Papers by Keyword: CALPHAD

Abstract: Only one intermediate compound Ba₃Lu₄O₉was identified at 1373, 1573 and 1773K in the BaO-Lu₂O₃system in present work.Based on the available experimental phase diagram and relevant thermodynamic data, BaO-Lu₂O₃ binary system was optimized and calculated by using CALPHAD method. The Gibbs free energy of high temperature solution was described by an ionic two-sublattice model as (Ba²⁺,Lu³⁺)_P(O^2-)_Q. The calculated phase diagram, Gibbs energy of intermediate phase Ba₃Lu₄O₉and Gibbs energy of mixingagreewell with experimental resultswithin error limits. The study will offer theoretical basis for further research of the phosphor matrix system of BaO-Lu₂O₃-SiO₂, but also provide new idea for the phase diagram and thermodynamic research on related metallurgical slags, refractories, high-temperature superconductivity material systems.

Abstract: Sc-based alloys have been used as aero-structures materials, and Sc addition on wrought alloys has positive effects on weldability and welding properties. Phase diagrams play an effective role during the development of new type of alloy with good properties. Therefore, to establish the thermodynamic database of Sc-X binary systems is important and necessary.In the present work, the thermodynamic assessments of Sc-X (Ag, B, Cr, Er, Gd, Mo, Th, W, Y, Zr) binary systems was carried out by using CALPHAD (Calculation of Phase Diagrams) method based on the experimental data including thermodynamic properties and phase equilibria. The Gibbs free energies of the solution phases were described by the sub-regular solution model with the Redlich-Kister equation, and those of the intermetallic compounds were described by the sub-lattice model. A set of self-consistent thermodynamic parameters were derived for describing the Gibbs free energies of each solution phase and intermetallic compound. The calculated phase diagrams and thermodynamic properties are in good agreement with experimental data. The thermodynamic database of the Sc-X (Al, Ag, B, Ca, Co, Cr, Cu, Er, Fe, Ga, Gd, Ge, La, Li, Mg, Mn, Mo, Ni, Pb, Pd, Ru, Sn, Th, W, Y, Zn, Zr) binary systems have been developed, which can provide much important thermodynamic information for multicomponent Al-Sc based alloys.

Abstract: In this work, eleven Mn-La alloys were investigated experimentally by means of thermal analysis. The temperatures of the invariant reactions in the Mn-La binary system were determined. To confirm whether the liquid miscibility gap exists in the Mn-La system, one key alloy (Mn₇₂La₂₈) was prepared and then checked by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). Microstructure observation and composition analysis indicated the nonexistence of the liquid miscibility gap. Based on the experimental results obtained in the present work and the critical review of the available experimental data in the published literature, a set of self-consistent thermodynamic parameters for the Mn-La system was obtained using the CALPHAD method by thermodynamic optimization of the selected experimental data.

Abstract: As the key sub-binary systems in the rare-earth (RE) permanent magnetic materials with excellent magnetic properties (e.g. Nd-Fe-B, Sm-Fe-N magnets), the Fe-RE binary systems were investigated widely due to the industrial applications of permanent magnets. In this work, the experimental data of phase equilibria and thermodynamic properties of the Fe-RE binary systems (RE=La, Ce, Pr, Nd) in the published literature are reviewed firstly. Based on available phase equilibria data and thermodynamic data, the Fe-RE binary systems are assessed thermodynamically using the CALPHAD method. As a result, further experimental information and thermodynamic calculations will be both required in order to develop thermodynamic database of the RE-Fe-B ternary systems, which is very useful to study the relations between alloy composition, microstructure and magnetic properties of novel Nd-Fe-B-based permanent magnets.

Abstract: The phase equilibria of new-type Co-based superalloys which include the system of Co-Al-W were studied by CALPHAD method. It was shown that γ+γ' two-phase regions were existed in the calculated phase diagrams. The compositions of new-type Co-based superalloys which can obtain γ+γ' microstructures were predicted due to the calculated phase diagram. The mole fractions of the constituent phases of Co-Al-W-Ni-Cr alloys were calculated. The temperature of γ' phase began to precipitate at about 1050°C.

Abstract: The SiO₂-ZrO₂ binary system has been thermodynamically assessed with CALPHAD approach. The substitutional solution model is adopted for liquid. A set of self-consistent parameters capable of reproducing the corresponding experimental phase diagram data and liquidus immiscibility data has been obtained.

Abstract: The B₂O₃-SiO₂ binary system has been thermodynamically reassessed with CALPHAD approach. The substitutional solution model is adopted for liquid. A set of self-consistent parameters capable of reproducing the corresponding experimental phase diagram data and subliquidus immiscibility data has been obtained.

Abstract: Abstract: The atomic mobilities for impurity diffusion of Al, Au, Co, Cu, Mn, Mo, Nb, Ni, Pt, Sn and Zn in fcc Fe have been critically assessed based on the experimental diffusion coefficient data available in the literature. The impurity diffusion coefficients calculated from the atomic mobilities agree reasonably well with the reliable experimental data. This work provides a helpful guidance for the establishment of a general Fe-based mobility database to design new Fe-based alloys for practical purposes.

Abstract: The molar volume of fcc phase in the Ni-Cr-Mo system has been evaluated by means of the CALPHAD approach based on experimental data from the literature. The molar volumes of the non-stable fcc Cr and Mo were determined by extrapolating volume data from several stable solid solutions combined with the first-principles calculation results. A set of parameters has been obtained and can give a reasonable description of most experimental data on molar volume.

Abstract: The diffusion-couple experiments have been performed at 1273 K and 1423 K in order to verify and bias the controversial interdiffusion data in the literature. In the meantime, the literature data on the lattice parameter have been assessed to obtain the molar volume of fcc Fe-Co phase, which was in turn fed into the Sauer-Freise equation to retrieve the interdiffusion coefficients from the EPMA (Electron Probe Micro-Analysis) measured diffusion profiles. The reliable experimental data on the diffusion coefficients for fcc Fe-Co phase have finally been used to assess the atomic mobility. A general agreement has been reached between the calculated and experimentally measured data.