Gibbs Energy Of Liquid Phase Research Articles

Critical Evaluation and Thermodynamic Optimization of the Fe-P System

Thermodynamic optimization of the Fe-P system was performed using the CALculation of PHAse Diagrams (CALPHAD) method based on critical evaluation of all available phase equilibria and thermodynamic data. The Gibbs energies of liquid phase and solid solutions were described using the Modified Quasichemical Model and Compound Energy Formalism, respectively. The Fe-P phase diagram, thermodynamic properties of P in liquid Fe and stability of intermediate iron phosphides (Fe3P, Fe2P, FeP and FeP2) in the entire composition range were reoptimized for resolving the discrepancies left in the previously optimized database. Several problems in previous assessments were resolved, and a more accurate and consistent description of the Fe-P system was achieved compared to experimental data. The distribution of P between molten Fe-P alloys and slag at different temperatures was also calculated to present the applicability of the present work to steel dephosphorization calculation.

Critical Evaluation and Optimization of the Fe-N, Mn-N and Fe-Mn-N Systems

Thermodynamic optimization of the Fe-Mn-N system was performed using CALculation of PHADiagram method based on critical evaluation of all available phase diagrams and thermodynamic data. The Gibbs energies of liquid phase and solid solutions were described using the Modified Quasichemical Model and Compound Energy Formalism, respectively. The Gibbs energies of pure monoatomic N in both liquid and various solid states were newly reassessed for resolving the discrepancies left in the currently available database. Several existing problems in the previous assessments for the binary Fe-N and Mn-N systems were resolved and more precise and consistent description of the ternary Fe-Mn-N system was achieved with less number of model parameters, comparing to the previous assessment.

Thermodynamic Evaluation of NaF-MF n (M=Be, U, Th) Systems for Molten Salt Reactor

The phase diagrams of NaF-BeF2, NaF-ThF4 and NaF-UF4 systems were assessed based on thermodynamic principles, and diverse thermodynamic models were adapted to different systems. Associate solution model (ASM) was used to describe the Gibbs energies of liquid phase of the NaF-BeF2 system, whereas other systems(NaF-ThF4 and NaF-UF4) were treated with the substitutional solution model(SSM) and intermediate compounds were described as stoichiometric compounds according to the Neumann-Kopp rule. All the thermodynamic model parameters were optimized by the least squares procedure until good coincidence was achieved between the calculated results and the experimental data. The derived thermodynamic parameters will be merged into the NaF-BeF2-ThF4-UF4 database to develop the thorium molten salt reactor(TMSR) project.

Thermodynamics of liquid Sn-Pb alloys determined by vapour pressure measurements

Application of Knudsen method in the studies of liquid Sn-Pb alloys, containing from 4.85 to 95.31mol% of lead, in temperatures from 851 to 1186K, and liquid tin and lead, in temperatures 1360 – 1442 and 934 – 1149K, respectively, provided experimental data which made characterization of thermodynamic properties of liquid phase of Sn-Pb system possible. Parameters of the Redlich-Kister equation, describing excess Gibbs energy of liquid phase of the examined system, were determined. With application of the third law method standard enthalpies of sublimation of tin and lead were calculated.

Thermodynamics of the Cu–Bi system determined by vapour pressure measurements

Application of Knudsen method for solid and liquid copper in the temperature range 1300–1725K, liquid bismuth in temperatures 769–1129K, and liquid Cu–Bi alloys in temperatures from 871 to 1469K, provided experimental data which made it possible to characterize thermodynamic properties of liquid and gaseous phase of Cu–Bi system. Standard enthalpies of copper and bismuth monomers sublimation and dissociation of bismuth dimer as well as parameters of Regular Associated Solution model (RAS), describing excess Gibbs energy of liquid phase of the examined system, were determined. The obtained model takes into account also presence of disturbances in vaporization of bismuth dimer from Cu–Bi alloys by introducing into the model a parameter which describes the evaporation coefficient of that particle.

Phase equilibria calculation of LaI 3-MI (M=Na, K, Cs) binary systems

The Gibbs energies of liquid phases in the LaI 3-MI (M= Na, K, Cs) systems were described by the modified quasi-chemical model. From the measured phase equilibrium data of these binary systems, a set of thermodynamic functions were optimized by using the CALPHAD technique. The enthalpy of mixing and the interaction parameter of the liquid phase were predicted from known data for the LaI 3-MI systems.

Thermodynamic Optimization and Calculation of the HoCl3-MCl (M = Na, K, Rb, Cs) Systems

According to measured experimental phase diagram data and thermodynamic data, the HoCl3-MCl (M = Na, K, Rb, Cs) phase diagrams were determined by the CALPHAD technique. The Gibbs energies of liquid phases in these systems have been optimized and calculated by the modified quasi-chemical model in the pair-approximation for short-range ordering. A series of thermodynamic functions have been optimized and calculated on the basis of an interactive computer-assisted analysis. The results show that the thermodynamic properties and phase diagrams are self-consistent. The optimized results for the systems are discussed.

Thermodynamic optimization and calculation of phase diagrams of YbCl 3-MCl (M=Na, K, Rb, Cs)

YbCl 3-MCl (M = Na, K, Rb, Cs) systems were optimized and calculated using the CALPHAD (CALculation of PHAse Diagram) technique. The modified quasi-chemical model in the pair-approximation for short-range ordering was used to describe the Gibbs energies of liquid phase in the systems. On the basis of the measured phase diagram data and experimental thermodynamic properties, a series of thermodynamic functions were optimized and calculated through an interactive computer-assisted analysis. Furthermore, some reasonable discussions on the thermodynamic parameters for these strong interaction binary systems were carried out. The results showed that the optimized parameters and experimental data are thermodynamically self-consistent.

Materials Design for the Fabrication of Porous Glass using Phase Separation in Multi-component Borosilicate Glass

Porous glass was fabricated using spinodal decomposition in multi-component oxide glass and leaching out one of the decomposed phases with acid solution. Multi-component borosilicate glass compositions were designed for the porous glass by partially replacing SiO2 by B2O3 in silicate glass compositions where the occurrence of spinodal decomposition was confirmed. One of separated phases formed by the spinodal decomposition in the borosilicate glass was leached out with acid solution and then porous glass was obtained. The microstructure in porous glass was observed by field emission scanning electron microscopy, and the development of an interconnected porous structure was indicated. Prediction of the phase separation was attempted for multi-component borosilicate glass compositions investigated in this study by calculating the Gibbs energy of super-cooled liquid phase. It was revealed the calculated metastable liquid–liquid immiscibility boundaries in these borosilicate systems do not coincide with experimental results for the occurrence of phase separation. For the precise estimation of the miscibility gap in the multi-component oxide glasses containing B2O3, the temperature and composition dependence of Gibbs energy of liquid phase, including the super-cooled liquid state, should be optimized.

Thermodynamic optimization of the DyCl3-KCl and DyCl3CaCl2 systems

From the measured phase diagram data and experimental thermochemical properties, the DyCl3-KCl and DyCl3-CaCl2, phase diagrams were optimized and calculated by the CALPHAD technique. The Gibbs energies of liquid phase in the two systems has been optimized and calculated by new modified quasi-chemical model in the pair-approximation for short-range ordering, and a series of thermodynamic functions has also been optimized based on an interactive computer-assisted analysis. The results showed that the calculated phase diagrams and thermodynamic data were self-consistent.

Optimization and Calculation of the EuCl3–MCl (M = Na, K, Rb, Cs) Phase Diagrams

By using the CALPHAD technique, an optimization of the binary EuCl3–MCl (M = Na, K, Rb, Cs) systems has been carried out. To describe the Gibbs energies of liquid phases in these systems the new modified quasi-chemical model was used in the pair-approximation for short-range ordering. From the measured phase equilibrium data and the experimental thermo-chemical properties, the EuCl3–MCl phase diagrams were optimized and calculated. A set of thermodynamic functions has been optimized based on an interactive computer-assisted analysis. The calculated phase diagrams and thermodynamic data are self-consistent.

Thermodynamic Assessment of the Miscibility Gaps and the Metastable Liquidi in the B2O3–RO Systems (R = Mg, Ca, Sr, and Ba)

In an attempt to understand the liquid–liquid phase separation in the B2O3–MgO, B2O3–CaO, B2O3–SrO, and B2O3–BaO systems, the liquid miscibility gaps were calculated using the optimized interaction parameters of liquid phases. The Gibbs energies of liquid phases were derived in the form of a subregular solution from an optimization procedure based on phase diagram data. In addition, metastable liquidus boundaries and spinodal curves were also assessed by using the Gibbs energies of liquid phases. The present results were compared and discussed with other experimental and assessed data available in the literature.

Thermodynamic optimization of the CeCl 3–AECl 2 (AE=Mg,Ca,Sr,Ba) phase diagrams

By using the CALPHAD technique, an optimization of the binary CeCl 3–AECl 2 (AE=Mg,Ca,Sr,Ba) systems has been carried out. For describing the Gibbs energies of liquid phase in these systems, the new modified quasichemical model in the pair-approximation for short-range ordering was used. From the measured phase equilibria data and experimental thermochemical properties, the CeCl 3–AECl 2 phase diagrams were optimized and calculated. A set of thermodynamic functions has been optimized based on an interactive computer-assisted analysis. The calculated phase diagrams and thermodynamic data are self-consistent.

Thermodynamic evaluation of the Cu-R (R: Ce, Pr, Nd, Sm) binary systems

The phase diagrams and thermodynamic properties of the Cu-R (R: Ce, Pr, Nd, Sm) systems are reevaluated on the basis of all available experimental data, including the enthalpies of mixing reported recently. The Redlich-Kister polynomial with two or three terms is used to describe the excess Gibbs energies of liquid phases in the Cu-R systems. All intermediate phases are treated as stoichiometric, and their Gibbs energies of formation are optimized. Based on the optimized thermodynamic parameters, phase diagrams and thermodynamic properties of the Cu-R systems are calculated and compared with the experimental results. The optimized parameters seem to be in good agreement with the experimental data and might represent the regularity and systematic variation of these systems.