Huashan Liu

Thermodynamic reassessment of the AuIn binary system

Through CALPHAD method, the Auue5f8In binary system has been thermodynamically reassessed. The excess Gibbs energies of the solution phases, liquid, fcc, α1, and hcp were formulated with Redlich-Kister expression, while the γ and Ψ phases with narrow homogeneity ranges were described with sublattice models, and other intermetallic phases were treated as stoichiometric compounds. A set of self-consistent parameters has been obtained, which can reproduce most experimental data of thermodynamic properties and phase diagram of this binary system. Additionally, the standard formation enthalpies of all intermediate phases have also been calculated.

Thermodynamic optimization of Mg-Nd system

Based on the reported experimental data, the phase diagram of Mg-Nd binary system was optimized using the CALPHAD approach. Gibbs energies of the disordered BCC_A2 and ordered BCC_B2 phases were modeled with a single expression based on a 2-sublattice model. Liquid and terminal solutions, such as dHCP and HCP, were modeled as substitational solutions. Intermediate phases Mg2Nd, Mg3Nd and Mg41Nd5 were treated as stoichiometric compounds. The optimization was carried out in the Thermo-Calc package. A set of thermodynamic parameters is obtained. Calculated phase diagram, enthalpies of formation and Gibbs energies of formation are in reasonable agreement with the experimental data.

Thermodynamic Modeling of the Au-Bi-Sb Ternary System

Based on the available experimental information, the Au-Bi binary system has been thermodynamically assessed using the CALPHAD method. The solution phases, including liquid, fcc_A1, and rhombohedral_A7, were modeled as substitutional solutions, while the intermediate compound Au2Bi was described as a stoichiometric compound. Combined with the available thermodynamic parameters of the Au-Sb and Bi-Sb binary systems, a thermodynamic description of the Au-Bi-Sb ternary system has been developed to reproduce the reported phase equilibria. The liquidus projection and several vertical and isothermal sections of this ternary system have been calculated, which are in reasonable agreement with the reported experimental data.

Thermodynamic description of the Au–Al system

Abstract A thermodynamic assessment of the Au–Al system has been performed by using the CALPHAD method. The excess Gibbs energies of the solution phases were formulated with a Redlich – Kister expression, while the other intermetallic phases were described as stoichiometric compounds because of their limited composition ranges. Based on the experimental informations on the phase diagram and the thermodynamics, the thermodynamic parameters of all phases in this system have been optimized.

The melting behaviour of the lead-doped 2223 phase in Bi(Pb) SrCaCuO system

The melting behaviour of the lead-doped 2223 phase in the bismuth oxide system has been investigated by using DTA, XRD and EPMA techniques. The results indicated that 2223 phase began to decompose into liquid, (Ca, Sr)2CuO3 and (Sr, Ca)14Cu24O41 phases when fired at T ≥ 860 °C in air. The liquid composition is located on the line between 2212 and 2201 phases. When the liquid was cooled in air, 2212 and 2201 phases crystallized from it.

Optimization of the composition for synthesizing the high-Tc phase in Bi(Pb)SrCaCuO system

The optimal composition for synthesizing the high-Tc phase 2223 in the Pb-doped bismuth oxide system has been presented. It was shown by using DTA, SEM (EDAX) and XRD that a single 2223 phase could be fabricated when the sample of a Bi2.1 − xPbxSr1.9Ca2.05Cu3.0Oz, where x is between 0.2 and 0.3 (not including the loss of Pb), was sintered at 850–860 °C. It was also indicated that excessive Pb is more effective than excessive Cu in promoting the formation of 2223.

Melting of the 2212 phase in Bi(Pb)SrCaCuO system

The melting behavior of the 2212 phase in the Bi(Pb)SrCaCuO system has been investigated using DTA, XRD and EPMA. The effect of Pb and Ca on the melting of 2212 have also been discussed. The results indicate that the melting point of 2212 decreases monotonicaly with increasing Pb, however it reaches a peak value with the increase of Ca. 2212 melts incongruently into a liquid and (Sr,Ca)CuO2, and the crystals formed when the liquid is quenched in air vary with the starting concentrations of Pb and Ca.

Thermodynamic Optimization of the Na 2 O-B 2 O 3 Pseudo-Binary System

The Na2O-B2O3 system is thermodynamically optimized by means of the CALPHAD method. A two-sublattice ionic solution model, (Na+1)P(O−2,BO3−3,B4O7−2,B3O4.5)Q, has been used to describe the liquid phase. All the solid phases were treated as stoichiometric compounds. A set of thermodynamic parameters, which can reproduce most experimental data of both phase diagram and thermodynamic properties, was obtained. Comparisons between the calculated results and experimental data are presented.