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The AlO 1.5 -YO 1.5 system has been assessed using the CALPHAD technique. The liquid phase was described by a subregular substitutional solution model. All solid phases were treated as stoichiometric compounds. A consistent set of parameters describing the Gibbs energy of the phases was obtained by a computerized least squares method. Stable and metastable phase...
A technique has been developed for the calculation of chemical equilibrium of a closed multicomponent heterogeneous system for the given values of temperature, pressure and feed composition. The method is based on the consecutive exclusion and inclusion of the phases from and into the calculation process till the system is thermodynamically stable with respect to the phases not included in the system...
The available experimental information is not sufficient to determine the temperature dependence of excess Gibbs energy of the liquid Cu-Cr alloys. The previously optimized excess entropy of mixing of the liquid phase is too positive. A new set of optimized thermodynamic functions of the Cu-Cr system has been obtained from thermodynamic and phase diagram data incorporating the latest data. The Tanaka-Gokcen-Morita...
The system laevorotatory-carvoxime + dextrorotatory-carvoxime displays unique thermodynamical and structural properties. Its solid-liquid phase diagram, having a maximum, suggests a continuous series of mixed crystals of the disordered substitutional type. The maximum, however, corresponds to an ordered structure. On the basis of phase diagram and thermochemical data a macroscopic thermodynamic...
Critically selected experimental data from the literature and estimated values are employed for the assessment of the Gibbs energies of all phases in the system Ba-O. The standard element reference state, SER, has been used throughout. For the gas phase the species Ba G , Ba G2 , BaO G , Ba 2 O G2 , Ba 2 O G , O G , O ...
Available experimental information concerning thermodynamic properties as well as phase equilibria has been compiled and used for the assessment of new self-consistent parameters for all phases in the Mn-Si system, by means of the well-known Lukas et al. 's program. Phase diagram and characteristic thermodynamic functions have been calculated and compared with the experimental values, leading to...
The Discrete Complex Anion Model was introduced to the molten salt systems of LiF-MgF 2 , NaF-MgF 2 , and KF-MgF 2 , based upon the assumption of existence of the MgF -3 complex ions contained in the melts. A set of parameters were evaluated from the experimental data representing the enthalpies of mixing and the phase diagrams of all these three systems. The...
By examining the relationship between grand potential and various distribution variables, this paper combines the Natural Iteration Method (NIM) with the Step Speeded Method and Dichotomous method, respectively, and proposes two methods, Step Speeded- and Dichotomous-NIMs, for improving the conventional NIM by making use of the absolute convergence of the NIM. The calculated results indicate the numbers...
A thermodynamic analysis is presented for three binary systems out of the four neopentane derivatives: neopentylglycol (NPG), pentaglycerin (PG), pentaerythritol (PE) and tris(hydroxymethyl)aminomethane (TRIS). These substances give rise to a plastic crystalline state, which is bcc for TRIS and fcc for NPG, PG and PE. In each of the three systems considered TRIS is one of the components: they are...
A critical assessment of the Fe-Sb system was carried out by using a computerized technique. Both the liquid and solid solution phases were described by regular solution models. Nonstoichiometric phase, -FeSb, was modeled as (Fe)(Fe,Sb), and FeSb 2 was treated as a stoichiometric compound. A set of parameters describing the Gibbs energies of the different phases was optimized by using...
The Embedded Atom Method (EAM) was combined with the quasiharmonic approximation to determine the enthalpies and the free energies of mixing for a number of binary f.c.c. and b.c.c. metallic solid solutions. In each case, the EAM potential functions were determined using only the data for the constituent elements. It was found that when two f.c.c. elements are mixed to form an f.c.c. solid solution,...
Experimental investigations of the thermochemical properties of the phases in the system Ba-Cu-O by means of DTA and calorimetric measurements are reported. The results together with critically selected data from the literature are used for an assessment of the Gibbs energies of the ternary phases (based on the Standard Element Reference State, SER). For the binary subsystems critically assessed...
An algorithm for the systematic investigation of the values of the excess Gibbs free energy of a ternary system and the partial excess Gibbs free energies of its components as predicted by a large class of three-factor models in the subregular approximation is presented. The equations used in ternary phase diagram calculation are written in a form that emphasizes the three-factor model dependent...
A thermodynamic study of the Zr-B-H-Cl system was made at low temperature (800 to 1500K) and low pressure (1 to 100 mbar) by minimising of the total Gibbs free energy of the system. The Zr-B phase-diagrams showed that ZrB 2 is the main solid product formed. The ZrB 2 yield can reach 100% under conditions of elevated temperature, high H 2 concentrations, and at low pressures...
The species chemical potential/bond energy model provides a basis for understanding the thermodynamic properties of phases that may be considered to consist of multiple sublattices. In this paper the model is applied to compound semiconductors, with a simple model for GaAs being used for illustration purposes.
An optimization routine has been incorporated into ChemSage, a software package for Gibbs-energy minimization calculations. Standard Gibbs energies, excess Gibbs functions, and molar volume data can be optimized with regard to several types of experimental information, e.g., phase equilibria, activities, calorimetric, potentiometric, and density data. Parameters for all available solution models...
The development of principles that might ease writing software for thermodynamic calculations with any participating solutions has been considered as the objective of this paper. To this end, the object-oriented programming is suggested to apply, which, in fact, allows the creation of a new specialised algorithmic language, rather universal and flexible, for programming of sophisticated thermodynamic...
Unusual age hardening of Al-Cu-Mg-Ag alloys with high Cu:Mg ratios has been found to be associated with the formation of the Ω phase. A thermodynamic modelling approach is adopted in the present study to investigate the likelihood of Ag-Mg intermetallic compounds which have been proposed as the initial nuclei for the Ω precipitates. The Thermo-Calc computer package has been used for the present...
Equations presented previously for the Species Chemical Potential Bond Energy model for two sublattices are developed in order to permit its application to any number of sublattices.
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