Thermodynamic Assessments of the Bi-Tb and Bi-Y Systems

By using the calculation of phase diagrams (CALPHAD) method, the thermodynamic assessments of the Bi-Tb and Bi-Y systems were carried out based on the available experimental data including thermodynamic properties and phase equilibria. Gibbs free energies of the liquid, hcp, bcc, and rhombohedral phases in the Bi-Tb and Bi-Y systems were modeled by the substitutional solution model, and the intermetallic compounds (BiTb, Bi₃Tb₄, αBi₃Tb₅, βBi₃Tb₅, BiY, and Bi₃Y₅ phases) in these two binary systems were described by the sublattice model. An agreement between the present calculated results and experimental data was obtained.     

Thermodynamic Assessments of Al-In-Sb and Al-In-As Systems

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Thermodynamic Assessments of Ternary Ga-As-P,Ga-P-Sb,In-As-P and In-P-Sb Systems

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Thermodynamic Assessments of the Al2O3-Al4C3-AlN and Al4C3-AlN-SiC Systems

A thermodynamic dataset for the Al₂O₃-Al₄C₃-AlN system was reassessed and that of the Al₄C₃-AlN-SiC system was developed in present study for the first time based on available literature data using the CALPHAD approach. In the Al₂O₃-Al₄C₃-AlN system and its subsystems the liquid was described as single phase using the partially ionic liquid model $ ({\text{Al}}^{3 + } )_{P} ({\text{Va,AlC}}_{3/4} ,{\text{AlO}}_{3/2} , {\text{AlN}},{\text{O}}^{2 - } ,{\text{N,C}})_{Q} $ , which covers compositions from the metallic liquid to the oxide, carbide and nitride liquids. The compound energy formalism was used for modeling of the solid phases in both studied systems. Ternary phases ?? and ?? of the Al₄C₃-AlN-SiC system were treated as stoichiometric compounds. A four sublattice model was proposed in order to describe the ??-solid solution forming between the isostructural Al₅C₃N and Al₄SiC₄ binary phases. Using the derived datasets the isothermal sections at 1600, 2273 and 2373?K for the Al₂O₃-Al₄C₃-AlN system and at 2133?K for the Al₄C₃-AlN-SiC system were constructed. The calculated phase diagrams of both ternary systems were compared with the available experimental data.     

Thermodynamic Modeling of the Li-H and Ca-H Systems

The phase diagram and thermodynamic properties of the Li-H and Ca-H systems in the literature are critically reviewed. The Gibbs energy functions of individual phases in these two systems are modeled by the CALPHAD approach. The associate solution model and substitutional model are employed to represent the thermodynamic properties of the liquid phase in the Li-H and Ca-H systems, respectively. The available experimental data are well reproduced by the present modeling. With the obtained Gibbs energy functions, the phase relationships in the Li-H and Ca-H systems at high pressures are also predicted.     

Thermodynamic Description of the Al-Mo and Al-Fe-Mo Systems

The Al-Mo and Al-Fe-Mo systems were critically assessed using the CALPHAD technique. The solution phases (liquid, fcc and bcc) were described by a substitutional solution model. The non-stoichiometric compound AlMo₃ was described by a two-sublattice model (Al,Mo)(Al,Mo)₃ in the Al-Mo binary system and (Al,Fe,Mo)(Al,Fe,Mo)₃ in the Al-Fe-Mo ternary system. Other compounds Al₆₃Mo₃₇, Al₈Mo₃, Al₃Mo, Al₄Mo, Al₁₇Mo₄, Al₂₂Mo₅, Al₁₂Mo and Al₅Mo in the Al-Mo system were treated as stoichiometric compounds in the binary system and as line compounds Al _m (Fe,Mo) _n in the Al-Fe-Mo ternary system. The compounds μ and Fe₂Mo in the Fe-Mo system were treated as (Al,Fe)₇Fe₂(Fe,Mo)₄ and (Fe,Mo)₂(Al,Mo) in the Al-Fe-Mo system, respectively. Compounds Al₅Fe₄, Al₂Fe, Al₅Fe₂ and Al₁₃Fe₄ in the Al-Fe system were treated as (Al,Fe,Mo), Al₂(Fe,Mo), (Al,Fe)₅(Al,Fe,Mo)₂ and (Fe,Mo)_0.235Al_0.6275(Al,Va)_0.1375 in the Al-Fe-Mo system, respectively. Ternary compounds τ₁ and τ₂ were treated as Al₈(Al,Fe)Mo₃ and (Al,Fe,Mo)(Va)₃, respectively. A set of self-consistent thermodynamic parameters of the Al-Fe-Mo system was obtained.     

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.     

Ab-Initio Calculations and Thermodynamic Description of the Yb-Cd and Yb-Sn Systems

The phase diagrams of Yb-Cd and Yb-Sn systems were calculated by coupling the CALPHAD method and ab initio calculations. The enthalpies of formation of nine binary compounds (YbCd, αYbCd₂, Yb₂Sn, αYb₅Sn₃, βYb₅Sn₃, Yb₅Sn₄, YbSn, Yb₃Sn₅ and YbSn₃) were determined via ab initio density functional theory using the VASP code. Based on the available experimental data and the computed enthalpies of formation of the compounds, a thermodynamic assessment was carried out. The liquid phases and the γYb(bcc) and βYb(fcc) solid solutions were described by the Redlich–Kister polynomial model, while all the intermetallic compounds were treated as stoichiometric phases. A set of optimized model parameters were obtained for Yb-Cd and Yb-Sn systems. The calculated phase diagrams of these binary systems and their thermodynamic properties are presented and compared with the experimental data.     

Mo-RE二元合金相图的热力学数据库

利用CALPHAD方法,选择和建立合理的热力学模型,并结合相平衡及热力学性质的相关实验信息,对Mo-RE (RE: Ce, Pr, Nd, Sm, Eu, Tb, Ho, Er, Tm, Yb, Lu)各二元系相图进行了热力学优化与计算。其中,液相和端际固溶体相的Gibbs自由能采用亚正规溶体模型描述,气相的Gibbs自由能采用理想气体模型描述。计算结果与实验数据取得了良好的一致性,最终得到了一组自洽的合理描述Mo-RE二元系各相自由能的热力学参数,建立了Mo-RE (RE: Ce, Pr, Nd, Sm, Eu, Tb, Ho, Er, Tm, Yb, Lu)二元合金相图的热力学数据库。该热力学数据库可以提供相平衡及热力学性质等多种信息,为外推计算三元以及更多组元体系的相平衡提供理论基础,并为相关体系的合金设计及制备提供重要的理论指导。     

Thermodynamic Modeling of the La-B and La-Bi Systems Supported by First-Principles Calculations

Thermodynamic assessments of the La-B and La-Bi systems were carried out based on the available experimental data including thermodynamic properties and phase equilibria by means of the CALPHAD method. The enthalpies of formation at 0 K for the LaB₄, LaB₆, La₂Bi, La₅Bi₃, La₄Bi₃ and LaBi were computed via first-principles calculations. These enthalpies of formation were used “key experimental data” in the CALPHAD approach in order to obtain the thermodynamic parameters with sound physical meaning. The liquid phase has been modeled with both the substitutional solution model and associate model, and two sets of self-consistent thermodynamic parameters for the La-B and La-Bi systems were finally obtained. The calculated phase diagram and thermodynamic properties agree reasonably with the literature experimental data and the present first-principles calculations.     

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.