increased to 65HV after aging. The wear rate of the multiphase layer decreases about 55.22% and 49.28% in comparison with the aged and Ti coated specimens, respectively. The predominant wear mechanism for the multiphase layer is abrasive and oxidation, but severe adhesive wear for the aged and Ti coated specimens.

  3. Microstructure and Properties of W-Cu Composite/Fe-Based Powder Alloy Vacuum Brazed Joint with Different Filler Metals

    Science.gov (United States)

    Xia, C. Z.; Yang, J.; Xu, X. P.; Zou, J. S.

    2017-05-01

    W-Cu composite and Fe-based powder alloy were brazed with filler metals of Ag-Cu and Cu-Mn-Co alloys in a vacuum furnace. Both of filler metals can join W-Cu composite with Fe-based powder alloy directly in the experiment process. Microstructure, distribution of elements and fracture morphology were observed and analyzed using scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) methods, and phase composition of bonding area was analyzed by X-ray diffraction (XRD). The obtained results indicated that the smooth faying surface and dense microstructure of brazed joint were formed and the primary microstructure of brazing seam were, respectively, Ag(Cu) solid solution and Cu(Mn) solid solution, which ensured forming the stable connection of brazed joint. The bending strength of Ag-based and Cu-based brazed joint can, respectively, reach to 317 and 704 MPa, where fracture showed a typical ductile fracture characteristic. The fracture of Cu-based brazed joint located at brazing seam area, and the fracture of Ag-based brazed joint occurred in Fe-based powder alloy side.

  4. Effect of long-time, elevated-temperature exposures to vacuum and lithium on the properties of a tantalum alloy, T-111

    Science.gov (United States)

    Buzzard, R. J.; Sheffler, K. D.

    1974-01-01

    The effect of long-term, elevated-temperature vacuum and lithium exposures on the mechanical properties of T-111 (Ta-8W-2Hf) is determined. Exposure conditions were for 1000 hours at 980 or 1315 C, 5000 hours at 1315 C, and a duplex temperature exposure of 1000 hours at 980 C plus 4000 hours at 1040 C. The exposures resulted in reduced tensile and creep strengths of the T-111 in the 900 to 1100 C temperature range where a dynamic strain-age-strengthening mechanism is operative in this alloy. This strength reduction was attributed to the depletion of oxygen from solid solution in this alloy.

  5. Tuning of Photoluminescence by Cation Nanosegregation in the (CaMg) x (NaSc) 1–x Si 2 O 6 Solid Solution

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Zhiguo; Liu, Guokui; Wen, Jianguo; Mei, Zhigang; Balasubramanian, Mahalingam; Molokeev, Maxim S.; Peng, Licong; Gu, Lin; Miller, Dean J.; Liu, Quanlin; Poeppelmeier, Kenneth R.

    2016-02-03

    Controlled photoluminescence tuning is important for the optimization and modification of phosphor materials. Herein we report an isostructural solid solution of (CaMg)x(NaSc)1-xSi2O6 (0 < x < 1) in which cation nanosegregation leads to the presence of two dilute Eu2+ centers. The distinct nanodomains of isostructural (CaMg)Si2O6 and (NaSc)Si2O6 contain a proportional number of Eu2+ ions with unique, independent spectroscopic signatures. Density functional theory calculations provided a theoretical understanding of the nanosegregation and indicated that the homogeneous solid solution is energetically unstable. It is shown that nanosegregation allows predictive control of color rendering and therefore provides a new method of phosphor development.

  6. Influence of baking on the photoluminescence spectra of In{sub 1-x} Ga{sub x} As{sub y} P{sub 1-y} solid solutions grown on Inp substrates

    Energy Technology Data Exchange (ETDEWEB)

    Mishurnyi, V.A.; Gorbatchev, A.Y.; Anda, F. De; Nieto N, J. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, 78000 San Luis Potosi (Mexico)

    2004-07-01

    The influence of thermal treatments on the photoluminescence spectra of In{sub 1-x} Ga{sub x} As{sub y} P{sub 1-y} epitaxial layers of various compositions grown by LPE on In P substrates has been studied. To prevent the epitaxial layers from degradation, due to phosphor evaporation during the baking, their surface was covered by spin-on SiO{sub 2} layers. The photoluminescence spectra did not change for solid solutions whose compositions were near In P and InGaAs. For compositions in the middle of the lattice-matched region, the variations were very noticeable because the appearance of additional peaks in the luminescence spectra. This could be related to the decomposition of those solid solutions whose compositions lie inside a theoretically predicted miscibility gap. (Author)

  7. Effect of alloying elements on the corrosion behaviour of copper-nickel alloys in a marine environment

    Science.gov (United States)

    Taher, Abulmaali M. Y.

    depends on maintaining iron in a single phase in the solid solution (the maximum amount of iron can be used was 1.5 w%). Quenching improves the electrochemical behaviour of synthetic Cu-Ni-Fe alloys containing relatively high iron content. The outer layer of the passive film is porous in the absence of iron, but when iron is added, the pores disappear and cracks appear. When no sulphate is present in the solution, the passive film formed on synthetic Cu-Ni-Fe alloys consists entirely of chlorides, and Fe2O3. In the presence of sulphate FeS and NiS where detected in the corrosion film. Cu-Ni-2.0 w% Co is the most protective alloy in both the 2260 ppm sulphate artificial saline solution and N.S. sea water, and it can replace the Cu-Ni-2.0 w% Fe [quenched] alloy in marine applications. The Cu-Ni-2 w% Al alloy is recommended to be used only in clean sea water (without sulphate content). It is not recommended to use Cu-Ni-2 w% Mo, Cu-Ni-2 w% In, Cu-Ni-2 w% V, or Cu-Ni-2 w% Ti alloys in all three environments. The behaviour of Cu-Ni-2 w% Cr alloy indicates that this alloy could be used to some extent. Addition of alloying elements to the copper-nickel alloys resulted in the presence of these elements in the passive film as oxides, and sometimes chlorides.

  8. Evidence of the participation of electronic excited states in the mechanism of positronium formation in substitutional Tb1-xEux(dpm)(3) solid solutions studied by optical and positron annihilation spectroscopies

    OpenAIRE

    Fulgencio, F.; Oliveira, F.C. [UNESP; Windmoeller, D.; Brito, Hermi Felinto de; Malta, O. L.; Sa, G. F. de; Magalhaes, W.F.; Machado, J. C.

    2012-01-01

    Positronium formation in the bimary molecular solid solutions Tb1-xEux (dpm)(3) (dpm = dipivaloylmethanate) has been investigated. A strong linear correlation between the D-5(4) Tb(III) energy level excited state lifetime and the positronium formation probability has been observed. This correlation indicates that the ligand-to-metal charge transfer LMCT states act in both luminescence quenching and positronium formation inhibition, as previously proposed. A kinetic mechanism is proposed to ex...

  9. Crystal structure of (Bi0.94Sb1.06)S3 and reconsideration of cation distribution over mixed sites in the bismuthinitestibnite solid-solution series

    DEFF Research Database (Denmark)

    Poleti, Dejan; Karanović, Ljiljana; Balic Zunic, Tonci

    2012-01-01

    The intermediate member of the (Bi,Sb)(2)S-3 solid-solution series was prepared by dry synthesis at low temperature (200 degrees C) with a long annealing period in sealed silica tube. The EDS analysis yielded an empirical formula (Bi0.96Sb1.04)S-3, which is very close to the formula (Bi0.94Sb1.06...

  10. Synthesis, magnetic and dielectric characterization of nanocrystalline solid solutions of In{sub 2−x}Ni{sub x}O{sub 3} (x = 0.05, 0.10 and 0.15)

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Tokeer, E-mail: tahmad3@jmi.ac.in [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Khatoon, Sarvari [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Coolahan, Kelsey [Department of Physics and Astronomy, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028 (United States)

    2013-09-01

    Graphical abstract: Monophasic and crystalline In{sub 2−x}Ni{sub x}O{sub 3} nanoparticles of size 8–15 nm have been synthesized solvothermally and showed red shift in energy band gap which decreases on increasing Ni{sup 2+} concentration in In{sub 2}O{sub 3} host lattice. - Highlights: • Monophasic Ni-doped In{sub 2}O{sub 3} nanoparticles by solvothermal method for first time. • Plausible reaction mechanism using thermogravimetric analysis. • High surface area with small particle size obtained. • Solid solutions exhibit paramagnetism with very weak antiferromagnetic interactions. - Abstract: In{sub 2−x}Ni{sub x}O{sub 3} (x = 0.05, 0.10 and 0.15) nanoparticles were successfully synthesized by solvothermal method by the thermal decomposition of oxalate precursor at 450 °C for the first time. X-ray diffraction studies showed the formation of highly crystalline and monophasic cubic structure of In{sub 2}O{sub 3} which is attributed to the formation of solid solution. These nanoparticles show good optical transmittance in the visible region. Optical measurements showed an energy band gap which decreases with increasing Ni concentration. The grain size decreases from 15 nm to 8 nm and surface area increases from 90 to 254 m{sup 2} g{sup −1} on increasing the Ni concentration. High dielectric constant and dielectric loss has been obtained which indicates the conducting nature of these solid solutions. Magnetic measurements showed that the samples are strong paramagnetic in nature with very weak antiferromagnetic interactions. No evidence of ferromagnetism is observed for these solid solutions at room temperature.

  11. Effect of substitutions of tungsten, vanadium, molybdenum, and titanium for reduced niobium contents in Inconel Alloy 718

    Energy Technology Data Exchange (ETDEWEB)

    Ziegler, K.R.

    1985-01-01

    Inconel Alloy 718 is a nickel iron-base superalloy strengthened by the precipitation of the metastable Ni/sub 3/Nb-..gamma..'' phase. Large coherency strains between ..gamma..'' and the matrix result in a slow precipitation rate and an intermediate maximum use temperature. The combination of slow precipitation rate and the relative formability and machinability of Alloy 718 make it a popular material for the fabrication of superalloy components. The dependence on foreign sources of Nb has pointed out the desirability of reducing the Nb content of alloy 718 while maintaining the tensile and stress-rupture properties of the original alloys. The purpose of this investigation was to determine the effects of reduced Nb, and substitutions for Nb, on the properties of Alloy 718. A seris of alloys was developed having a base composition similar to Alloy 718, with reduced Nb levels of 3.00 and 1.10 wt% Nb. Substitutions of 3.0% W, 3.0W + 0.9V or Mo increased from 3.0 to 5.8% were made for the Nb in these alloys. Two additional alloys, one containing 3.49% Nb and 1.10% Ti and another containing 3.89% Nb and 1.27% Ti, were also studied. Solution and age heat treatments were optimized for each alloy to develop a proper microstructure. The reduction in Nb content required the substitution of other elements to maintain the properties of the original alloy. Additions of solid-solution elements to a reduced Nb alloy had no significant effect on the properties of the alloys under either process condition.

  12. Dimensional t-factor variation and increase of stability of the ferroelectric state in (Na0.5Bi0.5)TiO3-based solid solutions

    Science.gov (United States)

    Ishchuk, V. M.; Kuzenko, D. V.; Sobolev, V. L.

    The influence of the B-site ion substitutions in (1‑x)(Bi1/2Na1/2)TiO3-xBaTiO3 system of solid solutions on the relative stability of the antiferroelectric (AFE) and ferroelectric (FE) phases has been studied. The ions of zirconium, tin, and (In0.5Nb0.5), (Fe0.5Nb0.5), (Al0.5V0.5) ion complexes have been used as substituting elements. An increase in the concentration of the substituting ion results in a near linear variation in the size of the crystal lattice cell. Along with the cell size variation, a change in the relative stability of the AFE and FE phases takes place according to the changes of the tolerance factor of the solid solution. An increase in the tolerance factor leads to the increase in the temperature of the FE-AFE phase transition, and vice versa. Obtained results indicate the way for raising the temperature of the FE-AFE phase transition in (Bi1/2Na1/2)TiO3-based solid solutions.

  13. Magnetic and electrical properties of (FeIn{sub 2}S{sub 4}){sub 1−x}(CuIn{sub 5}S{sub 8}){sub x} solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Trukhanov, S.V., E-mail: truhanov@ifttp.bas-net.by [Scientific Practical Materials Research Centre of NASB, 220072 Minsk (Belarus); Bodnar, I.V.; Zhafar, M.A., E-mail: chemzav@bsuir.by [Belarussian State University of Informatics and Radioelectronics, 220013 Minsk (Belarus)

    2015-04-01

    In this study, single crystals of FeIn{sub 2}S{sub 4} and CuIn{sub 5}S{sub 8} compounds, and (FeIn{sub 2}S{sub 4}){sub 1−x}(CuIn{sub 5}S{sub 8}){sub x} solid solutions were grown using the Bridgman method. The magnetic and electrical properties of the samples obtained were investigated at temperatures of 5–300 K and in a magnetic field range of 0–14 T. It was established that all of the solid solutions were paramagnets down to low temperatures of ~10 K. It was shown that the ground state of the magnetic phase of the samples was a spin glass state, where the freezing temperature increased monotonically with the increase in the concentration of Fe{sup 2+} cations. All of the samples exhibited semiconductor characteristics in terms of electrical resistivity. The concentration-dependent critical magnetic temperatures, magnetic moment, and activation energy were plotted, which are probably explained by the magnetic state formation of the (FeIn{sub 2}S{sub 4}){sub 1−x}(CuIn{sub 5}S{sub 8}){sub x} solid solution single crystals based on the empirical Goodenough–Kanamori rules.

  14. X-ray excited photoluminescence near the giant resonance in solid-solution Gd(1-x)Tb(x)OCl nanocrystals and their retention upon solvothermal topotactic transformation to Gd(1-x)Tb(x)F3.

    Science.gov (United States)

    Waetzig, Gregory R; Horrocks, Gregory A; Jude, Joshua W; Zuin, Lucia; Banerjee, Sarbajit

    2016-01-14

    Design rules for X-ray phosphors are much less established as compared to their optically stimulated counterparts owing to the absence of a detailed understanding of sensitization mechanisms, activation pathways and recombination channels upon high-energy excitation. Here, we demonstrate a pronounced modulation of the X-ray excited photoluminescence of Tb(3+) centers upon excitation in proximity to the giant resonance of the host Gd(3+) ions in solid-solution Gd1-xTbxOCl nanocrystals prepared by a non-hydrolytic cross-coupling method. The strong suppression of X-ray excited optical luminescence at the giant resonance suggests a change in mechanism from multiple exciton generation to single thermal exciton formation and Auger decay processes. The solid-solution Gd1-xTbxOCl nanocrystals are further topotactically transformed with retention of a nine-coordinated cation environment to solid-solution Gd1-xTbxF3 nanocrystals upon solvothermal treatment with XeF2. The metastable hexagonal phase of GdF3 can be stabilized at room temperature through this topotactic approach and is transformed subsequently to the orthorhombic phase. The fluoride nanocrystals indicate an analogous but blue-shifted modulation of the X-ray excited optical luminescence of the Tb(3+) centers upon X-ray excitation near the giant resonance of the host Gd(3+) ions.

  15. TTP and TTT diagrams for quench sensitivity and ageing of 1424 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Davydov, V.G.; Ber, L.B.; Kaputkin, E.Y.; Komov, V.I.; Ukolova, O.G.; Lukina, E.A. [All-Union Inst. of Light Alloys, Moscow (Russian Federation)

    2000-03-15

    TTP and TTT diagrams of 1424 alloy (system Al-Li-Mg-Sc-Zr) within temperature interval for quench sensitivity 100-450 C and temperature interval for ageing 100-250 C were obtained. Solid solution decomposition kinetics were determined by electroconductivity and tensile properties measurements. Phase transformations have been investigated using by high sensitivity X-ray phase analysis, TEM, EDX and DSC. Cooling rate at quenching enough to suppress solid solution decomposition estimated by {upsilon}, UTS and YS changes criteria is equal to {proportional_to}2 C s{sup -1}. At temperature interval 200-350 C {upsilon}, UTS and YS were changed with peak near 275-300 C (temperature of the minimal stability) after the endurance 1-4 min. TTT diagram showed, that the solid solution decomposition with precipitation of S{sub 1}-phase (Al{sub 2}MgLi) in temperature range 250-300 C begins with minimal used duration (15 s), the critical rate of cooling necessary to suppress S{sub 1}12 C s{sup -1}. In temperature interval 150-175 C {upsilon}, UTS and YS have a second peak after the endurance more than 8 min. At that interval {delta}'-phase precipitates were found. For ageing temperature interval the peak strength after ageing was found at 150-175 C during 16-32 h. Time-temperature regions of GP zones, ordered solid solutions domains, S'{sub 1}(S{sub 1}) phases existence were established. (orig.)

  16. Impact of Mg2+ ion incorporation on the phase development of ZrO2-type solid solutions and their application in the catalytic oxidation of carbon monoxide

    Science.gov (United States)

    Nemec, Vinko; Kaper, Helena; Pétaud, Guillaume; Ivanda, Mile; Štefanić, Goran

    2017-07-01

    The precursors of ZrO2-MgO system covering the whole concentration range were prepared by co-precipitation of the corresponding nitrate salts. The obtained precursors were calcined in air at different temperatures up to 1000 °C and analyzed at room temperature using X-ray powder diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESM) and energy dispersive X-ray spectrometry (EDS). Maximum solubility of Mg2+ ions (∼32 mol%) was obtained in the amorphous precursor. After crystallization at 600 °C the solid solubility of Mg2+ ions decreases to ∼26 mol% of which ∼22 mol% was incorporated inside ZrO2-type lattice while the remaining part of Mg2+ ions was adsorbed on the surface of the particles. Further thermal treatment decreases solubility of Mg2+ ions to 18 mol% (800 °C) and finally to 9 mol% (1000 °C). On the other side of the concentration range, the solubility of Zr4+ ions in MgO lattice was 10 mol%) polymorphs. A precise determination of unit-cell parameters shows that the increase in the Mg2+ content causes a decrease in the parameter c of tetragonal ZrO2 lattice, which in a solid solution with a Mg2+ content ≥10 mol% becomes very close to the lattice parameter a (approaching cubic lattice). The results of FE-SEM analysis show that the addition of Mg2+ ions promotes sintering of samples. The influence of thermal treatment on the crystallization of the amorphous precursors to ZrO2-type lattice was examined by differential thermal analysis and thermogravimetric measurement. The obtained results show that the crystallization temperature increases with increasing Mg content, from 445 °C (0 mol% MgO) to 625 °C (∼50 mol% MgO). The ZrO2 doped with 3 mol% MgO was used as catalyst support for platinum nanoparticles and compared to commercially available 3% yttria-doped stabilized zirconia (3YSZ). The catalysts were used for catalytic CO oxidation and show slightly better performance of the ZrO2-MgO system, which

  17. Neutron powder diffraction investigation of magnetic structure and spin reorientation transition of HoFe{sub 1-x}Cr{sub x}O{sub 3} solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xinzhi [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China); Hao, Lijie, E-mail: haolijie@ciae.ac.cn [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China); Liu, Yuntao; Ma, Xiaobai; Meng, Siqin; Li, Yuqing; Gao, Jianbo; Guo, Hao; Han, Wenze; Sun, Kai; Wu, Meimei [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China); Chen, Xiping; Xie, Lei [Institute of Nuclear Physics and Chemistry, CAEP, Mianyang 621900 (China); Klose, Frank [Australian Nuclear Science and Technology Organization, Lucas Heights, New South Wales 2234 (Australia); Department of Physics and Materials Science, The City University of Hong Kong, Hong Kong (China); Chen, Dongfeng, E-mail: dongfeng@ciae.ac.cn [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China)

    2016-11-01

    Orthoferrite solid solution HoFe{sub 1−x}Cr{sub x}O{sub 3} (x=0, 0.2,…,1.0) was synthesized via solid state reaction methods. The crystal structure, magnetism and spin reorientation properties of this system were investigated by X-ray diffraction, neutron powder diffraction and magnetic measurements. For compositions of x≤0.6, the system exhibits similar magnetic properties to HoFeO{sub 3}. With increasing Cr-doping, the system adopts a Γ{sub 4}(G{sub x}A{sub y}F{sub z}) magnetic configuration with a decreased Neel temperature from 640 K to 360 K. A Γ{sub 42} spin reorientation of Fe(Cr){sup 3+} was also observed in this system with an increase in transition temperature from 56 K to about 200 K due to competition between the Fe(Cr)–Fe(Cr) and Ho–Fe(Cr) interactions. For the x≥0.8, the system behaves more like HoCrO{sub 3} which adopts a Γ{sub 2}(F{sub x}C{sub y}G{sub z}) configuration with no spin reorientation below the Neel temperature T{sub N}. Throughout the whole substitution range, we found that the saturated moment of Fe(Cr) was less than the ideal value for a free ion, which implies the existence of spin fluctuation in this system. A systematic magnetic structure variation with Cr-substitution is revealed by Rietveld refinement. A phase diagram combining the results of the magnetic measurements and neutron powder diffraction results was obtained. - Highlights: • With Cr-substitution in the HoFe{sub 1−x}Cr{sub x}O{sub 3} system, A Γ{sub 42} spin reorientation of Fe(Cr){sup 3+} was observed with an increase in transition temperature from 56 K to about 200 K for x=0−0.6. • The saturated moment of Fe(Cr) position was found to be systematically less than the ideal value of free ion, and thus implies the presence of spin quantum fluctuation. • A composition–temperature phase diagram throughout x=0–1 for HoFe{sub 1−x}Cr{sub x}O{sub 3} system was established.

  18. Synthesis, composition, and structure of sillenite-type solid solutions in the Bi2O3-SiO2-MnO2 system.

    Science.gov (United States)

    Mel'nikova, Tatyana I; Kuz'micheva, Galina M; Rybakov, Victor B; Bolotina, Nadezhda B; Dubovsky, Alexander B

    2011-03-07

    Individual compounds and solid solutions are obtained under hydrothermal conditions in the Bi(2)O(3)-SiO(2)-MnO(2) system in the form of faceted crystals and epitaxial films on the Bi(24)Si(2)O(40) substrate. The crystals have the shape of a cube (for the molar ratio of the starting components Na(2)SiO(3)·9H(2)O:Mn(NO(3))(2)·6H(2)O > 1), a tetrahedron (for Na(2)SiO(3)·9H(2)O:Mn(NO(3))(2)·6H(2)O < 1), or a tetrahedron-cube combination (for Na(2)SiO(3)·9H(2)O:Mn(NO(3))(2)·6H(2)O = 1). Crystal-chemical analysis based on the data of single-crystal and powder X-ray diffraction, IR spectra, and the results of calculation of the local balance by the bond-valence method reveals formation of the Bi(24)(Si(4+),Mn(4+))(2)O(40) phases, which probably include Mn(5+) ions (epitaxial films), as well as the Bi(24)(Si(4+),Bi(3+),Mn(4+))(2)O(40) and Bi(24)(Si(4+),Mn(4+))(2)O(40) phases in the (1 - x)Bi(3+)(24)Si(4+)(2)O(40) - x(Bi(3+)(24)Mn(4+)(2)O(40)) system and the Bi(24)(Bi(3+),Mn(4+))(2)O(40) phase in the (1 - x)Bi(3+)(24)Bi(3+)(2)(O(39)ⁱ(1)) - x(Bi(3+)(24)Mn(4+)(2)O(40)) system. Precision X-ray diffraction studies of single crystals of the Bi(24)(Bi,Si,Mn)(2)O(40) general composition show that these sillenites crystallize in space group P23 and not I23 as the Bi(24)Si(2)O(40) phase. The dissymmetrization of sillenite phases is observed for the first time. It is explained by a kinetic (growth) phase transition of the order-disorder type due to population of a crystallographic site by atoms with different crystal-chemical properties and quasi-equilibrium conditions of crystal growth in the course of a hydrothermal synthesis below 400 °C at unequal molar amounts of the starting components in the batch. © 2011 American Chemical Society

  19. Comparison of SA508 Gr.3 and SA508 Gr.4N Low Alloy Steels for Reactor Pressure Vessel Steel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Chul; Lee, B. S

    2009-12-15

    The microstructural characteristics and mechanical properties of SA508 Gr.3 Mn-Mo-Ni low alloy steel and SA508 Gr.4N Ni-Mo-Cr low alloy steel were investigated. The differences in the stable phases between these two low alloy steels were evaluated by means of a thermodynamic calculation using ThermoCalc. They were then compared to microstructural features and correlated with mechanical properties. Mn-Mo-Ni low alloy steel shows the upper bainite structure which has the coarse cementite in the lath boundaries. However, Ni-Mo-Cr low alloy steel shows the mixture of lower bainite and tempered martensite structure that homogeneously precipitates the small carbides such as M{sub 23}C{sub 6} and M{sub 7}C{sub 3} due to an increase of hardenability and Cr addition. In the mechanical properties, Ni-Mo-Cr low alloy steel has higher strength and toughness than Mn-Mo-Ni low alloy steel. Ni and Cr additions increase the strength by solid solution hardening. Besides, microstructural changes from upper bainite to tempered martensite improve the strength of the low alloy steel by grain refining effect. And the changes in the precipitation behavior by Cr addition improve the ductile-brittle transition behavior along with a toughening effect of Ni addition.

  20. Depth-dependent Vertical-to-Horizontal (V/H) Ratios of Free-Field Ground Motion Response Spectra for Deeply Embedded Nuclear Structures

    Energy Technology Data Exchange (ETDEWEB)

    Wei, X. [Brookhaven National Lab. (BNL), Upton, NY (United States); Braverman, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Miranda, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Rosario, M. E. [Brookhaven National Lab. (BNL), Upton, NY (United States); Costantino, C. J. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-02-01

    This report documents the results of a study to determine the depth-dependent V/H ratios of ground motion response spectra in the free field. The V/H ratios reported herein were developed from a worldwide database of surface and downhole acceleration recordings obtained from 45 vertical array stations. This database was specifically compiled for this project, and includes information from a diversity of active tectonic regions (California, Alaska, Taiwan, Japan), site conditions (rock to soft soil), ground motion intensity levels (PGAs between 0.01 g and 0.50 g), magnitudes (between ML 2.78 and JMA 8.1), epicentral distances (between 3.2 km and 812 km), and source depths (between 1.2 km and 112 km), as well as sensors at surface and at a wide range of depths relevant to the project. To study the significance of the depth effect, V/H ratios from all the records were sorted into a number of depth bins relevant to the project, and statistics (average, standard deviation, coefficient of variation, 16th, 50th, and 84th percentiles) of the V/H ratios within each bin were computed. Similar analyses were repeated, controlling for different site conditions, ground motion intensity levels, array locations, and source depths, to study their relative effect on the V/H ratios. Our findings confirm the importance of the depth effect on the V/H ratios. The research findings in this report can be used to provide guidance on the significance of the depth effect, and the extent to which this effect should be considered in the seismic design of deeply embedded SMR structures and NPP structures in general.

  1. Non-monotonic compositional dependence of isothermal bulk modulus of the (Mg1–xMnxCr2O4 spinel solid solutions, and its origin and implication

    Directory of Open Access Journals (Sweden)

    Xi Liu

    2016-12-01

    Full Text Available The compressibility of the spinel solid solutions, (Mg1−xMnxCr2O4 with x = 0.00 (0, 0.20 (0, 0.44 (2, 0.61 (2, 0.77 (2 and 1.00 (0, has been investigated by using a diamond-anvil cell coupled with synchrotron X-ray radiation up to ∼10 GPa (ambient T. The second-order Birch–Murnaghan equation of state was used to fit the PV data, yielding the following values for the isothermal bulk moduli (KT, 198.2 (36, 187.8 (87, 176.1 (32, 168.7 (52, 192.9 (61 and 199.2 (61 GPa, for the spinel solid solutions with x = 0.00 (0, 0.20 (0, 0.44 (2, 0.61 (2, 0.77 (2 and 1.00 (0, respectively (KT′ fixed as 4. The KT value of the MgCr2O4 spinel is in good agreement with existing experimental determinations and theoretical calculations. The correlation between the KT and x is not monotonic, with the KT values similar at both ends of the binary MgCr2O4MnCr2O4, but decreasing towards the middle. This non-monotonic correlation can be described by two equations, KT = −49.2 (11x + 198.0 (4 (x ≤ ∼0.6 and KT = 92 (41x + 115 (30 (x ≥ ∼0.6, and can be explained by the evolution of the average bond lengths of the tetrahedra and octahedra of the spinel solid solutions. Additionally, the relationship between the thermal expansion coefficient and composition is correspondingly reinterpreted, the continuous deformation of the oxygen array is demonstrated, and the evolution of the component polyhedra is discussed for this series of spinel solid solutions. Our results suggest that the correlation between the KT and composition of a solid solution series may be complicated, and great care should be paid while estimating the KT of some intermediate compositions from the KT of the end-members.

  2. Mechanosynthesis and structural characterization of nanocrystalline Ce{sub 1–x}Y{sub x}O{sub 2–δ} (x=0.1–0.35) solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Fabián, Martin, E-mail: fabianm@saske.sk [Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Institute of Geotechnics, Slovak Academy of Sciences, Watsonova 45, 04001 Košice (Slovakia); Antić, Bratislav [“Vinča” Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Girman, Vladimír [Institute of Physics, P. J. Šafárik University, Park Angelinum 9, 04154 Košice (Slovakia); Vučinić-Vasić, Milica [Faculty of Technical Sciences, University of Novi Sad, Trg D. Obradovića 6, 21000 Novi Sad (Serbia); Kremenović, Aleksandar [Laboratory of Crystallography, Faculty of Mining and Geology, University of Belgrade, Djusina 7, 11001 Belgrade (Serbia); Suzuki, Shigeru [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, 980-8577 Sendai (Japan); Hahn, Horst [Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Šepelák, Vladimír [Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Institute of Geotechnics, Slovak Academy of Sciences, Watsonova 45, 04001 Košice (Slovakia)

    2015-10-15

    A series of nanostructured fluorite-type Ce{sub 1–x}Y{sub x}O{sub 2–δ} (0≤x≤0.35) solid solutions, prepared via high-energy milling of the CeO{sub 2}/Y{sub 2}O{sub 3} mixtures, are investigated by XRD, HR-TEM, EDS and Raman spectroscopy. For the first time, complementary information on both the long-range and short-range structural features of mechanosynthesized Ce{sub 1–x}Y{sub x}O{sub 2–δ}, obtained by Rietveld analysis of XRD data and Raman spectroscopy, is provided. The lattice parameters of the as-prepared solid solutions decrease with increasing yttrium content. Rietveld refinements of the XRD data reveal increase in microstrains in the host ceria lattice as a consequence of yttrium incorporation. Raman spectra are directly affected by the presence of oxygen vacancies; their existence is evidenced by the presence of vibration modes at ~560 and ~600 cm{sup –1}. The detailed spectroscopic investigations enable us to separate extrinsic and intrinsic origin of oxygen vacancies. It is demonstrated that mechanosynthesis can be successfully employed in the one-step preparation of nanocrystalline Ce{sub 1–x}Y{sub x}O{sub 2–δ} solid solutions. - Graphical abstract: Mechanosynthesis of nanocrystalline Ce{sub 1–x}Y{sub x}O{sub 2–δ} (x=0.1–0.35) solid solutions. - Highlights: • One-step mechanosynthesis of nanoscale Ce{sub 1–x}Y{sub x}O{sub 2–δ} (0≤x≤0.35) solid solutions. • Complementary information on the long-range and short-range structural features of mechanosynthesized Ce{sub 1–x}Y{sub x}O{sub 2–δ} is provided. • Structural variations as a response to the yttrium doping. • Separation of extrinsic and intrinsic origin of the induced oxygen vacancies.

  3. Simultaneously enhanced mechanical and damping properties of Mg-Zn-Y alloys reinforced with LPSO phase

    Science.gov (United States)

    Wang, Jingfeng; Wang, Haibo; Li, Shun; Wang, Shaohua

    2017-07-01

    The microstructure, mechanical properties and damping capacities of Mg-Zn-Y alloys were investigated and compared systematically. The results showed that strength and damping of the alloy were increasing markedly with the increase of the volume fraction of long period stacking ordered (LPSO) phase (8%, 16%, 32%, 64%, respectively) on the whole. The corporate effect of LPSO phase and solid solution atoms was beneficial to the strengths. The Mg-1.36Zn-2.28Y can be classified as high damping metals (Q-1≧0.01) at strain amplitudes surpassing 1×10-3. With increasing of the LPSO phase, the critical strain amplitudes of alloys gradually decreased so that alloys can break away from pinning points more easily, thus, achieving a more superior damping performance. In addition, the strain amplitude-independent damping and strain amplitude-dependent damping of the Mg-Zn-Y alloys both increased. The damping capacities of the alloys cannot be explained by the Granato-Lücke theory exclusively.

  4. Physical properites of O- and N-containing V-Cr-Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.H.; Kupperman, D.; Park, E.T.; Dragel, G. [Argonne National Laboratory, Chicago, IL (United States)

    1996-04-01

    Incorporation of O in the surface of V-Ti-Cr alloys has been investigated in controlled environments at 550-750{degrees}C, and test were performed to determine the physical properties of V-Cr-Ti-O solid solutions. The amount of O in the alloys has been determined by weight change measurements. Microhardness was used to determine O depth profiles of the alloys. X-ray diffraction indicated a phase transformation from body-centered cubic (bcc) to tetragonal in the lattice that was highly stressed because of O incorporation. Back-scattered-electron images and electron-energy-dispersive spectra revealed Cr depletion near alloy grain boundaries. Elastic modulus and Vickers hardness increased in O-enriched V-Cr-Ti alloys. Hardening of the alloys results from O atoms on face-centered interstitial sites in the bcc sublattice and the formation of homogeneous oxide or nitride phases via internal oxidation or nitridation. The O,N-enriched surface region exhibited the extraordinarily high Vickers hardness of {approx}18 GPa (1800 kg/mm{sup 2}), a value that is typical of oxides nitrides, or carbides, or that is obtainable by ion-beam irradiation of metals.

  5. High-temperature gas-cooled reactor helium compatibility studies: results of 10,000-hour exposure of selected alloys in simulated reactor helium

    Energy Technology Data Exchange (ETDEWEB)

    Lechtenberg, T.A.; Stevenson, R.D.; Johnson, W.R.

    1980-05-01

    Work on the HTGR Helium Compatibility Task accomplished during the period March 31, 1977 through September 30, 1979, is documented in this report. Emphasis is on the results and analyses of creep data to 10,000 h and the detailed metallurgical evaluations performed on candidate alloy specimens tested for up to 10,000 h. Long-term creep and unstressed aging data in controlled-impurity helium and in air at 800, 900, and 1000/sup 0/C are reported for alloys included in the program in FY-76, including the wrought solid-solution-strengthened alloys, Hastelloy X, Hastelloy S, RA 333, and HD 556, and the centrifugally cast austenitic alloys, HK 40, Supertherm, Manaurite 36X, Manaurite 36XS, and Manaurite 900.

  6. Iron atoms redistribution in oxide films of Zr-Fe, Zr-Fe-Cu alloys during corrosion in autoclave at 350°C

    Science.gov (United States)

    Filippov, V.; Bateev, A.

    2016-04-01

    The data on changes of iron atoms state in the oxide films of binary Zr-1.24 mas.%Fe and ternary Zr-1.39 mas.%Fe-0.60 mas.%Cu zirconium alloys are obtained. Alloys are subjected to corrosion tests under autoclave conditions at 350°C temperature in a steam-water environment under pressure p = 16.8 MPa. In initial specimens of the alloys the iron atoms are in the form of intermetallic compounds. In oxide films the decomposition of intermetallic compounds and formation of new compounds occurs with structural phase distortion. In the oxide films metallic the metallic iron particles α-Fe, iron oxide in the form of hematite α-Fe2O3, solid solutions of iron ions in ZrO2 are formed. The phase composition of the oxide films depends on the alloy composition and changes during the growth process of the oxide film.

  7. Mechanical behavior of novel W alloys produced by HIP

    Energy Technology Data Exchange (ETDEWEB)

    Pastor, J.Y.; Martin, A.; Llorca, J. [Madrid Univ. Politecnica, Dept de Ciencia de Materiales (Spain); Monge, M.A.; Pareja, R. [Madrid Univ. Carlos 3, Dept. de Fisica (Spain)

    2007-07-01

    Full text of publication follows: W appears to be one of the candidate materials being considered for making plasma-facing components (PFCs) in a future fusion power reactor because of its refractory characteristics, low tritium retention and low sputtering yielding. However, its use in PFCs requires the development of W materials that, in addition to these properties, maintains good mechanical properties at high temperatures. In W, high temperature strength and creep resistance may be effectively increased by solid-solution and dispersion strengthening. Sintering could be a suitable method to produce solid-solution and dispersion strengthening in W alloys for these applications if their recrystallization temperature is high enough and the grain growth is restrained. The aim of the present work is to investigate the mechanical properties of W materials produced by liquid phase sintering using Ti as sintering activator and nanoparticles of Y{sub 2}O{sub 3} as strengthening dispersoids. The mechanical behaviour of pure W and W alloys, having 0.5 wt % Y{sub 2}O{sub 3}, X Wt % Ti and 0.5 wt % Y{sub 2}O{sub 3} + X wt % Ti prepared by powder metallurgy have been studied (0{<=}X{<=}4). Three point bending tests have been performed on 2 x 2 x 25 mm{sup 3} specimens cut from ingots consolidated by a two-stage hot isostatic pressing process. The bending strength, fracture toughness and elastic modulus have been determined as a function of temperature. The fracture surfaces have been analyzed to find the fracture mode and investigate the temperature dependence of the mechanical properties and fracture mechanisms. The effect of the Y{sub 2}O{sub 3} dispersion and Ti content on the mechanical properties is also investigated. (authors)

  8. Auger electron spectroscopy study of oxidation of a PdCr alloy used for high-temperature sensors

    Science.gov (United States)

    Boyd, Darwin L.; Zeller, Mary V.; Vargas-Aburto, Carlos

    1993-01-01

    A Pd-13 wt. percent Cr solid solution is a promising high-temperature strain gage alloy. In bulk form it has a number of properties that are desirable in a resistance strain gage material, such as a linear electrical resistance versus temperature curve to 1000 C and stable electrical resistance in air at 1000 C. However, unprotected fine wire gages fabricated from this alloy perform well only to 600 C. At higher temperatures severe oxidation degrades their electrical performance. In this work Auger electron spectroscopy was used to study the oxidation chemistry of the alloy wires and ribbons. Results indicate that the oxidation is caused by a complex mechanism that is not yet fully understood. As expected, during oxidation, a layer of chromium oxide is formed. This layer, however, forms beneath a layer of metallic palladium. The results of this study have increased the understanding of the oxidation mechanism of Pd-13 wt. percent Cr.

  9. Effect of electronic structures on catalytic properties of CuNi alloy and Pd in MeOH-related reactions

    Science.gov (United States)

    Tsai, An-Pang; Kimura, Tomofumi; Suzuki, Yukinori; Kameoka, Satoshi; Shimoda, Masahiko; Ishii, Yasushi

    2013-04-01

    We investigated the catalytic properties of a CuNi solid solution and Pd for methanol-related reactions and associated valence electronic structures. Calculations and X-ray photoelectron spectroscopy measurements revealed that the CuNi alloy has a similar valence electronic structure to Pd and hence they exhibited similar CO selectivities in steam reforming of methanol and decomposition of methanol. Samples prepared by various processes were found to have similar CO selectivities. We conjecture that alloying of Cu and Ni dramatically alters the valence electronic structures, making it similar to that of Pd so that the alloy exhibits similar catalytic properties to Pd. First-principles slab calculations of surface electronic structures support this conjecture.

  10. Influence of SSTT, ageing regime and stretching on IGC, complex of properties and precipitation behavior of 6013 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Davydov, V.G.; Siniavski, V.S.; Ber, L.B.; Valkov, V.D.; Kalinin, V.D.; Titkova, Ye.V.; Ukolova, O.G.; Lukina, Ye.A.; Shvechkov, Ye.I.; Kaputkin, Ye.Ya. [All-Union Inst. of Light Alloys, Moscow (Russian Federation); Rendigs, K.-H.; Tempus, G.

    2000-07-01

    The influence of solid solution treatment temperature (SSTT), stretching and two- and three-stage ageing regimes on the tensile properties, IGC, K{sub c} (K{sub c{sub 0}}) and FCPR of sheets from 6013 alloy in comparison with properties of 6013T6 and 6056T78 alloys sheets has been investigated. The recommended regimes including stretching and two- and three-stage ageing allow to eliminate IGC and to increase strength properties of sheets from 6013 alloy, providing for the higher values of the strength, fracture toughness and the decrease of FCPR in comparison with 6056T78. The precipitates phase composition in body of grains and on the GB is the same - Q'({beta}')-phases. Their sizes and the width of PFZ are lower than after the standard overageing regime (T78). (orig.)

  11. Processing and characterization of Al-Al3Nb prepared by mechanical alloying and equal channel angular pressing

    Science.gov (United States)

    Chandran, P.; Zafari, A.; Lui, E. W.; Xia, K.

    2017-05-01

    Mechanically alloyed Al with immiscible elements such as Nb can lead to a uniform distribution of nanoscaled precipitates which are highly stable compared to conventional alloying and with excellent interface, resulting in significant increase in strength without problems associated with nano ceramic particles in metal matrix composites. Although immiscible, Nb can be alloyed with Al through mechanical milling, forming trialuminide (Al3Nb), either directly or upon subsequent precipitation, which possesses high strength, stiffness and stability at elevated temperatures. In the present study, Al-5 at.% Nb supersaturated solid solution was achieved after prolonged ball milling and nano Al3Nb precipitates were formed during subsequent ageing at 530°C. The Al-Al3Nb powder was consolidated by equal channel angular pressing (ECAP) at 400°C, resulting in a fully dense material with a uniform distribution of nanoscaled Al3Nb precipitates in the Al matrix.

  12. Giant magnetic coercivity in YNi{sub 4}B-type SmNi{sub 3}TB (T=Mn–Cu) solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Jinlei; Yan, Chang [Research Center for Solid State Physics and Materials, School of Mathematics and Physics, Suzhou University of Science and Technology, Suzhou 215009 (China); Yapaskurt, V.O. [Department of Petrology, Geological Faculty Moscow State University, Leninskie Gory, Moscow 119992 (Russian Federation); Morozkin, A.V., E-mail: morozkin@tech.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation)

    2016-12-01

    The effects of transition metal substitution for Ni on the magnetic properties of the YNi{sub 4}B-type SmNi{sub 4}B via SmNi{sub 3}TB (T=Mn, Fe, Co, Cu) solid solutions have been investigated. SmNi{sub 4}B, SmNi{sub 3}MnB, SmNi{sub 3}FeB, SmNi{sub 3}CoB and SmNi{sub 3}CuB show ferromagnetic ordering at 40 K, 210 K, 322 K, 90 K and 57 K and field sensitive metamagnetic-like transitions at 15 K, 100 K, 185 K, 55 K and 15 K in a magnetic field of 10 kOe, respectively. The magnetocaloric effects of SmNi{sub 3}TB (T=Mn–Cu) were calculated in terms of isothermal magnetic entropy change (ΔS{sub m}). The magnetic entropy ΔS{sub m} reaches value of –0.94 J/kg K at 40 K for SmNi{sub 4}B, –1.5 J/kg K at 205 K for SmNi{sub 3}MnB, –0.54 J/kg K at 320 K for SmNi{sub 3}FeB, –0.49 J/kg K at 90 K for SmNi{sub 3}CoB and –0.54 J/kg K at 60 K for SmNi{sub 3}CuB in field change of 0–50 kOe around the Curie temperature. They show positive ΔS{sub m} of +0.71 J/kg K at ~10 K for SmNi{sub 4}B, +1.69 J/kg K at 30 K for SmNi{sub 3}MnB, +0.89 J/kg K at 110 K for SmNi{sub 3}FeB, +1.08 J/kg K at 25 K for SmNi{sub 3}CoB and +1.12 J/kg K at 10 K for SmNi{sub 3}CuB in field change of 0–50 kOe around the low temperature metamagnetic-like transition. Below the field induced transition temperature (change of magnetic structure), SmNi{sub 3}TB (T=Mn–Cu) exhibits giant magnetic coercivity of 74 kOe at 5 K for SmNi{sub 4}B, 69 kOe at 20 K (90 kOe at 10 K) for SmNi{sub 3}MnB, 77 kOe at 60 K for SmNi{sub 3}FeB, 88 kOe at 20 K for SmNi{sub 3}CoB and 52 kOe at 5 K for SmNi{sub 3}CuB. - Highlights: • YNi{sub 4}B-type SmNi{sub 3}{Mn, Fe, Co, Ni, Cu}B exhibit the Curie points at 39–322 K. • SmNi{sub 3}{Mn, Fe, Co, Ni, Cu}B show field induced transition at 15–185 K. • SmNi{sub 3}MnB shows huge magnetic hysteresis with coercive field of 69 kOe at 20 K. • SmNi{sub 3}FeB shows huge magnetic hysteresis with coercive field of 77 kOe at 60 K. • SmNi{sub 3}CoB shows giant coercive

  13. Study of fluorine doped (Nb,Ir)O{sub 2} solid solution electro-catalyst powders for proton exchange membrane based oxygen evolution reaction

    Energy Technology Data Exchange (ETDEWEB)

    Kadakia, Karan Sandeep [Chemical and Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Jampani, Prashanth H., E-mail: pjampani@pitt.edu [Bioengineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Velikokhatnyi, Oleg I.; Datta, Moni Kanchan [Bioengineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Center for Complex Engineered Multifunctional Materials, University of Pittsburgh, PA 15261 (United States); Patel, Prasad [Chemical and Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Chung, Sung Jae [Mechanical Engineering and Materials Science, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Park, Sung Kyoo [Bioengineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Poston, James A.; Manivannan, Ayyakkannu [US Department of Energy, National Energy Technology Laboratory, Morgantown, WV 26507 (United States); Kumta, Prashant N. [Chemical and Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Bioengineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Center for Complex Engineered Multifunctional Materials, University of Pittsburgh, PA 15261 (United States); Mechanical Engineering and Materials Science, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Department of Oral Biology, School of Dental Medicine, University of Pittsburgh, PA 15217 (United States)

    2016-10-15

    Graphical abstract: High surface area (∼300 m{sup 2}/g) nanostructured powders of nominal composition (Nb{sub 1−x}Ir{sub x})O{sub 2} and (Nb{sub 1−x}Ir{sub x})O{sub 2}:10F have been synthesized and tested as oxygen evolution electro-catalysts for PEM based water electrolysis using a simple two-step chemical synthesis procedure. Superior electrochemical activity was demonstrated by fluorine doped compositions of (Nb{sub 1−x}Ir{sub x})O{sub 2} with an optimal composition (Nb{sub 0.75}Ir{sub 0.25})O{sub 2}:10F (x = 0.25) demonstrating on-par performance with commercial hydrated IrO{sub 2} and nanostructured in-house chemically synthesized IrO{sub 2}. Using first principles calculations, the electronic structure modification resulting in ∼75 at.% reduction (experimentally observed) in noble metal content without loss in catalytic performance and stability has been established. - Highlights: • (Nb{sub 1−x}Ir{sub x})O{sub 2}:10F nanopowder electrocatalysts have been wet chemically synthesized. • (Nb{sub 0.75}Ir{sub 0.25})O{sub 2}:10F exhibits superior electrochemical activity than pure IrO{sub 2}. • Stability of the (Nb,Ir)O{sub 2}:10F nanomaterials is comparable to pure (Nb,Ir)O{sub 2}. • High surface area F doped (Nb,Ir)O{sub 2} are promising OER anode electro-catalysts. - Abstract: High surface area (∼300 m{sup 2}/g) nanostructured powders of (Nb{sub 1−x}Ir{sub x})O{sub 2} and (Nb{sub 1−x}Ir{sub x})O{sub 2}:10F (∼100 m{sup 2}/g) have been examined as promising oxygen evolution reaction (OER) electro-catalysts for proton exchange membrane (PEM) based water electrolysis. Nb{sub 2}O{sub 5} and 10 wt.% F doped Nb{sub 2}O{sub 5} powders were prepared by a low temperature sol-gel process which were then converted to solid solution (Nb,Ir)O{sub 2} and 10 wt.% F doped (Nb,Ir)O{sub 2} [(NbIr)O{sub 2}:10F] electro-catalysts by soaking in IrCl{sub 4} followed by heat treatment in air. Electro-catalyst powders of optimal composition (Nb{sub 0.75}Ir

  14. Magnetic behavior of solid solutions REMe0.50Mn0.50O3 (RE = Y, La, Pr, Nd, Eu, Gd, Er ; Me = Ni,Co

    Directory of Open Access Journals (Sweden)

    Tartaj, J.

    2008-06-01

    Full Text Available Partial substitution of Mn by a divalent metal in rare-earth manganites REMexMn1 xO3 results in the simultaneous presence of Mn3+ and Mn4+. The RE sublattice has its own properties and can interact with the local field imposed by the ferromagnetic Mn network. Its orientation differs depending on the RE nature, adopting a parallel direction with respect to the local field, or it may align in opposite direction, resulting in uncompensated antiferromagnetic structure. For divalent elements (e.g., Ni2+, the solid solution is limited to RENi2+0.5Mn4+0.5O3 ; at this frontier composition, the ferromagnetic superexchange Ni2+-O-Mn4+ interactions are optimized. For Me = Co, this limit can be extended, meaning that part of cobalt takes a 3+ state ; in this case, presence of Co3+ modifies the magnetic coupling, leading to qualitatively different behaviours during the ZFC/FC cycles. In this work, we have chosen the specific composition REMe0.50Mn0.50O3 for which the strongest magnetic interactions are expected, emphasizing the results obtained for Me = Ni and Co and comparing various rare-earth elements (RE = Y, La, Pr, Nd, Eu, Gd and Er. As expected from the general behaviour of the series (RE,CaMnO3, we find that in the RE(Mn,MeO3, the larger the RE ionic radius, the highest the transition temperature, reaching 235 K in LaCo0.50Mn0.50O3 compared to 68 K in ErCo0.50Mn0.50O3.La sustitución parcial de Mn por un catión divalente en manganitas de tierras raras TRMexMn1 xO3 induce la presencia simultánea de Mn3+ y Mn4+. La subred TR tiene sus propiedades intrínsecas y puede interactuar con el campo local impuesto por la red ferromagnética del Mn. Su orientación difiere dependiendo de la naturaleza de la TR, adoptando una dirección paralela con respecto al campo local, o puede alinearse en sentido opuesto, produciendo una estructura antiferromagnética no compensada. Para cationes divalentes (Ni2+, la solución sólida está limitada a TRNi2+0.5Mn4+0.5O3

  15. Search for V H and Technicolor Producion in the qqbb Final State Using the RunII DØ Detector

    Energy Technology Data Exchange (ETDEWEB)

    Clutter, Justace R. [Univ. of Kansas, Lawrence, KS (United States)

    2010-04-01

    A search for dijet resonance production in a four-jet all-hadronic final state from the DØ detector at Fermilab’s Tevatron is presented. The data set, acquired at a p$\\bar{p}$ center-of-mass energy of √s = 1.96 TeV, contains primarily multijet events and represents approximately 1 fb-1 of data. The cross section limits for associated Higgs production and Technicolor pro- cesses are determined through a background subtraction method using data to estimate the background. This four-jet channel is potentially very powerful, but is extremely challenging due to the large multijet background from QCD processes. Background rejection is performed by utilizing b-tagging, pre-selection cuts, a multi-variate boosted decision tree discriminant, and the correlated information contained in the M(bb) and M(jj) dijet invariant masses. The search for V H (WH+ZH) processes yields a 95% confidence level observed upper limit of 20.4 pb on the VH cross section for a Higgs mass of 115 GeV/c2. Additionally, a 95% confidence level observed upper limit of 16.7 pb was set for a Higgs boson mass of 125 GeV/c2 and 24.6 pb was set for a Higgs boson mass of 135 GeV/c2. The same data set was used to place limits on the Technicolor process ρTC → WπTC where the technirho mass was fixed to 240 GeV/c2. For a technipion mass of 115 GeV/c2 we find a 95% confidence level observed upper limit on the cross section of 49 pb. The technipion masses of 125 GeV/c2 and 140 GeV/c2, the 95% confidence level observed upper limits are 57 pb and 71 pb, respectively.

  16. Microstructural characterization of Mg–Al–Sr alloys

    Directory of Open Access Journals (Sweden)

    M. Aljarrah et al

    2007-01-01

    Full Text Available The microstructural details of fourteen Mg–Al–Sr alloys were investigated in the as-cast form by a combination of scanning electron microscopy/energy dispersive spectrometer (SEM/EDS analysis and quantitative electron probe microanalysis (EPMA. The heat transfer method coupled with the DSC measurement has been utilized to determine the solidification curves of the alloys. The morphology and the chemical composition of the phases were characterized. The microstructure of the alloys is primarily dominated by (Mg and (Al4Sr. In the present investigation, ternary solid solubility of three binary compounds extended into the ternary system has been reported and denoted as: (Al4Sr, (Mg17Sr2 and (Mg38Sr9. The (Al4Sr phase is a substitutional solid solution represented by MgxAl4−xSr and has a plate-like structure. The maximum solubility of Al in Mg17Sr2 was found to be 21.3 at%. It was also observed that Mg38Sr9 dissolved 12.5 at% Al.

  17. The Effect of Milling Time on the Microstructural Characteristics and Strengthening Mechanisms of NiMo-SiC Alloys Prepared via Powder Metallurgy.

    Science.gov (United States)

    Yang, Chao; Muránsky, Ondrej; Zhu, Hanliang; Thorogood, Gordon J; Avdeev, Maxim; Huang, Hefei; Zhou, Xingtai

    2017-04-06

    A new generation of alloys, which rely on a combination of various strengthening mechanisms, has been developed for application in molten salt nuclear reactors. In the current study, a battery of dispersion and precipitation-strengthened (DPS) NiMo-based alloys containing varying amounts of SiC (0.5-2.5 wt %) were prepared from Ni-Mo-SiC powder mixture via a mechanical alloying (MA) route followed by spark plasma sintering (SPS) and rapid cooling. Neutron Powder Diffraction (NPD), Electron Back Scattering Diffraction (EBSD), and Transmission Electron Microscopy (TEM) were employed in the characterization of the microstructural properties of these in-house prepared NiMo-SiC DPS alloys. The study showed that uniformly-dispersed SiC particles provide dispersion strengthening, the precipitation of nano-scale Ni₃Si particles provides precipitation strengthening, and the solid-solution of Mo in the Ni matrix provides solid-solution strengthening. It was further shown that the milling time has significant effects on the microstructural characteristics of these alloys. Increased milling time seems to limit the grain growth of the NiMo matrix by producing well-dispersed Mo₂C particles during sintering. The amount of grain boundaries greatly increases the Hall-Petch strengthening, resulting in significantly higher strength in the case of 48-h-milled NiMo-SiC DPS alloys compared with the 8-h-milled alloys. However, it was also shown that the total elongation is considerably reduced in the 48-h-milled NiMo-SiC DPS alloy due to high porosity. The porosity is a result of cold welding of the powder mixture during the extended milling process.

  18. Characterization of phase development in non-isothermally annealed mould-cast and heat-treated Al-Mn-Sc-Zr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Vlach, M., E-mail: martin.vlach@mff.cuni.cz; Stulikova, I.; Smola, B.; Zaludova, N.

    2010-12-15

    The effect of Mn addition on microstructure and mechanical properties during isochronal annealing in the temperature range of 20 deg. C - 570 deg. C of the mould-cast and heat-treated Al-Sc-Zr alloys with a various content of Mn and Zr was studied. The electrical resistometry together with the microhardness (HV0.3) measurements were compared to microstructure development. The microstructure development was examined by scanning electron microscopy, transmission electron microscopy and electron diffraction. Relative resistivity changes and the microhardness of the mould-cast and heat-treated Al-Mn-Sc-Zr alloys exhibit similar dependence on annealing temperature. Precipitation of the Al{sub 3}Sc particles is responsible for the peak microhardness in all these alloys. The microhardness decrease is slightly delayed during the isochronal annealing and during the high temperature heat treatment in the mould-cast alloy with the higher Zr-content due to a higher oversaturation of Zr. The decomposition sequence of the oversaturated solid solution of the studied Al-Mn-Sc-Zr alloys is compatible with the recently published decomposition sequence of the Al-Sc-Zr system and also with the formation of Mn,Fe-containing particles. It seems very probable that the addition of Mn does not influence the decomposition of solid solution of the ternary Al-Sc-Zr system. - Research Highlights: {yields} Al{sub 3}Sc particles are responsible for the peak microhardness in all the studied alloys. {yields} The microhardness decrease is delayed in the alloy with the higher Zr-content. {yields} The peak hardening of the heat-treated alloys is shifted to higher temperatures. {yields} Mn does not influence the decomposition sequence of the Al-Sc-Zr system.

  19. The Effect of Milling Time on the Microstructural Characteristics and Strengthening Mechanisms of NiMo-SiC Alloys Prepared via Powder Metallurgy

    Directory of Open Access Journals (Sweden)

    Chao Yang

    2017-04-01

    Full Text Available A new generation of alloys, which rely on a combination of various strengthening mechanisms, has been developed for application in molten salt nuclear reactors. In the current study, a battery of dispersion and precipitation-strengthened (DPS NiMo-based alloys containing varying amounts of SiC (0.5–2.5 wt % were prepared from Ni-Mo-SiC powder mixture via a mechanical alloying (MA route followed by spark plasma sintering (SPS and rapid cooling. Neutron Powder Diffraction (NPD, Electron Back Scattering Diffraction (EBSD, and Transmission Electron Microscopy (TEM were employed in the characterization of the microstructural properties of these in-house prepared NiMo-SiC DPS alloys. The study showed that uniformly-dispersed SiC particles provide dispersion strengthening, the precipitation of nano-scale Ni3Si particles provides precipitation strengthening, and the solid-solution of Mo in the Ni matrix provides solid-solution strengthening. It was further shown that the milling time has significant effects on the microstructural characteristics of these alloys. Increased milling time seems to limit the grain growth of the NiMo matrix by producing well-dispersed Mo2C particles during sintering. The amount of grain boundaries greatly increases the Hall–Petch strengthening, resulting in significantly higher strength in the case of 48-h-milled NiMo-SiC DPS alloys compared with the 8-h-milled alloys. However, it was also shown that the total elongation is considerably reduced in the 48-h-milled NiMo-SiC DPS alloy due to high porosity. The porosity is a result of cold welding of the powder mixture during the extended milling process.

  20. Microstructure-sensitive modelling of dislocation creep in polycrystalline FCC alloys: Orowan theory revisited

    Energy Technology Data Exchange (ETDEWEB)

    Galindo-Nava, E.I., E-mail: eg375@cam.ac.uk; Rae, C.M.F.

    2016-01-10

    A new approach for modelling dislocation creep during primary and secondary creep in FCC metals is proposed. The Orowan equation and dislocation behaviour at the grain scale are revisited to include the effects of different microstructures such as the grain size and solute atoms. Dislocation activity is proposed to follow a jog-diffusion law. It is shown that the activation energy for cross-slip E{sub cs} controls dislocation mobility and the strain increments during secondary creep. This is confirmed by successfully comparing E{sub cs} with the experimentally determined activation energy during secondary creep in 5 FCC metals. It is shown that the inverse relationship between the grain size and dislocation creep is attributed to the higher number of strain increments at the grain level dominating their magnitude as the grain size decreases. An alternative approach describing solid solution strengthening effects in nickel alloys is presented, where the dislocation mobility is reduced by dislocation pinning around solute atoms. An analysis on the solid solution strengthening effects of typical elements employed in Ni-base superalloys is also discussed. The model results are validated against measurements of Cu, Ni, Ti and 4 Ni-base alloys for wide deformation conditions and different grain sizes.

  1. Microstructure refinement and hardening of Ag–20 wt.%Cu alloy by rapid solidification

    Energy Technology Data Exchange (ETDEWEB)

    Lussana, Danilo, E-mail: danilo.lussana@unito.it [Dipartimento di Chimica and NIS, Università di Torino, Torino (Italy); Castellero, Alberto [Dipartimento di Chimica and NIS, Università di Torino, Torino (Italy); Vedani, Maurizio [Dipartimento di Meccanica, Politecnico di Milano, Milano (Italy); Ripamonti, Dario; Angella, Giuliano [Istituto IENI-CNR, Unità territoriale di Milano, Milano (Italy); Baricco, Marcello [Dipartimento di Chimica and NIS, Università di Torino, Torino (Italy)

    2014-12-05

    Highlights: • Ag80–Cu20 alloy were rapidly solidified by planar flow casting technique. • A significant refinement of the eutectic microstructure has been obtained. • A refinement of the primary silver-rich phase has been achieved with high cooling rate. • The hardness increases up to the 150% of the value of an annealed sample. - Abstract: Ag–20 wt.%Cu (wt%) hypoeutectic alloy has been rapidly solidified by means of planar flow casting technique. Two fcc solid solutions have been identified by X-ray diffraction. Microstructures have been observed by electron microscopy. A refinement of the eutectic microstructure, as well as of the Ag-rich primary phase, has been observed for high quenching rates, leading to a hardness value up to 235 Vickers. The lattice parameter and phase fraction of the Ag-rich solid solution increase as a function of quenching rates (i.e. wheel speed). The solidification processes occurring during rapid quenching have been described on the basis of thermodynamic and kinetic arguments.

  2. Influence of strain rate on the twin and slip activity of a magnesium alloy containing neodymium

    Energy Technology Data Exchange (ETDEWEB)

    Dudamell, N.V. [IMDEA Materials Institute, C/Eric Kandel 2, 28906 Getafe, Madrid (Spain); Hidalgo-Manrique, P., E-mail: paloma.hidalgo@imdea.org [IMDEA Materials Institute, C/Eric Kandel 2, 28906 Getafe, Madrid (Spain); Chakkedath, A.; Chen, Z.; Boehlert, C.J. [Michigan State University, East Lansing, MI 48824-1226 (United States); Gálvez, F. [ETS Ingenieros de Caminos, Universidad Politécnica de Madrid, 28040 Madrid (Spain); Yi, S.; Bohlen, J.; Letzig, D. [Magnesium Innovation Centre, Helmholtz-Zentrum Geesthacht, 21502 Geesthacht (Germany); Pérez-Prado, M.T. [IMDEA Materials Institute, C/Eric Kandel 2, 28906 Getafe, Madrid (Spain)

    2013-10-20

    The mechanical behavior of an extruded magnesium–manganese alloy containing 1 wt% of neodymium (MN11) has been investigated at temperatures ranging from room temperature to 400 °C at both quasi-static and dynamic rates. Conventional ex-situ tests, carried out in compression along the extrusion axis (EA), have been combined with in-situ tests in a scanning electron microscope (SEM) in order to elucidate the effect of a rare earth (RE) addition on the dominant deformation mechanisms. An unusually large activity of twinning was observed at room temperature in a wide range of quasi-static rates. Furthermore, the twinning activity has been found to increase at temperatures around 250 °C, where clear signs of dynamic strain aging (DSA) are also apparent. The enhanced twinning activity compared to conventional Mg alloys, not containing RE elements, is attributed to an increase in the critical resolved shear stress of basal slip (CRSS{sub basal}) due to the presence of intermetallic RE-containing particles and to the Nd atoms in solid solution. The surprising decrease of the twinning activity at dynamic rates (∼10{sup 3} s{sup −1}) may be explained by a decrease in the CRSS{sub basal} as the intermetallic RE-containg particles and the Nd solid solution strengthening become less effective with increasing strain rate.

  3. Synthesis of Al₂Ca Dispersoids by Powder Metallurgy Using a Mg-Al Alloy and CaO Particles.

    Science.gov (United States)

    Fujita, Junji; Umeda, Junko; Kondoh, Katsuyoshi

    2017-06-28

    The elemental mixture of Mg-6 wt %Al-1 wt %Zn-0.3 wt %Mn (AZ61B) alloy powder and CaO particles was consolidated by an equal-channel angular bulk mechanical alloying (ECABMA) process to form a composite precursor. Subsequently, the precursor was subjected to a heat treatment to synthesize fine Al₂Ca particles via a solid-state reaction between the Mg-Al matrix and CaO additives. Scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS) and electron probe micro-analysis on the precursor indicated that 4.7-at % Al atoms formed a supersaturated solid solution in the α-Mg matrix. Transmission electron microscopy-EDS and X-ray diffraction analyses on the AZ61B composite precursor with 10-vol % CaO particles obtained by heat treatment confirmed that CaO additives were thermally decomposed in the Mg-Al alloy, and the solid-soluted Ca atoms diffused along the α-Mg grain boundaries. Al atoms also diffused to the grain boundaries because of attraction to the Ca atoms resulting from a strong reactivity between Al and Ca. As a result, needle-like (Mg,Al)₂Ca intermetallics were formed as intermediate precipitates in the initial reaction stage during the heat treatment. Finally, the precipitates were transformed into spherical Al₂Ca particles by the substitution of Al atoms for Mg atoms in (Mg,Al)₂Ca after a long heat treatment.

  4. Influence of Processing on the Microstructure and Properties of CoCrMoSi Alloy PTA Coatings

    Directory of Open Access Journals (Sweden)

    R.G Bohatch

    2015-06-01

    Full Text Available AbstractWear performance as well as the low toughness of CoCrMoSi alloys is associated with the presence of Laves phase. In light of this, alloying elements have been altered in order to reduce the brittleness of newly-cast alloys. This study evaluated coatings by Plasma Transferred Arc (PTA with different interactions with the AISI 316L substrate. The higher the dilution, it was hypothesized, the higher Iron, Chromium and Nickel contents proceeding from substrate and, therefore, the lower hard Laves phase fraction. Coatings were characterized by light and scanning electron microscopy, X-ray diffraction and Vickers hardness. Wear behavior was assessed by pin-on-disc and ball-on-flat tests. Laves phase and Cobalt solid solution eutectic lamellar microstructure was observed for coating processed with 120A (18% dilution. The chemical composition was displaced to hypoeutectic, showing Cobalt solid solution dendrites and interdendrictic eutectic lamellar for the coatings processed with higher current intensity (150 / 180A, due to the higher interaction with the substrate (26 / 38% dilution. Dilution increased with the deposition current, causing hardness to decrease from 702 – 526 HV0.5. Wear mass loss rate increased by up to 41.7% and friction coefficient (μ ranged from 0.45 – 1.06 as the chemical composition changed.

  5. Comparison of joining processes for Haynes 230 nickel based super alloy

    Science.gov (United States)

    Williston, David Hugh

    Haynes 230 is a nickel based, solid-solution strengthened alloy that is used for high-temperature applications in the aero-engine and power generation industries. The alloy composition is balanced to avoid precipitation of undesirable topologically closed-packed (TCP) intermetallic phases, such as Sigma, Mu, or Laves-type, that are detrimental to mechanical and corrosion properties. This material is currently being used for the NASA's J2X upper stage rocket nozzle extension. Current fabrication procedures use fusion welding processes to join blanks that are subsequently formed. Cracks have been noted to occur in the fusion welded region during the forming operations. Use of solid state joining processes, such as friction stir welding are being proposed to eliminate the fusion weld cracks. Of interest is a modified friction stir welding process called thermal stir welding. Three welding process: Gas Metal Arc Welding (GMAW), Electron Beam Welding (EBW), and Thermal Stir Welding (TSWing) are compared in this study.

  6. Ultrasonic-promoted rapid TLP bonding of fine-grained 7034 high strength aluminum alloys.

    Science.gov (United States)

    Guo, Weibing; Leng, Xuesong; Luan, Tianmin; Yan, Jiuchun; He, Jingshan

    2017-05-01

    High strength aluminum alloys are extremely sensitive to the thermal cycle of welding. An ultrasonic-promoted rapid TLP bonding with an interlayer of pure Zn was developed to join fine-grained 7034 aluminum alloys at the temperature of lower 400°C. The oxide film could be successfully removed with the ultrasonic vibration, and the Al-Zn eutectic liquid phase generated once Al and Zn contacted with each other. Longer ultrasonic time can promote the diffusion of Zn into the base metal, which would shorten the holding time to complete isothermal solidification. The joints with the full solid solution of α-Al can be realized with the ultrasonic action time of 60s and holding time of only 3min at 400°C, and the shear strength of joints could reach 223MPa. The joint formation mechanism and effects of ultrasounds were discussed in details. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Magnetoelectric and electric measurements of the (1-x)BiFeO{sub 3}–(x)Pb(Fe{sub 1/2}Nb{sub 1/2})O{sub 3} solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Bochenek, D., E-mail: dariusz.bochenek@us.edu.pl [University of Silesia, Faculty of Computer Science and Material Science, Institute of Technology and Mechatronics, 12, Żytnia St., 41–200, Sosnowiec (Poland); Niemiec, P. [University of Silesia, Faculty of Computer Science and Material Science, Institute of Technology and Mechatronics, 12, Żytnia St., 41–200, Sosnowiec (Poland); Guzdek, P. [Institute of Electron Technology Cracow Division, 39, Zabłocie St., Cracow, 30-701 (Poland); Wzorek, M. [Institute of Electron Technology, Al. Lotników 32/46, 02-668, Warsaw (Poland)

    2017-07-01

    In the paper ferro–electro–magnetic (1-x)BiFeO{sub 3}-(x)Pb(Fe{sub 1/2}Nb{sub 1/2})O{sub 3} (BF-PFN) solid solutions were obtained (containing the percentage BF/PFN: 60/40 and 70/30). Individual components of the solid solution were prepared by follows methods: synthesizing a powder BF was performed by calcining the simple oxides (Bi{sub 2}O{sub 3}, Fe{sub 2}O{sub 3}), and synthesizing a powder PFN was carried out by calcining a mixture of complex oxides (FeNbO{sub 4}, PbO). Compaction of synthesized and mixed BiFeO{sub 3}, PbFe{sub 1/2}Nb{sub 1/2}O{sub 3} powders was carried out by free sintering methods. X–ray, microstructure, dielectric, magnetic and magnetoelectric studies, DC electrical conductivity and electrical hysteresis loop were carried out. Magnetoelectric effect measurements performed at room temperature showed coupling between electric and magnetic subsystem of the BF–PFN solid solutions. - Highlights: • BF-PFN samples have a densely packed microstructure, with well crystallized grains. • Bi atoms possibly migrate from BF toward PFN component during sintering. • BF-PFN have a diffuse character of the ferroelectric–paraelectric phase transition. • Magnetoelectric coefficient (α{sub ME}) for BF-PFN is higher, than for pure BF. • The α{sub ME} for BF-PFN is about three times higher than for 0.75BiFeO{sub 3}–0.25BaTiO{sub 3}.

  8. Synthesis, second-harmonic generation (SHG), and photoluminescence (PL) properties of noncentrosymmetric bismuth selenite solid solutions, Bi2-xLnxSeO5 (Ln = La and Eu; x = 0-0.3)

    Science.gov (United States)

    Qi, Hai-Xin; Jo, Hongil; Oh, Seung-Jin; Ok, Kang Min

    2018-02-01

    A series of La3+ or Eu3+-doped noncentrosymmetric (NCS) bismuth selenite solid solutions, Bi2-xLnxSeO5 (x = 0.1, 0.2, and 0.3), have been successfully synthesized via standard solid-state reactions under vacuum with Bi2O3, La2O3 (or Eu2O3), and SeO2 as starting materials. Crystal structures and phase purities of the resultant materials were thoroughly characterized by powder X-ray diffraction using the Rietveld method. The results clearly show that the reported materials crystallize in the orthorhombic space group, Abm2 (No. 39), and exhibit pseudo-three-dimensional frameworks consisting of BiO3, BiO5, and SeO3 polyhedra that share edges and corners. Detailed diffraction studies indicate that the cell volume of Bi2-xLnxSeO5 decreases with an increasing amount of Ln3+ on the Bi3+ sites. However, no ordering between Ln3+ and Bi3+ was observed in the Bi2-xLnxSeO5 solid solutions. Powder second-harmonic generation (SHG) measurements, using 1064 nm radiation, reveal that SHG efficiencies of Bi2-xLnxSeO5 solid solutions continuously decrease as more Ln3+ cations are added to the sites of polarizable Bi3+ cations. Photoluminescence (PL) measurements on Bi2-xEuxSeO5 exhibit three specific emission peaks at 592, 613, and 702 nm (5D0 → 7F1, 2, 4) owing to the 4f-4f intrashell transitions of Eu3+ ions.

  9. Local polar structure and multiferroic properties of (1−x)Bi{sub 0.9}Dy{sub 0.1}FeO{sub 3}−xPbTiO{sub 3} solid solution

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Jian [Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi' an Jiaotong University, Xi' an 710049 (China); Department of Chemistry and 4D LABS, Simon Fraser University, Burnaby, British Columbia, V5A 1S6 (Canada); Wu, Hua [Department of Applied Physics, Donghua University, Ren Min Road 2999, Songjiang District, 201620 Shanghai (China); Department of Chemistry and 4D LABS, Simon Fraser University, Burnaby, British Columbia, V5A 1S6 (Canada); Ren, Wei, E-mail: zye@sfu.ca, E-mail: wren@mail.xjtu.edu.cn [Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi' an Jiaotong University, Xi' an 710049 (China); Ye, Zuo-Guang, E-mail: zye@sfu.ca, E-mail: wren@mail.xjtu.edu.cn [Department of Chemistry and 4D LABS, Simon Fraser University, Burnaby, British Columbia, V5A 1S6 (Canada); Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi' an Jiaotong University, Xi' an 710049 (China)

    2014-08-14

    The multiferroic (1–x)[0.9BiFeO{sub 3}–0.1DyFeO{sub 3}]–xPbTiO{sub 3} (BDF–xPT) solid solution with compositions around the morphotropic phase boundary (x = 0.25, 0.28, 0.31, 0.34, and 0.37) has been synthesized in the form of ceramics. The phase symmetry, microstructure, ferroelectricity, piezoresponse, and ferromagnetic properties have been characterized by various techniques. It is found that, with increasing content of lead titanate from x = 0.25 to x = 0.37, the grain size increases and the ferroelectric property is improved. The ferroelectric performance is further enhanced by the introduction of an excess amount (2%) of TiO{sub 2} or by sintering in oxygen atmosphere, which reduces the leakage. The local polar structure is imaged by piezoresponse force microscopy. Both the out-of-plane and in-plane images reveal distinct ferroelectric domain structures, with the amplitude and the average domain size decreasing with the increase of lead titanate amount. Compared with the (1–x)BiFeO{sub 3}–xPbTiO{sub 3} binary solid solution of about the same concentration of PT, the magnetic properties are enhanced in BDF–xPT due to the presence of dysprosium, as demonstrated by the ferromagnetic hysteresis loops displayed at room temperature and at 10 K, but the remnant magnetization decreases with increasing PT content. The simultaneous presence of ferroelectricity and ferromagnetism entitles the BDF–xPT solid solution a room-temperature multiferroic material.

  10. BiOCl{sub x}Br{sub y}I{sub z} (x + y + z = 1) solid solutions with controllable band gap and highly enhanced visible light photocatalytic performances

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xiuguo; Zhang, Yangyang; Li, Chunmei; Zhang, Zhifeng; Peng, Zheng; Si, Huayan; Zhang, Jianmin [School of Materials Science and Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043 (China); Li, Yanting, E-mail: yantingcn@stdu.edu.cn [School of Materials Science and Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043 (China); Hebei Provincial Key Laboratory of Traffic Engineering materials, Shijiazhuang Tiedao University, Shijiazhuang 050043 (China)

    2015-07-25

    Highlights: • BiOCl{sub x}Br{sub y}I{sub z} solid solutions were prepared by hydrolysis method. • Band gap of the solid solutions can be controllable by adjusting the molar ratio of halogen ions. • The samples show higher visible light photocatalytic activity than pure BiOX. • Orbital diversification of VB is beneficial to separating the holes and electrons effectively. • The mechanisms are discussed by active species trapping and band theory. - Abstract: A series of BiOCl{sub x}Br{sub y}I{sub z} solid solutions with controllable band gap and highly enhanced visible light photocatalytic performances were synthesized by a simple hydrolysis method. The samples were characterized by X-ray powder diffraction, UV–vis diffuse reflectance spectra, scanning electron microscope, high-resolution transmission electron microscopy and Brunauer–Emmett–Teller analysis. By adjusting the molar ratio of halogen ions, the band gap of BiOCl{sub x}Br{sub y}I{sub z} could be controllable to the suitable value for a photocatalytic reaction. Especially, BiOCl{sub x}Br{sub y}I{sub z} with a 1:1:2 molar ratio of Cl, Br to I showed the highest visible light photocatalytic activity for the degradation of methyl orange than individual BiOX systems. The degradation efficiency could reach over 90% within 60 min. The possible mechanism of photogenerated carrier transfer and higher photocatalytic activity was analyzed by active species trapping and energy band theory.

  11. Photocatalytical water decomposition on visible light-driven solid-solution compounds K{sub 4}Ce{sub 2}Ta{sub 10-x}Nb{sub x}O{sub 30} (x = 0-10)

    Energy Technology Data Exchange (ETDEWEB)

    Tian Mengkui, E-mail: tianmk@hotmail.com [School of Chemistry and Chemical Engineering, Guizhou University, Guiyang, Guizhou (China); Shangguan Wenfeng, E-mail: shanguan@sjtu.edu.cn [Centre for Combustion and Environmental Protection, Shanghai Jiao Tong University, Shanghai 200030 (China)

    2012-01-05

    Highlights: Black-Right-Pointing-Pointer Visible light driven solid-solution compounds K{sub 4}Ce{sub 2}Ta{sub 10-x}Nb{sub x}O{sub 30} (x = 0-10) were synthesized by solid state reaction. Black-Right-Pointing-Pointer These solid-solution compounds demonstrated water decomposition activities under visible light irradiation. Black-Right-Pointing-Pointer Their electronic structures were studied based on the first principle calculation. Black-Right-Pointing-Pointer The proposed band structure has good agreement with their absorption properties and photocatalytic activities. - Abstract: A series of single phase solid-solution K{sub 4}Ce{sub 2}Ta{sub 10-x}Nb{sub x}O{sub 30} (x = 0-10) photocatalysts were synthesized by conventional high temperature solid state reaction. Their UV-vis diffuse reflectance spectra showed their absorbance edges shifted to long wavelength zone consistently with the increase of the amount of Nb for substituting Ta in these compounds, and the onsets of absorbance edges ranging from about 540 nm to 690 nm, corresponding to bandgap energy of 1.8-2.3 eV. These series of photocatalysts possess appropriate band gap (ca. 1.8-2.3 eV) and chemical level to use solar energy to decompose water into H{sub 2}, and the photocatalytical activities under visible light ({lambda} > 420 nm) demonstrated that the activities decreased correspondingly with the increase of the amount of Nb in these compounds, which is regarded as the result of the differences of their band structures. Furthermore, the photocatalytical activities and the photophysical properties of these visible light-driven photocatalysts K{sub 4}Ce{sub 2}Ta{sub 10-x}Nb{sub x}O{sub 30} (x = 0-10) were bridged by the first principle calculation based on Density Functional Theory with General Gradient Approximation and Plane-wave Pseudopotential methods.

  12. Effects of alloying elements on the formation of < c >-component loops in Zr alloy Excel under heavy ion irradiation.

    Energy Technology Data Exchange (ETDEWEB)

    Idrees, Yasir; Francis, Elisabeth M.; Yao, Zhongwen; Korinek, Andreas; Kirk, Marquis A.; Sattari, Mohammad; Preuss, Michael; Daymond, M. R.

    2015-05-14

    We report here the microstructural changes occurring in the zirconium alloy Excel (Zr-3.5 wt% Sn-0.8Nb-0.8Mo-0.2Fe) during heavy ion irradiation. In situ irradiation experiments were conducted at reactor operating temperatures on two Zr Excel alloy microstructures with different states of alloying elements, with the states achieved by different solution heat treatments. In the first case, the alloying elements were mostly concentrated in the beta (beta) phase, whereas, in the second case, large Zr-3(Mo,Nb,Fe)(4) secondary phase precipitates (SPPs) were grown in the alpha (alpha) phase by long term aging. The heavy ion induced damage and resultant compositional changes were examined using transmission electron microscopy (TEM) in combination with scanning transmission electron microscope (STEM)-energy dispersive x-ray spectroscopy (EDS) mapping. Significant differences were seen in microstructural evolution between the two different microstructures that were irradiated under similar conditions. Nucleation and growth of < c >-component loops and their dependence on the alloying elements are a major focus of the current investigation. It was observed that the < c >-component loops nucleate readily at 100, 300, and 400 degrees C after a threshold incubation dose (TID), which varies with irradiation temperature and the state of alloying elements. It was found that the TID for the formation of < c >-component loops increases with decrease in irradiation temperature. Alloying elements that are present in the form of SPPs increase the TID compared to when they are in the beta phase solid solution. Dose and temperature dependence of loop size and density are presented. Radiation induced redistribution and clustering of alloying elements (Sn, Mo, and Fe) have been observed and related to the formation of < c >-component loops. It has been shown that at the higher temperature tests, irradiation induced dissolution of precipitates occurs whereas irradiation induced

  13. Binder-jetting 3D printing and alloy development of new biodegradable Fe-Mn-Ca/Mg alloys.

    Science.gov (United States)

    Hong, Daeho; Chou, Da-Tren; Velikokhatnyi, Oleg I; Roy, Abhijit; Lee, Boeun; Swink, Isaac; Issaev, Ilona; Kuhn, Howard A; Kumta, Prashant N

    2016-11-01

    3D printing of various biomaterials including titanium and stainless steel has been studied for treating patients with cranio-maxillofacial bone defect. The potential long term complications with use of inert biometals have opened the opportunities for use of biodegradable metals in the clinical arena. The authors previously reported that binder-jet 3D printing technique enhanced the degradation rates of biodegradable Fe-Mn alloy by creating engineered micropores rendering the system attractive as biodegradable implantable devices. In the present study, the authors employed CALPHAD modeling to systematically study and modify the Fe-Mn alloy composition to achieve enhanced degradation rates. Accordingly, Ca and Mg addition to Fe-35wt% Mn solid solution predicted increase in degradation rates. In order to validate the CALPHAD results, Fe - (35-y)wt% Mn - ywt% X (X=Ca, Mg, and y=0, 1, 2) were synthesized by using high energy mechanical alloying (HEMA). Sintered pellets of Fe-Mn-Ca and Fe-Mn-Mg were then subjected to potentiodynamic polarization (PDP) and live/dead cell viability tests. Sintered pellets of Fe-Mn, Fe-Mn-Ca, and Fe-Mn-Mg also exhibited MC3T3 murine pre-osteoblast cells viability in the live/dead assay results. Fe-Mn and Fe-Mn-1Ca were thus accordingly selected for 3D printing and the results further confirmed enhanced degradation of Ca addition to 3D printed constructs validating the theoretical and alloy development studies. Live/dead and MTT cell viability results also confirmed good cytocompatibility of the 3D-printed Fe-Mn and Fe-Mn-1Ca constructs. Bone grafting is widely used for the treatment of cranio-maxillofacial bone injuries. 3D printing of biodegradable Fe alloy is anticipated to be advantageous over current bone grafting techniques. 3D printing offers the fabrication of precise and tailored bone grafts to fit the patient specific bone defect needs. Biodegradable Fe alloy is a good candidate for 3D printing synthetic grafts to regenerate bone

  14. Microstructure and Mechanical Property of 3003 Aluminum Alloy Joint Brazed with Al-Si-Cu-Zn Filler Metal

    Directory of Open Access Journals (Sweden)

    LI Xiao-qiang

    2016-09-01

    Full Text Available Al-Si-Cu-Zn filler metal was developed to braze 3003 aluminum alloy. The microstructure and fracture surface of the joint were analyzed by XRD, SEM and EDS, and the effects of brazing temperature on microstructure and property of the joint were investigated. The results show that good joints are obtained at brazing temperature of 540-580℃ for 10min. The brazed joint consists of α(Al solid solution, θ(Al2Cu intermetallic compound, fine silicon phase and AlCuFeMn+Si phase in the central zone of brazed seam, and α(Al solid solution and element diffusion layers at both the sides of brazed seam, and the base metal. The room temperature (RT shear fracture of the joint occurs at the interface between the teeth shape α(Al in the diffusion layer and the center zone of brazed seam, which is mainly characterized as brittle cleavage. As the brazing temperature increases, α(Al solid solution crystals in the diffusion zone grow up, and the interfacial bonding of the joint is in the form of interdigitation. Brazing at 560℃ for 10min, the RT shear strength of the joint reaches the maximum value of 92.3MPa, which is about 62.7% of the base material.

  15. Composition of α−Fe nanoparticles precipitated from CuFe alloy studied by hyperfine interactions

    Energy Technology Data Exchange (ETDEWEB)

    Kubániová, Denisa, E-mail: kubaniova@mbox.troja.mff.cuni.cz [Charles University, Faculty of Mathematics and Physics (Czech Republic); Cesnek, Martin, E-mail: martin.cesnek@fjfi.cvut.cz [Czech Technical University, Department of Nuclear Reactors (Czech Republic); Milkovi c, Ondrej [Slovak Academy of Sciences, Institute of Materials Research (Slovakia); Kohout, Jaroslav [Charles University, Faculty of Mathematics and Physics (Czech Republic); Miglierini, Marcel [Czech Technical University, Department of Nuclear Reactors (Czech Republic)

    2016-12-15

    Iron-based nanoparticles prepared by precipitation from solid solution of saturated binary Cu-Fe alloy were studied by transmission electron microscopy, high-energy X-ray diffraction and Mössbauer spectroscopy. The results showed that the investigated as-prepared nanoparticles contained two phases. The major phase was determined as α−Fe and the minor phase as γ−Fe{sub 2}O{sub 3}. Furthermore, additionally annealed samples in Ar protective atmosphere were investigated. Results showed clear decrease in contribution of α−Fe phase and also revealed the presence of various iron oxides (maghemite, magnetite, hematite and wűstite).

  16. Experimental determination of the high temperature heat capacity of a natural xenotime-(Y) solid solution and synthetic DyPO{sub 4} and ErPO{sub 4} endmembers

    Energy Technology Data Exchange (ETDEWEB)

    Gysi, Alexander P., E-mail: agysi@mines.edu [Department of Geology and Geological Engineering, Colorado School of Mines, 1516 Illinois Street, Golden, CO 80401 (United States); Harlov, Daniel [Geoforschungszentrum Potsdam (GFZ), Telegrafenberg, D-14473 Potsdam (Germany); Filho, Deusavan Costa [Department of Geology and Geological Engineering, Colorado School of Mines, 1516 Illinois Street, Golden, CO 80401 (United States); Williams-Jones, Anthony E. [Department of Earth and Planetary Sciences, McGill University, 3450 University St., Montreal, QC H3A 2A7 (Canada)

    2016-03-20

    Highlights: • A new DSC calibration method for minerals of geological interest is described. • The heat capacity of DyPO{sub 4}, ErPO{sub 4} and xenotime-(Y) were reliably determined using DSC. • The excess heat capacity of xenotime-(Y) indicates a non-ideal solution with other HREE. - Abstract: The heat capacity of natural xenotime-(Y) and synthetic DyPO{sub 4} and ErPO{sub 4} crystals was determined by differential scanning calorimetry (DSC) at temperatures of 298.15 K to 868.15 K and a pressure of 0.1 MPa. The aim of the study was to develop a method to accurately measure the isobaric heat capacity (C{sub P}) of rare earth element (REE) phosphates, compare the results to data from adiabatic calorimetric experiments, and evaluate the deviation from ideality of the C{sub P} of the natural xenotime-(Y) solid solution. The measured C{sub P} data (in J mol{sup −1} K{sup −1}) can be described by the relationships: 185.5 − 751.9T{sup −0.5} − 3.261e + 06 T{sup −2} for DyPO{sub 4}; 207.2 − 1661T{sup −0.5} − 5.289e + 05 T{sup −2} for ErPO{sub 4}; and 208 − 1241T{sup −0.5} − 2.493e + 06 T{sup −2} for xenotime-(Y); where T is the temperature in K. The heat capacity data for natural xenotime-(Y) were used to determine the excess function for the solid solution, which yields an excess heat capacity ranging between 7.9 and 10.7%, well within the range of the DSC method used in this study. The experiments indicate that xenotime-(Y) forms a non-ideal solid solution. Future DSC studies will provide important data for developing a solid solution model for the incorporation of REE in xenotime-(Y).

  17. Heat capacity and neutron diffraction studies on the frustrated magnetic Co{sub 2}(OH)(PO{sub 4}){sub 1-x}(AsO{sub 4}){sub x} [0{<=}x{<=}1] solid solution

    Energy Technology Data Exchange (ETDEWEB)

    Pedro, I. de, E-mail: depedrovm@unican.es [CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander (Spain); Departamento de Quimica Inorganica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, 48080 Bilbao (Spain); Rojo, J.M. [Departamento de Quimica Inorganica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, 48080 Bilbao (Spain); Rodriguez Fernandez, J.; Sanchez Marcos, J. [CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander (Spain); Fernandez-Diaz, M.T. [Institut Laue-Langevin, BP 156X, F-38042 Grenoble Cedex (France); Rojo, T. [Departamento de Quimica Inorganica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, 48080 Bilbao (Spain)

    2012-04-15

    The Co{sub 2}(OH)(PO{sub 4}){sub 1-x}(AsO{sub 4}){sub x} [0{<=}x{<=}1] solid solution exhibits a complex magnetic behaviour due to the bond-frustration in its magnetic structure. Heat capaci