A thermodynamic evaluation of the FeMoC system

A new evaluation of the Fe-Mo-C system has been made using a sublattice model and including the magnetic effect. A set of parameter values describing the Gibbs energy of each individual phase was determined with a computerized optimization technique. It gives satisfactory agreement with the experimental information over a wide temperature range. Several diagrams and tables concerning phase equilibria are presented.     

Thermodynamic properties of MoC

An evaluation of the Mo-C system has been made using a sublattice model. A set of parameter values describing the Gibbs energy of each individual phase was determined with a computerized optimization technique. It gives satisfactory agreement with the experimental information over a wide temperature range. Several diagrams and tables concerning phase equilibria are presented.     

Calculation of thermodynamic properties of LiFAlF3, NaFAlF3 and KFAlF3

The scheme of dissociation of cryolite in NaFAlF₃ melts is proposed and applied to the LiFAlF₃ and KFAlF₃ systems. The constants and enthalpies of dissociation for alkali-cryolites are evaluated from experimental data. The mole fractions of each proposed species at 1298K in these three melt systems are calculated, and the variation of alumina solubility in alkali-cryolite can be explained on the basis of the ionic structure for the MF- AlF₃ (M: Li, Na and K) melts. The thermodynamic properties and liquidus data of MF-AlF₃ systems are calculated by using the selected evaluated parameters. Some results are compared with experimental values.     

Calculation of the FeZnSi phase diagram between 773 and 1173 K

The phase diagram for the Fe-Zn-Si system has been calculated from thermodynamic data for the binary systems. The excess Gibbs energies of the solid and liquid solutions in the ternary system are described by: ΔG^xs = ΔG^xs₁₂ + ΔG^xs₁₃ + ΔG^xs₂₃ + ΔG^xs₁₂₃ with: ΔG^xs_ij = x_ix_j(A_ijx_i + B_ijx_j)ΔG^xs₁₂₃ = A₁₂₃x₁x₂x₃ The ternary interaction parameter A₁₂₃ is obtained from experimental characteristics of the ternary diagram: temperature dependance on the solubility of Zn in Fe₃Si and FeSi in Zn. The diagram Fe-Zn-Si calculated between 773 and 1173 K is used for explaining diffusion path observed during galvanization of the Fe-Si alloys.     

Thermodynamic study of the KMgAlClSO4H2O system at the temperature 298.15 K

The Pitzer ion-interaction model has been used for thermodynamic simulation of the binary AlCl₃H₂O, Al₂(SO4)₃H2O, ternary KClAlCl₃H₂O, K₂SO₄Al₂(SO₄)₃H₂O, MgCl₂AlCl₃H₂O, MgSO₄Al₂(SO₄)₃H₂O, and the quaternary KClMgCl₂AlCl₃H₂O systems at T=298.15 K. The optimum values of the binary parameters of ionic interactions for aluminum solutions have been calculated using activity data up to saturation of solutions. The ternary parameters have been chosen on the basis of the compositions of saturated ternary solutions taking into account the unsymmetrical mixing terms. Good agreement between experimentally determined and calculated solubilities has been found. Important thermodynamic characteristics (thermodynamic solubility product, standard molar Gibbs energy of formation) of the solid phases (simple and double salts) crystallizing in the systems under consideration are determined.     

Application of the Hoch-Arpshofen model to the SiO2CaOMgOAl2O3 system

The Hoch-Arpshofen model was applied to the SiO₂-CaO-MgO-Al₂O₃ system. First the binary interaction coefficients, obtained from the six binary systems, were used to calculate the Gibbs energy of formation of the ternary compounds present in the four ternary systems; then the calculated activities of SiO₂, CaO, and Al₂O₃ were compared with the measured activities. The calculated Gibbs energies of formation of anorthite, gehlenite, and cordierite agree with the measured energies; the measured enthalpies of formation of akermanite, diopside, merwinite, and monticellite must be multiplied by 0.568 ± 0.031 to obtain agreement. The Gibbs energy of formation of 3CaO-MgO-2Al₂O₃ was also calculated. The calculated activity data agree with some authors' measurements and not with others.     

CALPHAD: Phase diagram of the system KFK2MoO4SiO2

The phase diagrams of the binary systems KFK₂MoO₄, KFSiO₂, and K₂MoO₄SiO₂, as well as that of the ternary system KFK₂MoO₄SiO₂ in the range up to 50 mole % SiO₂, were measured using the thermal analysis method. The thermodynamically consistent phase diagrams were calculated using the coupled analysis of the thermodynamic and phase diagram data.In the system KFK₂MoO₄ the intermediate compound K₃FMoO₄, melting congruently at 751 °C, is formed. This compound divides this system into two simple eutectic ones. The coordinates of the individual eutectic points are: E₁: 30.5 mole % K₂MoO₄, 720.4 °C, and E₂: 58.8 mole % K₂MoO₄, 744.9 °C. In the binary system KFSiO₂ the liquidus curve of KF shows an inflex point, characteristic for reciprocal systems with chemical reaction taking place between components. Similar course of the liquidus curve of K₂MoO₄ was found in the binary system K₂MoO₄SiO₂, indicating the presence of the chemical reaction between components as well. The strong positive deviation from ideal behavior of the ternary system KFK₂MoO₄SiO₂ was ascribed to the possible formation of heteropolyanions [SiMo₁₂O₄₀]⁴⁻ in the melt.In the investigated concentration range of the ternary system no eutectic point has been found. It lies most probably beyond the investigated part of the system. The standard deviation of approximation of the calculated ternary phase diagram is ± 5.9 °C, which is approximately on the same level of magnitude as the estimated experimental error of ± 4 °C.     

A Thermodynamic description and phase relationships of the FeCr system: Part II the liquid phase and the fcc phase

The high-temperature thermodynamic data and phase equilibria of the FeCr binary reported in the literature are assessed. A set of thermodynamic values for the liquid, bcc and fcc phases are obtained. These values are internally consistent and the calculated phase equilibria are in agreement with the measured phase boundary data. Metastable equilibria for the liquid and fcc phases are also calculated.     

A thermodynamic description and phase relationships of the FeCr system: Part I the BCC phase and the sigma phase

A generalized approach which was applied successfully to account for the magnetic contribution to the thermodynamic properties of FeNi is applied to FeCr. The predicted magnetic specific heats for two bcc alloys at x_Cr = 0.16 and 0.21 are in good agreement with the experimental data available in the literature. The magnetic Gihbs energy, enthalpy and entropy for the bcc phase are obtained accordingly. The nonmagnetic thermodynamic properties of the bcc phase are obtained primarily from thermochemical data as well as those for the sigma phase. The calculated stable and metastable equilibria involving the bcc and sigma phases are in reasonable agreement with data reported in the literature. The calculated metastable miscibility gap of the bcc phase is highly asymmetric and the calculated spinodals show unusual features.     

Gibbs energies of formation of Mn3C,M(Fe,Mn)3C and Mn23C6 from the ternary phase equilibria in the FeMnC system

The high temperature phase relations in the FeMnC system have been analyzed in light of the recently developed thermodynamic method by the authors to obtain the Gibbs energies of formation of Mn₂₃C₆ and Mn,C. A new thermodyn/amic treatment is outlined and applied to obtain the stability of the ternary carbide M(Fe,Mn)₃C without any a priori assumption of a solution model for the M₃C phase. The recommended Gibbs energies of formation for the Mn carbides, Mn₃C and Mn₂₃C₆ With γ-Mn (graphite) as the Standard states are:

The present method can be extended to obtain a consistent set of thermodynamic data for binary and ternary carbides from various ternary metal-metal-carbon phase relations.     

Thermodynamic modeling of the ZrO system

In this study, the complete zirconium-oxygen system has been critically assessed at 1 at. from 300°C to liquidus temperatures. Thermochemical measurements and phase diagram data were used to model the Gibbs free energies of seven phases. Additionally, the ordered interstitial HCP-based solutions were included and considered as simple line compounds. By using the PARROT module in Thermo-Calc, it was possible to optimize the parameters of the models used to describe the Gibbs free energies of the HCP, BCC, Liquid, γ ZrO_2−x,β ZrO_2−x and α ZrO_2−x phases. The Gas phase was considered to behave ideally. Although phase diagrams including the stoichiometric zirconia phases have been assessed, this is the first time, to the best of our knowledge that a complete assessment of this system is published.     

CCD:An Integrated C Coding and Debugging Tool

CCD is an integrated software tool which is intended to support the coding and debugging for C language It integrates a hybrid editor,an incremental semantic analyzer,a multi-entry parser,an incremental unparser and a source-level debugger into a single tool.The integration is realized by sharing common knowledge among all the components of the system and by task-oriented conbination of the components,Nonlocal attribute grammar is adopted for specifying the common knowledge about the syntax and semantics of C language.The incremental attribute evaluation is used to implement the semantic analyzer and the unparser to increase system efficiency.CCD keeps the preprocessors and comments most regular to make it practical.     

Locking and shear scaling factors in C° bending elements

Two types of locking are identified in linear field C° elements: locking caused by shear resistance in constant curvature deformation and in linear curvature deformation, respectively. Locking of the first type can be ameliorated by decoupling constant curvature bending from shear, which in some elements can be achieved by selective reduced integration. Once the modes are decoupled, a scaling factor on the shear stiffness can be used to alleviate the second type of locking. These findings are explained in terms of a linear displacement, linear rotation beam element and applied to the improvement of a triangular plate element. It is shown that the resulting triangular plate element is free from locking and performs excellently in a wide variety of problems.     

C2C随想录

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C2C搅局

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