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     

Experimental Investigation and Thermodynamic Calculation of Phase Equilibria in the Mg-Pb-Sn Ternary System

The phase equilibria of the Mg-Pb-Sn ternary system were investigated using a combined method of electron probe microanalyzer and x-ray diffraction. Three isothermal sections of the Mg-Pb-Sn ternary system at 200, 300 and 400 °C were experimentally established. The phase equilibria of Mg-Pb-Sn ternary system were thermodynamically assessed by using CALPHAD (Calculation of Phase Diagrams) method on the basis of the presently determined experimental data. A consistent set of thermodynamic parameters has been derived for describing the Gibbs free energies of each solution phase and intermetallic compound in the Mg-Pb-Sn ternary system. The calculated phase diagrams and thermodynamic properties in the Mg-Pb-Sn ternary system are in good agreement with experimental data.     

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.     

Experimental Investigation and Thermodynamic Calculation of the Phase Equilibria in the Cu-Nb-Zr Ternary System

The phase equilibria of the Cu-Nb-Zr ternary system at 900, 1000 and 1100 °C were experimentally investigated by optical microscopy and electron probe microanalysis on the equilibrated alloys. Combined with the obtained experimental results, the phase equilibria of Cu-Nb-Zr ternary system were thermodynamically optimized using the CALPHAD (calculation of phase diagrams) method. The Gibbs free energies of the phases in the present work were described by appropriate models. A consistent set of the thermodynamic parameters leading to reasonable agreement between the calculated data and experimental results was obtained in the Cu-Nb-Zr ternary 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.     

Experimental Investigation and Thermodynamic Calculation of the Phase Equilibria in the Cr-Hf-Ti Ternary System

The phase equilibria of the Cr-Hf-Ti ternary system has been firstly investigated by electron probe micro-analyzer, x-ray diffraction and differential scanning calorimetry on equilibrated alloys. Three isothermal sections of the Cr-Hf-Ti ternary system at 1100, 1200 and 1300 °C were determined. Meanwhile, this ternary system was also thermodynamically optimized using the calculation of phase diagrams method. The calculated result replies that the existing temperature range of the C15 (Cr₂Hf) increased due to addition of the third element Ti.     

Experimental Investigation and Thermodynamic Calculation of the Phase Equilibria in the Co-Cu-V Ternary System

The phase equilibria of the Co-Cu-V ternary system at 900, 1000, 1100 and 1200 °C have been experimentally determined by optical microscopy and electron probe micro-analysis of the equilibrated alloys. The phase transformations were investigated by means of the differential scanning calorimetry. Based on the experimental data of phase equilibria and thermodynamic properties, the thermodynamic assessment of the Co-Cu-V ternary system was carried out by using the calculation of phase diagrams method. A consistent set of the thermodynamic parameters leading to reasonable agreement between the calculated results and experimental data was obtained in the Co-Cu-V ternary system. Meanwhile, the calculated results show that the critical temperature of metastable magnetically induced miscibility gap of (α _f Co) and (α _p Co) phases in the Co-V system gradually decreases with increasing Cu composition in the range of 0-3 wt.% additions.     

Solid-State Phase Equilibria of the Cu-S System: Thermodynamic Modeling

All phase equilibria and thermodynamic data available in the literature on the copper sulfides high- and low-temperature chalcocite, djurleite and anilite have been critically analyzed for optimization of the solid-state phase diagram of the Cu-S system at 1 bar total pressure. A two-sublattice approach derived from a recently developed Gibbs energy model for digenite enables the consideration of the solid solution nature of both modifications of chalcocite and for the first time of djurleite. Anilite is considered as stoichiometric compound. The sulfur solubility of metallic copper is described by a substitutional approach. The obtained Gibbs energy functions for high- and low-temperature chalcocite, djurleite, anilite and copper alloy phase allow computations and predictions of phase equilibria and thermodynamic properties in good accordance with experimental data of the Cu-S solid-state system.     

Experimental Investigation and Thermodynamic Calculation of the Phase Equilibria in the Cu-Cr-W and Cu-Cr-Mo Systems

Phase equilibria of the Cu-Cr-W and Cu-Cr-Mo systems were experimentally determined by using metallography, X-ray diffraction (XRD) and electron probe micro-analyzer (EPMA) techniques. Based on the experimental data determined by the present work, the thermodynamic assessments of the Cu-Cr-W and Cu-Cr-Mo systems were carried out by using CALPHAD method. A consistent set of the thermodynamic parameters has been obtained, which leaded to a good fit between calculated results and the experimental data in both the Cu-Cr-W and Cu-Cr-Mo systems.     

Phase Equilibria Calculation of the Ga-In-Sb Ternary System

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Experimental and Thermodynamic Analysis on Phase Equilibria of Ni-rich Region in Ni-Al-Ti System

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Phase Equilibria in the Fe-Nb System

A review of the literature revealed that recently published phase diagrams of the Fe-Nb system show considerable discrepancies regarding phase equilibria with the melt and the homogeneity ranges of the intermetallic phases, specifically of the Laves phase Fe₂Nb. Therefore the system has been reinvestigated by metallography, electron probe microanalysis (EPMA), and differential thermal analysis (DTA). Temperatures of invariant reactions were determined and the homogeneity ranges of the two intermetallic phases, Fe₂Nb Laves phase and Fe₇Nb₆ μ phase, which both exist within a wide composition range, were established.     

Al-Cu-Mg合金相图的计算

应用Levenberg-Marquardt(LM)算法进行了Al-Cu-Mg三元合金相图的计算.计算所得的三元Al-Cu-Mg合金相图与实验相图吻合很好,而且其对初始值的选取不敏感.     

Phase Equilibria in the Al-Co-Ni Alloy System

The phase equilibria in the Ni-Co rich region (<50 at.%Al) of the Al-Co-Ni system were studied experimentally for two isothermal sections at 1100 and 800 °C. Metallography, energy dispersive spectroscopy, hardness and x-ray diffraction were used for characterization and determination of γ, γ′ and β phases within the ternary system. Phase boundaries in the isothermal sections and a partial liquidus projection are modified compared to previously published work. Comparison is made to the isothermal sections computed using Thermo-Calc and the TCNI8 database. No definitive experimental evidence corroborating the predicted existence of a Nishizawa horn was obtained.     

Phase Equilibria in the Cu-Sn-Sb Ternary System

The phase equilibria in the Cu-Sn-Sb ternary system were investigated by means of electron-probe microanalysis and x-ray diffraction. Firstly, ternary solubilities of η-Cu₆Sn₅, δ-Cu₄₁Sn₁₁, Cu₁₁Sb₃, ε-Cu₃Sb and η-Cu₂Sb, were less than 7 at.% Sb or Sn at 400 °C. Besides, an re-stabilized ternary solubility, Cu₆(Sn,Sb)₅, was detected with a homogeneity range of Cu: 52.9-53.3 at.%, Sn: 28.4-30.9 at.%, and Sb: 15.8-18.7 at.%. Its origin was traced back to high-temperature stabilization of the binary η-Cu₆Sn₅ phase. Thirdly, the metastable phase, Cu₁₁Sb₃, was observed at 400 °C in the Cu-Sn-Sb ternary system; On raising the temperature to 500 °C, the ε-Cu₃Sn phase still retained a large solubility for Sb, at?~?16 at.%, while the ε-Cu₃Sb was replaced by β-Cu₃Sb with a dual-cornered large homogeneity range. Similarly, a ternary homogeneity range of Cu: 83.8-84.9 at.%, Sn: 2.6-6.2 at.%, and Sb: 9-12.5 at.%, was found and deduced to be the high temperature stabilization phase of γ-Cu₁₁(Sb,Sn)₂ at 500 °C.     

Phase Equilibria of the Nd-Fe-B Ternary System

Nd-Fe-B-based alloys as sintered Nd₂Fe₁₄B-typed permanent magnets have been studied extensively due to their excellent magnetic properties. In this work, the experimental information on the corresponding phase equilibria of the Nd-Fe-B ternary system in the published literature is reviewed first. The key Nd-Fe-B alloys annealed at 873 and 1073 K were then investigated experimentally to determine the phase equilibria of the system using x-ray diffraction technique and scanning electron microscope (SEM) with energy dispersive spectrometry (EDS). The ternary intermetallic compound, Nd₂Fe₁₄B with space group P4₂/mnm as Nd₂Fe₁₄B structure type, NdFe₄B₄ with space group Pccn as RE_l.11Fe₄B₄ structure type and Nd₅Fe₂B₆ with space group R \( \overline{3} \) m as Pr₅Co₂B₆ structure type were confirmed at 873 and 1073 K. The binary intermetallic compound Nd₅Fe₁₇ is stable at 873 K, while it was not found at 1073 K. The phase equilibria of the Nd-Fe-B ternary system consists of 14 single-phase regions, 28 two-phase regions and 16 three-phase regions at 873 K, while there are 8 single-phase regions, 14 two-phase regions and 7 three-phase regions at 1073 K except for the B-rich part.