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Binary Alloy (binary + alloy)
Selected AbstractsFirst Synthesis of Group-14 Polyanions by Extraction of a Binary Alloy with dmf and a Novel Conformation of the (Ge9,Ge9)6- Dimer: Crystal Structures of [K6(Ge9,Ge9)](dmf)12, [Rb6(Ge9,Ge9)](dmf)12 and [K2.5Cs3.5(Ge9,Ge9)] (dmf)12.CHEMINFORM, Issue 47 2006Anke Nienhaus Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] A Novel Amperometric Transducer Electrode with Iridium-Niobium Binary AlloysELECTROANALYSIS, Issue 20 2009Toru Matsumoto Abstract We have discovered that an Ir-23Nb binary alloy more effectively oxidizes hydrogen peroxide than Ir, Ir-13Nb, Ir-17Nb, Ir-30Nb, Ir-43Nb, Ir-62Nb, or Nb. The oxidation capability was determined via cyclic voltammogram measurements of pH-buffer and hydrogen peroxide. We ascertained that applying a 0.7,V potential produces hydrogen peroxide currents of 9.2,,A/mm2 Ir-23Nb, 5.3,,A/mm2 Ir, 5.1,,A/mm2 Ir-17Nb, 3.7,,A/mm2 Ir-13Nb, 2.0,,A/mm2 Ir-30Nb, 1.5,,A/mm2 Ir-43Nb, 0.6,,A/mm2 Ir-62Nb, and 0.13,,A/mm2 Nb. These results indicate that the effective oxidation of Ir-23Nb for hydrogen peroxide might be due to its fcc+L12 two-phase structure and that Ir-23Nb can be used as an amperometric transducer material. [source] Nanoscale lead and noble gas inclusions in aluminum: Structures and propertiesMICROSCOPY RESEARCH AND TECHNIQUE, Issue 5-6 2004Erik Johnson Abstract Transmission electron microscopy has been used for structural and physical characterization of nanoscale inclusions of lead and noble gases in aluminum. When the inclusion sizes approach nanoscale dimensions, many of their properties are seen to deviate from similar properties in bulk and in most cases the deviations will increase as the inclusion sizes decrease. Binary alloys of lead and noble gases with aluminum are characterized by extremely low mutual solubilities and inclusions will, therefore, exist as practically pure components embedded in the aluminum matrix. Furthermore, the thermal vacancy mobility in aluminum at and above room temperature is sufficiently high to accommodate volume strains associated with the inclusions thus leading to virtually strain free crystals. The inclusions grow in parallel cube alignment with the aluminum matrix and have a cuboctahedral shape, which reflects directly the anisotropy of the interfacial energies. Inclusions in grain boundaries can have single crystalline or bicrystalline morphology that can be explained from a generalized Wulff analysis such as the ,-vector construction. The inclusions have been found to display a variety of nanoscale features such as high Laplace pressure, size-dependent superheating during melting, deviations from the Wulff shape displaying magic size effects, a shape dependence of edge energy, and so on. All these effects have been observed and monitored by TEM using conventional imaging conditions and high-resolution conditions in combination with in-situ analysis at elevated temperatures. Microsc. Res. Tech. 64:356,372, 2004. © 2004 Wiley-Liss, Inc. [source] A Novel Amperometric Transducer Electrode with Iridium-Niobium Binary AlloysELECTROANALYSIS, Issue 20 2009Toru Matsumoto Abstract We have discovered that an Ir-23Nb binary alloy more effectively oxidizes hydrogen peroxide than Ir, Ir-13Nb, Ir-17Nb, Ir-30Nb, Ir-43Nb, Ir-62Nb, or Nb. The oxidation capability was determined via cyclic voltammogram measurements of pH-buffer and hydrogen peroxide. We ascertained that applying a 0.7,V potential produces hydrogen peroxide currents of 9.2,,A/mm2 Ir-23Nb, 5.3,,A/mm2 Ir, 5.1,,A/mm2 Ir-17Nb, 3.7,,A/mm2 Ir-13Nb, 2.0,,A/mm2 Ir-30Nb, 1.5,,A/mm2 Ir-43Nb, 0.6,,A/mm2 Ir-62Nb, and 0.13,,A/mm2 Nb. These results indicate that the effective oxidation of Ir-23Nb for hydrogen peroxide might be due to its fcc+L12 two-phase structure and that Ir-23Nb can be used as an amperometric transducer material. [source] Ab Initio Guided Design of bcc Ternary Mg,Li,X (X,=,Ca, Al, Si, Zn, Cu) Alloys for Ultra-Lightweight ApplicationsADVANCED ENGINEERING MATERIALS, Issue 7 2010William Art Counts Abstract Ab initio calculations are becoming increasingly important for designing new alloys as these calculations can accurately predict basic structural, mechanical, and functional properties using only the atomic composition as a basis. In this paper, fundamental physical properties (like formation energies and elastic constants) of a set of bcc Mg,Li and Mg,Li-based compounds are calculated using density functional theory (DFT). These DFT-determined properties are in turn used to calculate engineering parameters such as (i) specific Young's modulus (Y/,) or (ii) shear over bulk modulus ratio (G/B) differentiating between brittle and ductile behavior. These parameters are then used to identify those alloys that have optimal mechanical properties for lightweight structural applications. First, in case of the binary Mg,Li system, an Ashby map containing Y/, versus G/B shows that it is not possible to increase Y/, without simultaneously increasing G/B (i.e., brittleness) by changing only the composition of a binary alloy. In an attempt to bypass such a fundamental materials-design limitation, a set of Mg,Li,X ternaries (X,=,Ca, Al, Si, Cu, Zn) based on stoichiometric Mg,Li with CsCl structure was studied. It is shown that none of the studied ternary solutes is able to simultaneously improve both specific Young's modulus and ductility. [source] Determination of the local structure of the first and second shells in ordered and disordered Ni,Mn alloysJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2001A. V. Ryazhkin The coordination numbers and the interatomic distances for 50, 75 and 80 at.% Ni-Mn alloys in ordered and disordered states are presented. A new method for determining the first and second nearest neighbor coordination numbers in a binary alloy is applied. It is shown that magnetic properties of these alloys depend on short range order in atomic arrangement. [source] Effects of Hf content and immersion time on electrochemical behavior of biomedical Ti-22Nb- xHf alloys in 0.9% NaCl solutionMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 5 2009B. L. Wang Abstract The aim of this study was to investigate the effects of Hf content and immersion time on the electrochemical corrosion behavior of the Ti-22Nb- xHf (x,=,0, 2, 4, and 6 at%) alloy samples in 0.9% NaCl solution at 37,°C and neutral pH range, utilizing the potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. From the polarization curves, all these alloys exhibited typical passive behavior, which was indicated by a wide passive region without the breakdown of the passive films and low corrosion current densities. In addition, the values of the corrosion current densities and passive current densities decreased with increase in the Hf content. The EIS results, fitted by RS(QPRP) model, exhibited capacitive behavior (high corrosion resistance) with phase angles closed to ,80° and high impedance values at low and medium frequencies, indicating the formation of a highly stable film on these alloys in the test solution. The resistance of the passive films improved with increase in the Hf content and immersion time. All these observations suggested a more noble electrochemical behavior of the Ti-22Nb- xHf alloys compared to the Ti-Nb binary alloy. [source] Existence of solutions to an anisotropic phase-field modelMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 13 2003Erik Burman Abstract We consider an anisotropic phase-field model for the isothermal solidification of a binary alloy due to Warren,Boettinger ( Acta. Metall. Mater. 1995; 43(2):689). Existence of weak solutions is established under a certain convexity condition on the strongly non-linear second-order anisotropic operator and Lipschitz and boundedness assumptions for the non-linearities. A maximum principle holds that guarantees the existence of a solution under physical assumptions on the non-linearities. The qualitative properties of the solutions are illustrated by a numerical example. Copyright © 2003 John Wiley & Sons, Ltd. [source] Weak solutions of a phase-field model for phase change of an alloy with thermal propertiesMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 14 2002José Luiz Boldrini The phase-field method provides a mathematical description for free-boundary problems associated to physical processes with phase transitions. It postulates the existence of a function, called the phase-field, whose value identifies the phase at a particular point in space and time. The method is particularly suitable for cases with complex growth structures occurring during phase transitions. The mathematical model studied in this work describes the solidification process occurring in a binary alloy with temperature-dependent properties. It is based on a highly non-linear degenerate parabolic system of partial differential equations with three independent variables: phase-field, solute concentration and temperature. Existence of weak solutions for this system is obtained via the introduction of a regularized problem, followed by the derivation of suitable estimates and the application of compactness arguments. Copyright © 2002 John Wiley & Sons, Ltd. [source] Structural study on the crystallization behavior of Sb3Te2 alloy for phase change memoryPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 1 2007Chang Woo Sun Abstract The atomic crystal structure of the Sb3Te2 binary alloy has been investigated with high-resolution transmission electron microscopy (HR-TEM) and fast Fourier transform patterns. As a result, there is inconsistency between the previous theoretical model and the experimental result. But, from the calculations of lattice parameters and the number of layers in the unit cell, it is found that the Sb3Te2 alloy can be crystallized into the Sb2Te structure with Pm1 space group and the difference between stacking sequences of the Sb3Te2 and the Sb2Te structures has been discussed with the proposed atomic arrangement model of unit cells. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Numerical Determination of Heat Distribution and Castability Simulations of as Cast Mg,Al Alloys,ADVANCED ENGINEERING MATERIALS, Issue 3 2009Shehzad Saleem Khan Magnesium alloys offer a large potential as lightweight structures especially in the automotive industry. Research and development of magnesium alloys depend largely on the metallurgist's understanding and ability to control the microstructure of the as cast part. This research work comprises the determination of experimental parameters to simulate fluidity and microstructure of magnesium/aluminum binary alloys. [source] Dendritic solidification of binary alloys with free and forced convectionINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 3 2005P. Zhao Abstract Dendritic solidification with forced convection and free convection driven by contraction and thermo- solutal buoyancy is simulated in two-dimensional space using a sharp-interface model. Both pure substances and alloys are considered. The model is formulated using the finite element method and works directly with primitive variables. The coupled energy- and solutal concentration-equations, along with the Navier,Stokes equations for incompressible flow, are solved using different meshes. Temperature is solved in a fixed mesh that covers the whole domain (solid + liquid) where the solid,liquid interface is explicitly tracked using marker points. The concentration and momentum equations are solved in the liquid region using an adaptive mesh of triangular elements that conforms to the interface. The velocity boundary conditions are applied directly on the interface. The model is validated using a series of problems that have analytical, experimental and numerical results. Four simulations are presented: (1) crystal growth of succinonitrile with thermal convection under two small undercoolings; (2) dendritic growth into an undercooled pure melt with a uniform forced flow; (3) equiaxial dendritic growth of a pure substance and an alloy with contraction-induced convection; and (4) directional solidification of Pb,0.2 wt% Sb alloy with convection driven by the combined action of contraction, thermal and solutal buoyancy. Some of the simulation results are compared to those reported using other methods including the phase-field method; others are new. In each case, the effects of convection on dendritic solidification are analysed. Copyright © 2005 John Wiley & Sons, Ltd. [source] Application of the parametric bootstrap method to determine statistical errors in quantitative X-ray microanalysis of thin filmsJOURNAL OF MICROSCOPY, Issue 1 2007ALDO ARMIGLIATO Summary We applied the parametric bootstrap to the X-ray microanalysis of Si-Ge binary alloys, in order to assess the dependence of the Ge concentrations and the local film thickness, obtained by using previously described Monte Carlo methods, on the precision of the measured intensities. We show how it is possible by this method to determine the statistical errors associated with the quantitative analysis performed in sample regions of different composition and thickness, but by conducting only one measurement. We recommend the use of the bootstrap for a broad range of applications for quantitative microanalysis to estimate the precision of the final results and to compare the performances of different methods to each other. Finally, we exploited a test based on bootstrap confidence intervals to ascertain if, for given X-ray intensities, different values of the estimated composition in two points of the sample are indicative of an actual lack of homogeneity. [source] PALS investigation of chromium effect in ferritic/martensitic steels implanted with heliumPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2009Stanislav Sojak Abstract Chromium is an element with significant effect on the elevated temperature corrosion resistance and the low radiation induced void swelling. There were several studies carried out with regard to effect of Cr on the defect creation and stability [1, 2], but this issue is not fully understood yet. This paper contributes to this research with the study of Fe-Cr binary alloys with different Cr content, implanted by helium by the use of cascade accelerator and investigated by conventional PALS set-up. Our measurements show that chromium plays a role in the formation of small vacancy clusters, affecting the size and distribution of these defects. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Formation of binary alloy cluster ions from group-14 elements and cobalt and comparison with solid-state alloysRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 24 2001Xia Zhang By using laser ablation on mixtures of transition metal cobalt and group-14 elements, binary alloy cluster anions were produced while no binary alloy cluster cations were detected, and the homocluster cations of group-14 elements appeared at very low abundance. The differences between clustering abilities of germanium, tin and lead with cobalt are described, and the chemical bonds in the binary alloy cluster anions appear to indicate a transition from covalent to metal bonds. The cluster anion [CoPb10], appears in very high abundance (magic number), and an endohedral structure is proposed for this cluster. The cluster anion [CoPb12],, also representing a magic number, probably has an icosahedral structure. Compared with solid-state Co/Ge binary alloys, the compositions of most binary alloy cluster anions are germanium-rich, in which the covalent bonds are predominant. Copyright © 2001 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||