Thermodynamic Assessment of the Al-Mn and Mg-Al-Mn Systems

The binary Al-Mn system has been critically evaluated based upon available phase equilibrium and thermodynamic data, and optimized model parameters have been obtained giving the Gibbs energies of all phases as functions of temperature and composition. The liquid solution has been modeled with the modified quasichemical model to account for short-range ordering. The results have been combined with those of our previous optimizations of the Al-Mg and Mg-Mn systems to evaluate and optimize the Mg-Al-Mn system. All available data for the ternary system are reproduced with only one small ternary model parameter for the liquid phase.     

Assessment of the Te-Tl (tellurium-thallium) system

The optimized thermodynamic data for the Te- TI binary system have been obtained by the computer operated least squares method from measured data. The Gibbs energy of the liquid phase was modeled as a two- sublattice model for ionic melt after Hillert.³¹ The intermediate compounds, Te₃Tl{2}and TeTl, were treated as stoichiometric phases, and the nonstoichiometric γ phase was expressed as a sublattice model. A strong tendency for chemical short- range order in the liquid state at the composition close to TeTh was confirmed by calculated results, but the existence of the TeTh phase was not justified. The experimental thermodynamic and phase diagram data were closely reproduced by the optimized thermodynamic data. Parameters describing the Gibbs energies of all the phases in this calculation and the calculated phase diagram and thermodynamic functions are presented and compared with experimental information.     

A thermodynamic assessment of the Al-Cu-Mg ternary system

A thermodynamic assessment of the Al-Cu-Mg ternary system is presented. The Gibbs energies for the liquid and solid solution phases were modeled using the Redlich-Kister polynomial and the Wagner-Schottky model represented by the compound-energy formalism. The model parameters were obtained after fitting to previously critically assessed experimental phase diagram and thermodynamic data available in the literature. The thermodynamic functions and phase diagram calculated using the model parameters describe quite well the known experimental information. The complete set of Gibbs energies for all phases appearing in this system enables the calculation of thermodynamic values as a function of composition and temperature even for those ranges where no experimental information is available.     

Assessment of the Te-Tl (tellurium-thallium) system

The optimized thermodynamic data for the Te- TI binary system have been obtained by the computer operated least squares method from measured data. The Gibbs energy of the liquid phase was modeled as a two- sublattice model for ionic melt after Hillert.³¹ The intermediate compounds, Te₃Tl{2}and TeTl, were treated as stoichiometric phases, and the nonstoichiometric γ phase was expressed as a sublattice model. A strong tendency for chemical short- range order in the liquid state at the composition close to TeTh was confirmed by calculated results, but the existence of the TeTh phase was not justified. The experimental thermodynamic and phase diagram data were closely reproduced by the optimized thermodynamic data. Parameters describing the Gibbs energies of all the phases in this calculation and the calculated phase diagram and thermodynamic functions are presented and compared with experimental information.     

Thermodynamic Evaluation and Optimization of the SrO-MgO,SrO-SiO<Subscript>2</Subscript> and SrO-MgO-SiO<Subscript>2</Subscript> Systems

The SrO-MgO and SrO-SiO₂ systems have been critically evaluated based upon available phase equilibrium and thermodynamic data, and optimized model parameters have been obtained giving the Gibbs energies of all phases as functions of temperature and composition. The liquid solution has been modeled with the Modified Quasichemical Model to account for short-range-ordering. The results have been combined with those of previous optimizations of the MgO-SiO₂ system in the optimization of the SrO-MgO-SiO₂ system.     

Critical Evaluation and Thermodynamic Optimization of the Binary Systems in the Mg-Ce-Mn-Y System

Critical evaluation and thermodynamic optimization have been carried out for the Mg-Ce, Mg-Mn, Mg-Y, Ce-Mn, Ce-Y, and Mn-Y binary systems. All phase diagrams and thermodynamic data such as enthalpies of mixing, heats of formation, etc., were considered to obtain one set of model parameters of the Gibbs energies of all phases, which can reproduce the experimental data within experimental error limits. For the liquid alloys, the Modified Quasi-chemical Model in the pair approximation was used to treat short-range-ordering.     

Thermodynamic modeling of the Ce–Zn and Pr–Zn systems

In order to develop the thermodynamic database of phase equilibria in the Mg–Zn–Re (Re: rare earth element) base alloys, the thermodynamic assessments of the Ce–Zn and Pr–Zn systems were carried out by using the calculation of phase diagrams (CALPHAD) method on the basis of the experimental data including thermodynamic properties and phase equilibria. Based on the available experimental data, Gibbs free energies of the solution phases (liquid, bcc, fcc, hcp and dhcp) were modeled by the subregular solution model with the Redlich–Kister formula, and those of the intermetallic compounds were described by the sublattice model. A consistent set of thermodynamic parameters has been derived for describing the Gibbs free energies of each solution phase and intermetallic compound in the Ce–Zn and Pr–Zn binary systems. An agreement between the present calculated results and experimental data is obtained.     

Thermodynamic optimization of Mg-Nd system

Based on the reported experimental data,the phase diagram of Mg-Nd binary system was optimized using the CALPHADapproach.Gibbs energies of the disordered BCC_A2 and ordered BCC_B2 phases were modeled with a single expression based on a2-sublattice model.Liquid and terminal solutions,such as dHCP and HCP,were modeled as substitutional solutions.Intermediatephases Mg2Nd,Mg3Nd and Mg41Nd5 were treated as stoichiometric compounds.The optimization was carried out in theThermo-Calc package.A set of thermodynamic parameters is obtained.Calculated phase diagram,enthalpies of formation and Gibbsenergies of formation are in reasonable agreement with the experimental data.     

Cu-Ni-Sn三元系相平衡的热力学计算

基于Cu-Ni-Sn三元系的相平衡和热力学的实验信息,采用亚正规溶体模型描述液相和fcc相的Gibbs自由能,为了预测该体系中bcc相的A2-B2有序-无序转变,bcc相的Gibbs自由能采用双亚点阵模型进行描述.利用CALPHAD(相图计算)方法评估了Cu-Ni-Sn三元系各相的热力学参数,计算的富Cu侧相图和热力学性质与实验数据比较一致.并对该三元系中bcc相的A2-B2有序-无序转变及fcc相的溶解度间隙进行了计算.这些计算结果对利用析出强化以及Spinodal分解开发高强度和高导电性的新型Cu基合金的组织设计具有一定的指导意义.     

Thermodynamic assessments of Ag–Dy and Ag–Er binary systems

Thermodynamic assessments of Ag–Dy and Ag–Er binary systems have been performed by using CALPHAD method. In order to provide necessary data for thermodynamic assessment, the formation enthalpies of Ag₂Dy, AgDy, Ag₂Er and AgEr were calculated by using projector augmented-wave (PAW) method within generalized gradient approximation (GGA) in first-principles frame. During assessments of the Ag–Dy and Ag–Er binary systems, the solution phases (liquid, fcc and hcp) were treated as substitutional solutions, of which the excess Gibbs energies were modeled by Redlich–Kister polynomial, and all intermetallic compounds were described as stoichiometric phases. Consequently, phase diagrams of these two binary systems were thermodynamically optimized and the self-consistent thermodynamic parameters of involved phases obtained.     

Thermodynamic assessment of the Ni-Sb binary system

The Ni-Sb binary alloy system was thermodynamically assessed using CALPHAD approach in this article.Excess Gibbs energies of solution phases,liquid and fcc phases,were formulated using the Redlich-Kister expression.The intermediate phases were modeled by the sublattice model with (Ni,Va)0.5(Ni,Sb)0.25(Ni)0.25 for Ni3Sb_HT phase and (Ni,Va)0.3333(Sb)0.3333(Ni,Va)0.3333 for NiSb phase.The other phases including Ni3Sb,Ni7Sb3,and NiSb2 were treated as stoichiometric compound owing to their narrow composition ranges.Based on the reported thermodynamic properties and phase diagram data,the thermodynamic parameters of these phases were optimized,and the obtained values can reproduce the available experimental data well.     

Thermodynamic Assessment of the Ti-Ir System

The thermodynamic assessment of the binary system Ti-Ir has been carried out by modeling the Gibbs energy of all individual phases using the calculation of phase diagrams approach based on the available literature data including the phase equilibria and thermodynamic properties. The Gibbs free energies of the liquid, bcc, fcc and hcp phases were described by the subregular solution model with Redlich-Kister formula, and those of the intermetallic compounds (Ti₃Ir, γTiIr, βTiIr and TiIr₃) in the Ti-Ir binary system were described by the two-sublattice model. The calculations are in good agreement with the literature data on both phase equilibria and thermodynamic properties in the Ti-Ir system.     

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 assessment of the Ga–Sc and Ga–Tb systems

The Ga–Sc and Ga–Tb binary systems have been assessed with CALPHAD method. Liquid is treated as substitutional solution phase, of which the excess Gibbs energies are modeled by Redlich–Kister polynomial function. The binary intermetallic compounds are treated as stoichiometric phases. Thermodynamic parameters of various phases have been optimized and the calculated results are in reasonable agreement with experimental data.     

Thermodynamic database of the phase diagrams in the Mg-Al-Zn-Y-Ce system

The Mg-Al-Zn-Y-Ce system is one of the key systems for designing high-strength Mg alloys. The purpose of the present article is to develop a thermodynamic database for the Mg-Al-Zn-Y-Ce multicomponent system to design Mg alloys using the calculation of phase diagrams （CALPHAD） method, where the Gibbs energies of solution phases such as liquid, fcc, bcc, and hcp phases were described by the subregular solution model, whereas those of all the compounds were described by the sublattice model. The thermodynamic parameters describing Gibbs energies of the different phases in this database were evaluated by fitting the experimental data for phase equilibria and thermodynamic properties. On the basis of this database, a lot of information concerning stable and metastable phase equilibria of isothermal and vertical sections, molar fractions of constituent phases, the liquidus projection, etc., can be predicted. This database is expected to play an important role in the design of Mg alloys.     

Thermodynamic database of the phase diagrams in Cu-Fe base ternary systems

A thermodynamic database of the Cu-Fe-X [X: aluminum (Al), cobalt (Co), chromium (Cr), manganese (Mn), molybdenum (Mo), niobium (Nb), nickel (Ni), vanadium (V)] systems was developed by the CALPHAD (Calculation of Phase Diagrams) method, where the Gibbs energies of solution phases such as the liquid, face-centered-cubic (fcc), body-centered-cubic (bcc), and hexagonal-close-packed (hcp) phases are described by the subregular solution model, while the those of the bcc phase in the Cu-Fe-Al system and of all compounds are described by the sublattice model. The thermodynamic parameters describing Gibbs energies of the different phases in this database were evaluated by fitting the experimental data for phase equilibria and thermodynamic properties. On the basis of this database, much information concerning stable and metastable phase equilibria of isothermal and vertical sections, molar fractions of constituent phases, the liquidus projection, etc., can be predicted. This database is expected to play an important role in the design of Cu-Fe base alloys.     

Experimental studies and thermodynamic optimization of the Ni-Bi system

Experimental studies by electron microprobe analyses, optical microscopy, and differential scanning calorimetry were performed. New data about the liquidus in the central and the Bi-rich regions were obtained. A narrow homogeneity region (about 50–52 at.% Bi) was found for the compound NiBi while the second intermediate phase in this system (NiBi₃) was stoichiometric. Thermodynamic optimization of the Ni-Bi phase diagram was achieved by the CALPHAD method by combining phase diagram and thermodynamic data. Thus, NiBi was modeled with two sublattices, allowing mixing of Bi and Ni on one of them only. The intermetallic phase NiBi₃ was modeled as a stoichiometric compound. Redlich-Kister polynomials were used to describe the excess Gibbs energies of the solution phases (liquid, pure bismuth, and Ni-based solid solutions).     

CALCULATION OF THERMODYNAMIC PROPERTIES AND PHASE DIAGRAM OF TERNARY MOLTEN SALT SYSTEM NaCl-CaCl_2-SrCl_2 BY USE OF COMPUTOR

本文利用 CaCl-SrCl_2相图中,固相有一个溶解间断区(miscibility gap)的信息,用亚正规溶液模型计算了该二元系液相和固相的 Gibbs 自由能.运用 Toop方程的变通式即最近 Hillert.M.提出的新的非对称方法,由组成 NaCl-CaCl_2-SrCl_2三元系的二元系热力学性质预示了该三元系液相的 Gibbs 自由能,进而用计算机计算了三元液相中各组元的偏克分子 Gibbs 自由能和活度系数.由三元液相中组元 NaCl,CaCl_2和 SrCl_2的过剩偏克分子 Gibbs 自由能,根据相平衡原理,用计算机计算了该三元系的相图.计算结果对于钠电解的实践和盐湖资源的综合利用有实际意义.亚正规溶液模型和新的非对称方法可望适合于计算一系列有潜在重要性的电荷不对称熔盐体系的相图.如对 Na,Ti,Mg,Ce 电解及熔融氯化脱水制取无水氯化镁有实际意义的 NaCl-CaCl_2-BaCl_2,NaCl-SrCl_2-BaCl_2,NaCl-CaCl_2-MgCl_2,KCl-CaCl_2-MgCl_2,KCl-NaCl-CeCl_3等三元相图.