Showing papers on "Ternary operation published in 1994"

Summary of constitutional data on the Aluminum-Carbon-Titanium system

Abstract: The constitution of the titanium-aluminum-carbon ternary system has been investigated combining critical evaluation of literature data with new experimental results. Three ternary phases occur in this system: Ti3AlC, Ti2AlC, and newly discovered Ti3AlC2. As analyzed by wet chemistry methods, all three phases are carbon deficient with respect to their “ideal≓ stoichiometry, which is based on the crystal structure formula. Ti2AlC and Ti3AlC melt incongruently at 1625 ± 10 ‡ and 1580 ± 10 ‡, respectively. Ti3AlC2 decomposes in the solid state. The two isothermal sections at 1000 and 1300 ‡ investigated experimentally are corroborated by thermochemical calculations. A projection of the liquidus surface is given, and a reaction scheme linking this liquidus projection with the isothermal sections observed is proposed.

Handbook of Crystal Structures and Magnetic Properties of Rare Earth Intermetallics

Abstract: Introduction. Crystal Structures of Ternary Lanthanide Intermetallics. Magnetic Properties of Intermetallics. Magnetic Properties of the Intermetallic RxTyXz Compounds with y/xGBP2. Magnetic Materials Based on 3D-Rich Ternary Compounds. Concluding Remarks.

Self-consistent interatomic potentials for the simulation of binary and ternary oxides

Abstract: A consistent set of pair potentials has been derived empirically by fitting to the experimentally measured lattice properties of a series of binary metal oxides. In contrast to previous strategies, the potential parameters required to reproduce the experimental lattice properties of all the chosen compounds were optimised concurrently, utilising residuals from all structures in the series, each calculated from the energy-minimised geometry. A more reliable determination of ion polarisabilities can thus be made.

On the Sn-Bi-Ag ternary phase diagram

Abstract: The selection and evaluation of Pb-free solders requires information that is best determined through a knowledge of ternary and higher order phase diagrams. As part of an ongoing program on Pb-free solder phase diagrams at the National Institute of Standards and Technology, a thermodynamic model is formulated for the Sn-Bi-Ag phase diagram. Thermodynamic functions for the various phases obtained by fitting measured data for the three constituent binary systems are extrapolated to the ternary system using the method of Muggianu. Modeling results are compared to preliminary experimental data for the ternary system and are applied in the calculation of the solidification path.

Amorphous (Ti,Zr, Hf)NiCu ternary alloys with a wide supercooled liquid region

Abstract: Ternary TiNiCu, ZrNiCu and HfNiCu amorphous alloys were found to exhibit a distinct glass transition combined with rather wide supercooled liquid region before crystallization. The largest temperature interval of the supercooled liquid region defined by the difference between TgTx, i.e. ΔTx (= Tx−Tg, is 55 K for Ti50Ni25Cu25, 60 K for Zr60Ni20Cu20 and 65 K for Hf60Ni20Cu20. These amorphous alloys with the largest ΔTx values also exhibit the highest Tx and the lowest melting temperature and crystallize through asingle-stage exothermic reaction leading to the simultaneous precipitation of more than two kinds of compound. It is therefore presumed that the appearance of the wide supercooled liquid region before crsystallization is due mainly to the necessary of the redistribution of the constituent elements for the precipitation of the compounds from the homogeneously mixed amorphous structure.

Solubilities of carbon dioxide in water + monoethanolamine + 2-amino-2-methyl-1-propanol

Abstract: The solubilities of carbon dioxide in water (1) + monoethanolamine (2) + 2-amino-2-methyl-1-propanol (3) have been measured at 40, 60, 80, and 100 C and at partial pressures of carbon dioxide ranging from 1.0 to 200 kPa. The ternary mixtures studied were w[sub 2] = 0, w[sub 3] = 0.3; w[sub 2] = 0.06, w[sub 3] = 0.24; w[sub 2] = 0.12, w[sub 3] = 0.18; w[sub 2] = 0.18, w[sub 3] = 0.12; and w[sub 2] = 0.24, w[sub 3] = 0.06 where w is the mass fraction. The modified Kent and Eisenberg model has been used to represent the solubility of CO[sub 2] in the ternary solutions. The model reasonably reproduces the equilibrium partial pressure of CO[sub 2] above the ternary solutions, not only over a temperature range from 40 to 100 C, but also for various concentrations of components in the ternary solutions.

synergistic Coordination in Ternary Complexes of Eu3+ with Aromatic .beta.-Diketone Ligands and 1,10-Phenanthroline

Abstract: Luminescence spectroscopy was used to probe the molecular and electronic structure of ternary europium (III) complexes with 1,10-phenanthroline and aromatic {beta}-diketone ligands in aqueous solution. These complexes are unique in that either type of ligand binds only weakly or not at all when presented to the Eu(III) alone. Certain ligand combinations did not form complexes. Stoichiometry and electronic transitions for these complexes is reported.

Thermodynamics of phase equilibria in aqueous-organic systems with salt

Abstract: A semiempirical thermodynamic method is developed to establish a framework for calculating vapor-liquid and liquid-liquid equilibria in ternary systems containing water, an organic solvent, and a salt. Careful attention is given to precise definition of standard states. Short-range ion-solvent forces are taken into account primarily by a chemical-equilibrium method based on stepwise ion solvation; however, physical contributions also contribute. Water-cosolvent nonideality is described by an extended equation of the van Laar form. Long-range electrostatic forces between ions are taken into account by an extended Debye-Huckel equation with corrections for transferring from a McMillan-Mayer to a Lewis-Randall framework. The new method is illustrated with results for several systems including saturated aqueous mixtures of LiBr or LiCl with methanol where the salt concentration exceeds 20 molal. The method developed here is of particular interest for process calculations in extractive crystallization, a low-energy operation for producing salt from aqueous solution.

A thermodynamic study of the phase equilibria in the Bi-Sn-Sb system

Abstract: A thermodynamic study has been carried out on the Bi-Sn-Sb ternary alloy system. The Gibbs energy of individual phases has been approximated using the regular solution, two-sublattice model, and the thermodynamic parameters for each phase have been evaluated using the available experimental information on phase boundaries and other related thermodynamic properties. Thermal analysis experiments have also been performed on several ternary alloys to re-examine and augment the available ternary experimental data. The set of evaluated thermodynamic parameters arrived at in this study, enables reproducible calculations of the liquidus and solidus temperatures and vertical section diagrams quite satisfactorily.

Calculating critical transitions of fluid mixtures: Theory vs. experiment

Abstract: The progress in predicting critical transitions in fluid mixtures is reviewed. The critical state provides a valuable insight into the general phase behavior of a fluid and is closely linked with the nature and strength of intermolecular interaction. Calculations of critical equilibria have been confined mainly to binary mixtures. The prediction of binary gas-liquid critical properties was initially limited to empirical correlations. These techniques have been superseded by rigorous calculations of the critical conditions using realistic models of the fluid or equations of state. All of the known types of critical phenomena exhibited by binary mixtures can be, at least, qualitatively calculated. If an optimal combining rule parameter is allowed, continuous gas-liquid properties can be calculated accurately for a wide variety of mixtures. Similarly, the pressure and composition dependence of upper critical solution phenomena can be accurately predicted. Progress has been achieved in predicting discontinuous critical transitions in polar and nonpolar binary mixtures. There is increasing interest in calculating the critical properties of ternary and multicomponent mixtures. Although the techniques applied to binary mixtures often can be directly extended to ternary mixture calculations, calculated critical properties of ternary mixtures indicate that their behavior cannot be considered as a simple extension of binary mixture phenomena. Consequently, ternary critical calculations are likely to provide a superior insight into the phase behavior of multicomponent fluids.

Computer simulation of spinodal decomposition in ternary systems

Abstract: The non-linear spinodal decomposition kinetics of a quenched homogeneous ternary alloy within three- or two-phase fields is modeled using a computer simulation technique formulated in the reciprocal lattice. Based on two-dimensional computer simulations, it is shown that, similar to binary alloys, spinodal decomposition in a ternary system usually produces interconnected morphologies at the very early stages of decomposition. For most of the compositions investigated, a decomposition of a homogeneous phase into three phases takes place in two stages. For some compositions, the two stages are the phase separation of an homogeneous phase into two phases, followed by further phase separation of one of the two phases into another two phases, resulting in a three-phase mixture. For other compositions, the first stage is a phase separation of an initially homogeneous phase into a two-phase mixture followed by a second stage, the appearance of a third phase along the existing interphase boundaries. This sequential phase separation in a ternary alloy can be justified from a thermodynamic stability analysis combined with the knowledge of the thermodynamic driving force for phase separation. It is also demonstrated that a third minor component strongly segregates to interphase boundaries during spinodal decomposition and subsequent coarsening of a homogeneous ternary alloy into two phases.

Precipitation hardening in ternary alloys of the AlScCu and AlScSi systems

Abstract: The processes of precipitation hardening in cast ternary alloys of the AlScCu and AlScSi systems were studied in the temperature range of aging from 100 to 450°C and at exposures to 200 h It was shown that the CuAl2 and ScAl3 phases were involved in the process of aging in ternary AlScCu alloys, and the Si and V (AlSiSc) phases, in ternary AlScSi alloys with excess silicon in a supersaturated solid solution The V phase was for the first time revealed as the hardening phase in aluminum alloys

Stabilized microporous materials

Abstract: The invention involves a polymeric, microporous membrane material characterized by a continuous-triply-periodic, highly branched and interconnected pore space morphology having a globally uniform, pre-selected pore size, characterized by high porosity. And further involves several related methods for forming mircorporous membrane materials; including polymerization of the hydrophobic component in a ternary surfactant/water/hydrophobe cubic phase, and other thermodynamically stable or metastable phases of phase-segregated systems, especially systems which are substantially ternary or binary, and particualarly directed to applications of the novel material in: immobilization, encapsulation, and/or controlled release of biologically active agents, and other applications where a controlled pore size is necessary or advantageous.

Structure of Polyelectrolyte Stars and Convex Polyelectrolyte Brushes

Abstract: The structure of polyelectrolyte stars and spherical brushes is discussed using a local force balance argument that balances the osmotic pressure and the tension in the chains locally for a given radial position. In general, there are four distinct regions where the segment density profile Φ(r) is dominated by one of the interactions: (i) in the outer region, electrostatic interactions dominate, (ii) in the intermediate region, binary interactions dominate, (iii) in the inner region ternary interactions dominate, and finally (iv) at the center of the star (of the order of a few segment lengths), the density is unity. For poor solvents we predict a collapse induced by the attractive binary interactions that leads to a two-phase star or brush

An improved model for mass transfer during the formation of polymeric membranes by the immersion-precipitation process

Abstract: An analysis is presented, which describes the isothermal ternary diffusion process encountered in the formation of a cellulose acetate polymeric membrane by a direct immersion-precipitation of polymeric solutions in a nonsolvent bath. A material coordinate was employed to derive the mass transfer equations for the membrane solution and the convective mass transfer in the coagulation bath was taken into account by solving the hydrodynamic boundary layer equations. Diffusion coefficients were measured and used to deduce ternary phenomenological coefficients. The computed results are found to agree with the experimental precipitation time and membrane morphologies observed in scanning electron photomicrographs. © 1994 John Wiley & Sons, Inc.

Critical evaluation and optimization of the thermodynamic properties and phase diagrams of the Al-Mg, Al-Sr, Mg-Sr, and Al-Mg-Sr systems

Abstract: All available thermodynamic and phase diagram data were critically assessed for all phases in the Al-Mg, Al-Sr, and Mg-Sr systems at 1 bar pressure from room temperature to above the liquidus temperatures. For these systems, all reliable data were simultaneously optimized to obtain a set of model equations for the Gibbs energy of the liquid alloy and all solid phases as functions of composition and temperature. The modified quasi-chemical model was used for the liquid. The Al-Mg-Sr ternary phase diagram was calculated from the optimized thermodynamic properties of the binary systems. Since no reliable ternary data were available, three assumptions were made: no ternary terms were added to the model parameters for the thermodynamic properties of the liquid, no ternary solid solutions are present in the system, and no ternary compound is present in the system. The calculated ternary phase diagram is thus a first approximation, which can be improved by the addition of new experimental data and can be used as a base for the calculation of phase diagrams of multicomponent systems.

New routes to alkali-metal–rare-earth-metal sulfides

Abstract: Ternary alkali-metal–rare-earth-metal sulfides, MRES2(M = Li, Na, K; RE = Y, La–Yb) were prepared by heating RECL3and M2S under an H2S–N2 atmosphere at 750–800 °C for 10 min. The ternary sulfides form thin, mostly coloured plates. The structures were characterised by X-ray powder diffraction, which revealed high-temperature cubic modifications for LiHoS2 and LiErS2. The disordered cubic form (NaCl type) was observed for LiLnS2(Ln = Pr–Er) and NaLnS2(Ln = La–Nd), while the ordered rhombohedral form (α-NaFeO2 type) was observed for LiYbS2, NaLnS2(Sm–Yb) and KLnS2(La–Yb). Alkali-metal–rare-earth-metal sulfides may also be synthesized from the rare-earth-metal chloride and alkali-metal halide under comparable conditions. Similarly, thermolysis of the rare-earth-metal sesquisulfide (γ-RE2S3), oxysulfide (RE2O2S) or oxychloride (REOCL) with M2S or MCI in an atmosphere of H2S-N2 gives MRES2. The materials were characterised by powder X-ray diffraction, scanning electron microscopy (SEM), energy dispersive analysis by X-rays (EDXA), Raman, infrared, magnetic moments and microanalysis.

Contribution to the experimental and thermodynamic assessment of the AlCaFeSi system—I. AlCaFe, AlCaSi, AlFeSi and CaFeSi systems

Abstract: The binary Al-Ca, Ca-Fe, Ca-Si systems and the ternary Al-Ca-Fe, Al -Fe-Si, Ca-Fe-Si systems were thermodynamically assessed. Experimental determination of the enthalpy of fusion of the ternary compounds Si2Al2Ca, Si7Al8Fe5 and Si2Al3Fe, as well as invariant temperatures in the Al-Ca-Si and Al-Fe-Si systems were derived from DTA measurements. A set of thermodynamic parameters consistent with the phase diagram, mainly in the Si-rich region, is obtained.

Ground states of a ternary fcc lattice model with nearest- and next-nearest-neighbor interactions.

Abstract: The possible ground states of a ternary fcc lattice model with nearest- and next-nearest-neighbor pair interactions are investigated by constructing an eight-dimensional configuration polytope and enumerating its vertices. Although a structure could not be constructed for most of the vertices, 31 ternary ground states are found, some of which correspond to structures that have been observed experimentally.