Thermodynamic modeling of the Au-Sb-Si ternary system

Thermodynamic optimization of the Au-Sb binary system was updated as well as the Si-Sb binary system was assessed thermodynamically using the CALPHAD method based on the critical review of the available experimental information from the published literature. The solution phases including liquid, fcc_A1(Au), diamond_A4(Si) and rhombohedral_A7(Sb), are modeled as substitutional solutions and their excess Gibbs energies are expressed by a Redlich-Kister polynomial. The solubility of Si in the intermetallic compound AuSb₂ is not taken into account because of the lack of experimental information. Combined with previous assessment of the Au-Si binary system, thermodynamic modeling of the Au-Sb-Si ternary system was performed to reproduce well the measured phase equilibria. The liquidus projection and several vertical sections of this ternary system were calculated, which are in reasonable agreement with the reported experimental data.     

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     

Computational thermodynamic model for the Mg−Al−Y system

The ternary Mg−Al−Y system was thermodynamically modeled based on the optimization of the binary subsystems Mg−Al, Mg−Y, and Al−Y using the CALPHAD approach. Mg−Al data was taken from the COST507 database, whereas the other two binary systems were reoptimized in this work. The liquid phase was described by a Redlich-Kister polynomial model, and the intermediate solid solutions were described by a sublattice model. Ternary interaction parameters were introduced to enable the best representation of the experimental data while considering the occurrence of the ternary compound Al₄MgY. The constructed database is used to calculate and predict thermodynamic properties, binary phase diagrams of Al−Y and Mg−Y, and liquidus projections of the ternary Mg−Al−Y. The calculated phase diagrams and the thermodynamic properties are in good agreement with the corresponding experimental data from the literature. Sixteen ternary four-phase-equilibria invariant points were predicted in the Mg−Al−Y system: seven ternary eutectic points, eight ternary quasi peritectic points, and one ternary peritectic point. Further, fifteen three-phase-equilibria in variant points were determined: eight saddle points and seven binary eutectic points.     

Thermodynamic calculation of phase diagrams of the 60 common-ion ternary systems containing cations Li,Na, K,Rb, Cs and anions F,Cl, Br,I

The phase diagrams of all 60 possible common-ion ternary alkali halide systems were calculated thermodynamically. The thermodynamic properties of the ternary phases were calculated from the optimized properties of the binary subsystems, which were obtained from previously reported critical evaluations of binary data. Calculated ternary phase diagrams are compared with experimental diagrams in those 47 systems for which the latter are available. In most cases, agreement is within experimental error limits. For five systems, a small empirical correction term was added to the Gibbs energy expression in order to bring the calculated and reported diagrams into coincidence. The calculated ternary diagrams are considered to be the best evaluated diagrams that can be deduced from currently available data. A probable maximum inaccuracy was estimated for each system.     

Thermodynamic calculation of phase diagrams of the 60 common-ion ternary systems containing cations Li, Na, K, Rb, Cs and anions F, Cl, Br, I

The phase diagrams of all 60 possible common-ion ternary alkali halide systems were calculated thermodynamically. The thermodynamic properties of the ternary phases were calculated from the optimized properties of the binary subsystems, which were obtained from previously reported critical evaluations of binary data. Calculated ternary phase diagrams are compared with experimental diagrams in those 47 systems for which the latter are available. In most cases, agreement is within experimental error limits. For five systems, a small empirical correction term was added to the Gibbs energy expression in order to bring the calculated and reported diagrams into coincidence. The calculated ternary diagrams are considered to be the best evaluated diagrams that can be deduced from currently available data. A probable maximum inaccuracy was estimated for each system.     

Experimental Investigation and Thermodynamic Calculation of the Phase Equilibria in the Al-Bi-Sn Ternary System

This work first deals with the experimental investigation and thermodynamic calculation in the Al-Bi-Sn ternary system. The phase equilibria at 400 and 500 °C in the Al-Bi-Sn ternary system have been experimentally determined by electron probe microanalysis (EPMA) on the equilibrated alloys. Based on the experimental data determined in the present work, the phase equilibria in the Al-Bi-Sn ternary system have been thermodynamically assessed by using the CALPHAD (CALculation of PHAse Diagrams) method, and a consistent set of thermodynamic parameters leading to reasonable agreement between the calculated results and experimental data was obtained. The additions of Sn can effectively reduce the stable liquid miscibility gap in the Al-Bi binary system and gradually decrease its critical temperature. And the additions of Bi can significantly stabilize the metastable liquid miscibility gap in the Al-Sn binary system. This is shown by an initial decrease in critical temperature with increasing Bi additions.     

Thermodynamic and experimental study of Ti---Ag---Cu alloys

Phase equilibria in the ternary Ti---Ag---Cu system have been studied thermodynamically and experimentally at various temperatures. The thermodynamic analysis was performed by combining the most recent data on the binary Ag---Cu, Ti---Ag and Ti---Cu systems and experimental information obtained by the diffusion couple technique. The eutectic and three non-eutectic binary Ag---Cu alloys were melted and annealed in evacuated Ti ampoules at temperatures of 900, 950 and 1000 °C for various times and subsequently quenched in water. Both the calculations and the experimental results confirm that in the ternary system there is a miscibility gap, which divides the liquid phase into solutions of low and high Ti content. Furthermore, no ternary compounds were found. Several isothermal sections and the activity of titanium as a function of the copper-to-silver ratio and temperature are presented.     

Diffusivities of an Al–Fe–Ni melt and their effects on the microstructure during solidification

A systematical investigation of the diffusivities in an Al–Fe–Ni melt was presented. Based on the experimental and theoretical data about diffusivities, the temperature- and composition-dependent atomic mobilities were evaluated for the elements in Al–Ni, Al–Fe, Fe–Ni and Al–Fe–Ni melts via an effective approach. Most of the reported diffusivities can be reproduced well by the obtained atomic mobilities. In particular, for the first time the ternary diffusivity of the liquid in a ternary system is described in conjunction with the established atomic mobilities. The effect of the atomic mobilities in a liquid on microstructure and microsegregation during solidification was demonstrated with one Al–Ni binary alloy. The simulation results indicate that accurate databases of mobilities in the liquid phase are much needed for the quantitative simulation of microstructural evolution during solidification by using various approaches, including DICTRA and the phase-field method.     

Experimental Investigation and Thermodynamic Calculation of the Phase Equilibria in the Bi-Cu-Zn Ternary System

The phase equilibria of the Bi-Cu-Zn ternary system has been firstly and comprehensively investigated by electron probe microanalyzer (EPMA) with equilibrated alloys. Two isothermal sections of the Bi-Cu-Zn ternary system at 500 and 650 °C were determined. Based on the experimental data of phase equilibria, the Bi-Cu-Zn ternary system was also thermodynamically optimized using the Calculation of Phase Diagrams (CALPHAD) method. The experimental result shows that Bi is almost insoluble in the Cu-Zn binary compounds and (Cu) phase. It is found that the critical temperatures of the miscibility gaps in the Bi-Cu and Bi-Zn binary systems gradually increase with the increasing of the third element Zn or Cu additions. Moreover, the composition range of the liquid miscibility gap gradually reduces with the temperature increasing.     

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.     

Thermodynamic assessment on the Pb–Ca–Sn ternary system

Thermodynamic modelling of the Pb–Ca–Sn ternary system was carried out with the help of the CALculation of PHase Diagrams (CALPHAD) method.The binary borders related to the ternary system were investigated. The lead–tin system is already calculated, the calcium–tin and calcium–lead systems can be described with the association model in binary liquid. The establishment of the modelling of the Pb–Ca–Sn phase diagram was done after collecting own experimental information. The introduction of new interaction parameters related to the ternary liquid, leads to an accurate restoration of the experimental data.Calculated isothermal, isoplethal sections and liquidus surfaces are presented. They confirm that the calcium solubility in lead matrix drastically decreases with the introduction of tin as well as with the decreasing of temperature. The industrial process applied to the lead–calcium–tin alloys finds some justifications in the calculated phase diagram.     

Thermodynamic Assessment of Zn-Fe-Nb Ternary System

The Nb-Zn binary system has been thermodynamically assessed using CALPHAD approach by combining available experimental data and the data from ab initio calculations of the formation enthalpies for NbZn₂, NbZn₃ and NbZn₁₅. Solution phases including Liquid, Bcc, Hcp were modeled as substitutional phases, of which the excess Gibbs energies being formulated with the Redlich-Kister polynomial function. All the binary compounds were treated as stoichiometric phases. Incorporated with the reported thermodynamic parameters of Fe-Zn and Fe-Nb binary systems, two isothermal sections at 723 and 873 K of Zn-Fe-Nb ternary system were thermodynamically optimized where one stoichiometric ternary phase (τ) and the ternary solubility in intermetallic compound (ε) were taken into consideration. Furthermore, liquidus projection was predicted accordingly.     

EQUILIBRIUM PHASE DIAGRAMS IN SYSTEM CuO-PbO-Ag

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Thermodynamic Assessment of the Al-Ba System

The Al-Ba was thermodynamically optimized with the help of CALPHAD method. The solution phases such as liquid, fcc and bcc phases were modeled as substitutional solution phases. The excess Gibbs energies of these phases were treated with Redlich-Kister polynomial functions. A set of self-consistent thermodynamic parameters for describing various phases in the Al-Ba system was obtained, which can well reproduce the corresponding experimental data. The Al-Ba-Ni ternary system were also extrapolated based on the present binary system.     

Thermodynamic optimization of the boron-cobalt-iron system

A thermodynamic optimization of the boron-cobalt-iron ternary system is performed based on thermodynamic models of the three constitutional binary systems and the experimental data on phase diagrams and thermodynamic properties of the ternary system. The liquid, fcc_A1, bcc_A2 and hcp_A3 solution phases are described by the substitutional solution model. The three intermediate line compounds, (Co,Fe)B, (Co,Fe)₂B and (Co,Fe)₃B, are described by the two sublattice model. A set of thermodynamic parameters are obtained. The calculated phase diagram and thermodynamic properties are in reasonable agreement with most of the experimental data.     

Thermodynamics and mechanism of demixing in undercooled Cu–Co–Ni alloys

This work deals with the effect of Ni addition on the liquid–liquid phase separation in the Cu–Co system which displays a liquid metastable miscibility gap. Cu–Co–Ni samples with different compositions have been processed by differential scanning calorimetry using a fluxing technique to precisely determine transformation temperatures. The ternary phase diagram has been evaluated by Calphad, extrapolating the binary systems and optimizing ternary parameters using the experimental results of the present work. Ni additions reduce the demixing temperature, bringing the binodal line below the peritectic. The mechanisms of demixing and formation of microstructures have been clarified for low and high Ni content.