Phase diagram of Fe-Cu-Si ternary system above 1523 K

Fe-Cu-Si ternary alloy phases are commonly formed during melting in a treatment process of domestic waste incineration that is currently being developed. The alloy phases appear in the incineration residue. Experiments were performed to observe phase equilibria in solid Fe+liquid, solid Si+liquid, the compound of FeSi liquid, and so forth, in the range 1523 to 1723 K. Then the phase diagram of Fe-Cu-Si ternary was thermodynamically assessed based on the present experimental results and literature data. It was found that this system has a wide liquid miscibility gap, and this two-liquid region is stable up to about 1900 K. The phase diagram of Fe-Cu-Si system assessed in the present work is much different from an earlier proposed diagram, but is very close to one recently evaluated. From the results obtained, the appropriate condition is discussed for the operation of the melting furnace for ash from municipal solid waste incinerators.     

Critical evaluation and optimization of the thermodynamic properties and phase diagrams of the Al-Mg, Al-Sr, Mg-Sr, and Al-Mg-Sr Systems

All available thermodynamic and phase diagram data were critically assessed for all phases in the Al-Mg, Al-Sr, and Mg-Sr systems at 1 bar pressure from room temperature to above the liquidus temperatures. For these systems, all reliable data were simultaneously optimized to obtain a set of model equations for the Gibbs energy of the liquid alloy and all solid phases as functions of composition and temperature. The modified quasi-chemical model was used for the liquid. The Al-Mg-Sr ternary phase diagram was calculated from the optimized thermodynamic properties of the binary systems. Since no reliable ternary data were available, three assumptions were made: no ternary terms were added to the model parameters for the thermodynamic properties of the liquid, no ternary solid solutions are present in the system, and no ternary compound is present in the system. The calculated ternary phase diagram is thus a first approximation, which can be improved by the addition of new experimental data and can be used as a base for the calculation of phase diagrams of multicomponent systems.     

Processes at the liquid/crystal boundary upon contact melting in the system with intermediate solid phases

Growth of the liquid interlayer in the indium-tin system at 400 K in the process of contact melting in the nonstationary diffusion regime has been investigated experimentally. The contact pairs were composed of pure substances, solid solutions, and intermediate solid phases. The previously developed concepts have been extended to include the case where the existence of intermediate solid phases on both sides of the liquid phase should be taken into account. It follows from the results obtained that the concentration range of the liquid interlayer corresponds to the homogeneity range of the liquid phase in the phase diagram at the temperature of experiments. The results of the experiments can be explained based on the model according to which solid solutions and intermediate solid phases at the liquid/crystal interface arise due to the precipitation from the metastable melt supersaturated by the substance of the adjacent phase.     

Mg-Zn-Si体系的相平衡计算及应用

利用Calphad方法重新评估了Mg-Si二元系的液相,并结合Mg-Zn和Zn-Si二元系热力学数据,外推得到Mg-Zn-Si三元系热力学参数;同时根据Mg2Si-MgZn2伪二元相图实验数据评估了Mg-Zn-Si系的液相三元相交互作用参数,计算相图与实验数据较一致。利用Scheil凝固模型模拟了Mg-2.33Zn-0.9Si(at%)合金的凝固过程,预测了镁合金在铸造冷却过程中的相演变信息,模拟计算结果与实验结果吻合较好     

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.     

Thermodynamic modeling of Al–Ce–Mg phase equilibria coupled with key experiments

The ternary Al–Ce–Mg phase diagram was calculated using the Calphad method and investigated with selected key experiments. Arc melted alloys were annealed at 400 °C for 500 h and the phases were analyzed using quantitative X-ray powder diffraction (XRD). Differential thermal analysis (DTA) was also performed on an alloy with a composition near the ternary phase Al₁₃CeMg₆ (τ). Temperatures above 1000 °C could be attained due to a special sealing of the sample under argon by welding in a tantalum crucible to avoid evaporation and oxidation. Only with this procedure could reproducible and reliable DTA signals be obtained. The present experimental investigation and the consistent thermodynamic calculation show that the “ternary phase” Ce(Mg,Al)₂, seemingly isolated in the ternary at 400 °C, can be rationalized as a single solid solution phase between the binary end members if a larger temperature range and a solid state miscibility gap is considered. It is demonstrated that previously reported low values of ternary liquidus temperatures must be related to other phase equilibria. The actually found ternary liquidus temperatures are much higher and widely governed by the high melting compound Ce(Al,Mg)₂ and also by Al₁₁Ce₃ with primary solidification fields stretching far into the ternary system.     

Experimental analysis and thermodynamic calculation of the structural regularities in the fusion diagram of the system of alloys Al-Mg-Si

Sections of the phase diagram Al-Mg-Si with up to 35 at.% magnesium and 35 at.% silicon are constructed. The thermodynamic calculation and experimental analysis have shown that the conode of three-phase eutectic equilibrium L ⇔ α-Al+Mg₂Si, corresponding to the maximum temperature of eutectic transformation, does not coincide with the stoichiometric cross section between Al and Mg₂Si in the Al-Mg-Si ternary system, but rather occurs toward the magnesium-rich side of the ternary diagram. A polythermal cross section, corresponding to this conode, has been constructed. Concentration-temperature parameters of the univariant eutectic transformation L ⇔ α-Al+Mg₂Si, as well as the boundaries of the domain of existence of alloys crystallizing with the formation of only two phases, namely, α-Al and Mg₂Si, were determined. Modeling of phase equilibria involving solid and liquid phases in the ternary system Al-Mg-Si was carried out. The topology of the phase diagram is stable against a wide range variation of the adjustable parameters; the inherent form of the diagram seems well established. The reasons for this are discussed.     

Experimental analysis and thermodynamic calculation of the structural regularities in the fusion diagram of the system of alloys Al-Mg-Si

Sections of the phase diagram Al-Mg-Si with up to 35 at.% magnesium and 35 at.% silicon are constructed. The thermodynamic calculation and experimental analysis have shown that the conode of three-phase eutectic equilibrium L ⇔ α-Al+Mg₂Si, corresponding to the maximum temperature of eutectic transformation, does not coincide with the stoichiometric cross section between Al and Mg₂Si in the Al-Mg-Si ternary system, but rather occurs toward the magnesium-rich side of the ternary diagram. A polythermal cross section, corresponding to this conode, has been constructed. Concentration-temperature parameters of the univariant eutectic transformation L ⇔ α-Al+Mg₂Si, as well as the boundaries of the domain of existence of alloys crystallizing with the formation of only two phases, namely, α-Al and Mg₂Si, were determined. Modeling of phase equilibria involving solid and liquid phases in the ternary system Al-Mg-Si was carried out. The topology of the phase diagram is stable against a wide range variation of the adjustable parameters; the inherent form of the diagram seems well established. The reasons for this are discussed.     

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.     

The ternary Gd-Li-Mg system: Phase diagram study and computational evaluation

The binary Gd-Li and the ternary Gd-Li-Mg systems were studied experimentally by thermal analysis and phase equilibration and also by thermodynamic calculations using the CALPHAD method. Ternary phase equilibria at 250 °C were studied with 55 different alloys that were annealed for 400 h and analyzed by x-ray diffractometry. A thermodynamic assessment of the binary Gd-Li system was also performed and the calculated phase diagram is presented. In the Gd-Li-Mg system, ternary solubilities of Li in GdMg (up to 5 at.% Li), GdMg₂ (up to approximately 3 at.% Li), and GdMg₃ (up to 5 at.% Li) were found at 250 °C. No ternary compound was observed. Lattice parameters for different compositions are given for these phases. Thermal analysis using a ternary key sample of composition near the invariant reaction L′=L+(βGd)+GdMg provided the data that were needed to determine a thermodynamic parameter for the ternary liquid. Thermodynamic data sets for the ternary solid solution phases were also developed. Based on the present data sets and those of the binary Gd-Mg and Li-Mg systems from the literature, the phase equilibria in the entire ternary system were calculated. Isothermal and vertical sections of the phase diagram and the projection of the liquidus surface are shown. These calculated phase diagrams are well supported by the experimental data.     

The ternary Gd-Li-Mg system: Phase diagram study and computational evaluation

The binary Gd-Li and the ternary Gd-Li-Mg systems were studied experimentally by thermal analysis and phase equilibration and also by thermodynamic calculations using the CALPHAD method. Ternary phase equilibria at 250 °C were studied with 55 different alloys that were annealed for 400 h and analyzed by x-ray diffractometry. A thermodynamic assessment of the binary Gd-Li system was also performed and the calculated phase diagram is presented. In the Gd-Li-Mg system, ternary solubilities of Li in GdMg (up to 5 at.% Li), GdMg₂ (up to approximately 3 at.% Li), and GdMg₃ (up to 5 at.% Li) were found at 250 °C. No ternary compound was observed. Lattice parameters for different compositions are given for these phases. Thermal analysis using a ternary key sample of composition near the invariant reaction L′=L+(βGd)+GdMg provided the data that were needed to determine a thermodynamic parameter for the ternary liquid. Thermodynamic data sets for the ternary solid solution phases were also developed. Based on the present data sets and those of the binary Gd-Mg and Li-Mg systems from the literature, the phase equilibria in the entire ternary system were calculated. Isothermal and vertical sections of the phase diagram and the projection of the liquidus surface are shown. These calculated phase diagrams are well supported by the experimental data.     

A thermodynamic reassessment of the Al-As-Ga system

The Al-As-Ga system is one of the most important III-V mixed crystal systems because of its advantages as a heterostructure. There are more phase equilibria data available for this system over a wider range of temperatures and compositions, than for any other III-V ternary system. In this paper, the experimental phase diagram data of the Al-As-Ga ternary system have been assessed comprehensively and critically. Especially, the most recent experiments are considered. The interaction parameters of the liquid phase and the semiconductor compound are provided. With the assessed thermodynamic parameters, the pseudobinary AlAs-GaAs phase diagram, the Al-As-Ga ternary isothermal sections, and the solidus isoconcentration curves were calculated and compared with the related experimental data.     

A thermodynamic reassessment of the Al-As-Ga system

The Al-As-Ga system is one of the most important III-V mixed crystal systems because of its advantages as a heterostructure. There are more phase equilibria data available for this system over a wider range of temperatures and compositions, than for any other III-V ternary system. In this paper, the experimental phase diagram data of the Al-As-Ga ternary system have been assessed comprehensively and critically. Especially, the most recent experiments are considered. The interaction parameters of the liquid phase and the semiconductor compound are provided. With the assessed thermodynamic parameters, the pseudobinary AlAs-GaAs phase diagram, the Al-As-Ga ternary isothermal sections, and the solidus isoconcentration curves were calculated and compared with the related experimental data.