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Thermodynamic parameters for minerals in the FeO-MgO-Al 2 O 3 -SiO 2 (FMAS) system have been assessed from phase equilibria at pressures up to 30 GPa. All solid solution phases except orthopyroxene have been described by the sublattice model. Calculated phase diagrams of end member systems, exchange reactions in the FMAS system, phase equilibria for fixed compositions at pressures...
Results of thermodynamic predicting methods applied to Ga-Sb-Bi system are presented in this paper. Chou, Toop and Hillert model were used for the calculation and comparison of the characteristic thermodynamic quantities in five selected sections of the ternary system Ga-Sb-Bi at a temperature of 1073K.
The CaO-B 2 O 3 pseudo-binary system has been assessed thermodynamically. A two-sublattice ionic solution model, (Ca +2 ) P (O -2 ,BO 3-3 ,B 4 O 7-2 , B 3 O 4.5 ) Q was adopted to describe the liquid phase. All the solid phases are treated as stoichiometric compounds. ...
A series of Fe-Al alloys with various contents of aluminium (from 1 to 10 weight percent) was investigated by X-ray diffraction. The unit cell parameters and molar volumes of these alloys were measured at ambient conditions. The thermal expansions of two alloys (with 5 and 10 weight % Al) were obtained in the temperature range of 293-1370 K. The specimen was heated by passing an electrical current...
The validity of the regular associated solution (RAS) model for describing the thermodynamic properties of complex liquid alloys has been analysed by applying it to the Cu-In system. The presence of Cu 3 In as the associated species in equilibrium with the free atoms in the liquid state was assumed. Liquid copper-indium alloys exhibit a very complex thermodynamic behaviour where the deviations...
Thermodynamic optimization of systems Cr-P and Fe-Cr-P has been made by using classical thermodynamic models for describing the properties of the individual phases of the systems. The thermodynamic parameters of sub-systems Fe-Cr and Fe-P for Fe-Cr-P were taken from earlier assessments and the parameters of systems Cr-P and Fe-Cr-P were optimized by using recently measured activity and Gibbs energy...
In order to optimize the binary Ge-Te system available experimental data were critically compiled from the literature. The cubic high-temperature β-phase and the rhomboedric room-temperature α-phase were described by a two-sublattice model with one kind of defect (vacancies on germanium sites). The room-temperature orthorhombic γ-phase was treated as a stoichiometric compound, as there is a lack...
A new version of the software package IVTANTHERMO for Windows intended for thermodynamic modelling of complex chemically reacting systems is described. The package includes an extensive database on thermodynamic properties of individual aubstances database handling and a program, which allows the calculation of equilibrium composition and thermodynamic properties of the system to be eqamined. The...
At high SiO 2 contents, a model of Na 2 O-K 2 O-Al 2 O 3 -SiO 2 melts must take into account the ''large compensation effect'' whereby the replacement of a tetravalent Si 4+ by a trivalent A1 3+ in the silicate network is facilitated by the formation of (NaAl) 4+ or (KAl) 4+ associates. This effect...
Thermodynamic reoptimization has been made for the Fe-Cr-Ni system with emphasis on the iron-rich corner of the system. New ternary substitutional-solution interaction parameters were optimized for the liquid, fcc and bcc phases and a new Gibbs energy expression was suggested for one hypothetical component of the sigma phase. The rest of the data concerning the binary subsystems and the sigma phase...
Theoritical formulae prve been derived for determining the activity along a three-phase boundary in a three component system. The activities can be calculated from ternary phase diagrams from the partial thermodynamic properties and the use of a single integration constant. The latter is calculated from the binary phase diagrams. The formulae are rigorous and no assumption is made.
Although two (or effectively two) sublattice modelling of ordered phases has been the norm in carrying out phase diagram assessments, it is argued that this kind of modelling should, in general, be discouraged for these phases. Two-sublattice modelling gives a Gibbs energy minimum (with reference states at the same temperature and with the same parent structure as the ordered phase) for every ordered...
A thermodynamic optimization has been made for the solution phases of the ternary systems Fe-Cr-Si and Fe-Ni-Si in the iron-rich corner. Ternary substitutional-solution interaction parameters were optimized for the liquid, fcc and bcc phases, and the lower-order data were taken from the earlier assessed sub-systems. The calculated results were validated with experiments of phase equilibri and component...
The complete titanium-oxygen system from metallic titanium to gaseous oxygen including Magneli phases was critically assessed between 298 K and liquidus temperatures and at a pressure of 1 bar. All available experimental T-x phase diagram and thermodynamic data - all in all about 600 data points - were applied to model the Gibbs energies of totally eighteen phases. Of these, twelve were treated...
Based on thermodynamic and phase diagram data, the Gibbs energies of mixing of the solution phases in the Pu-U and Pu-Zr systems were calculated using an optimization procedure. The use of thermodynamic data in the optimization made it possible to accurately calculate thermodynamic properties as well as the phase diagrams, which were in good agreement with the respective experimental values. The...
The phase equilibria and thermodynamic properties of the binary Co-Ta system were analyzed and a complete thermodynamic description of the binary system was obtained with the CALPHAD technique using a computerized optimization procedure. The thermodynamic descriptions of pure Co and Ta elements were taken from the SGTE database. Based on the experimental data, six binary intermetallic compounds...
The knowledge of the non-metallic phases in equilibrium with liquid steel is very important to the design and control of the results of steelmaking operations, in particular deoxidation, desulfurization and inclusion shape control. Thus, through the control of steel and slag composition it is possible, for instance, to tailor non-metallic inclusions to achieve maximum deformability, to avoid nozzle...
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