Experimental Investigation and Thermodynamic Description of the Cu-Zr System

The Cu-Zr binary system is re-investigated via experiment and thermodynamic modeling. Four alloys were prepared by arc melting in order to check the controversial phase equilibria reported in the literature. Both as-cast and annealed alloys were examined by optical microscopy, x-ray diffraction and electron probe microanalysis, and the phase transformation temperatures were measured by differential scanning calorimetry. The intermetallic compounds, Cu₂₄Zr₁₃, Cu₂Zr and Cu₅Zr₈, were demonstrated to be not the stable phases. Based on the literature information and present experimental data, the Cu-Zr system was critically evaluated by means of CALculation of PHAse Diagram approach. A set of self-consistent thermodynamic parameters was obtained, and the calculated phase diagram and thermodynamic properties are in a satisfactory agreement with the experimental data.     

Experimental Investigation and Thermodynamic Assessment of the Hf-Mn System

The Hf-Mn binary system was investigated via experiment and thermodynamic assessment. Six alloys, which were prepared by arc melting the elements, were annealed at 1223 K for 240 h or at 923 K for 408 h, followed by analysis using x-ray diffraction, optical microscopy, scanning electron microscopy, and electron probe microanalysis. The homogeneity range of HfMn₂ was determined to be from 66.4 to 73.5 at.% Mn at 1223 K and from 65.3 to 73.0 at.% Mn at 923 K, while that for HfMn was measured to be very limited (48.4-49.0 at.% Mn at 1223 K). The invariant equilibrium of βHf ↔ αHf + HfMn, which was previously proposed to occur at 1123 K, was not observed according to the present differential thermal analysis. The thermodynamic optimization for the Hf-Mn system is then conducted by taking into account the reliable experimental data from the literature and the present work. The calculation using the obtained parameters can reproduce most of the experimental phase diagram data and thermodynamic properties.     

Experimental Investigation and Thermodynamic Calculation of the Co-Cr-Mo System

The isothermal section of the Co-Cr-Mo system at 1200 K has been investigated experimentally using scanning electron microscopy coupled with energy dispersive x-ray spectroscopy and x-ray diffraction. Six three-phase regions exist in the 1200 K isothermal section. The experimental results indicated that the maximum solubility of Cr in Co-Mo binary compounds Co₃Mo and μ at 1200 K is 5.2 and 23.6 at.%, respectively, and that of Mo in Co-Cr binary compound σ is 39.6 at.%. Based on the literature data of the thermodynamic assessment of Co-Mo, Co-Cr, Cr-Mo binary systems and experimental results of the ternary system, the thermodynamic calculation for Co-Cr-Mo system was carried out by means of CALPHAD technique. The computational results and the experimental data are self-consistent reasonably.     

Experimental Investigation and Thermodynamic Calculation of the B-Co-Zn Ternary System

The 450 °C isothermal section of the B-Co-Zn ternary system has been determined using scanning electron microscopy, electron probe microanalysis and x-ray diffraction. Seven three-phase regions exist in the 450 °C isothermal section, and no ternary compound is found. The experimental results indicate that the maximum solubility of B in β₁, γ, γ₁ and γ₂ is 0.31, 2.54, 0.52 and 2.51 at.%, respectively. The solubility of Zn in Co₂B and CoB is not greater than 0.6 at.%. On the basis of the literature data of the thermodynamic assessment of Co-B, Co-Zn binary systems and B-Zn system obtained in the present work, the phase diagram calculation for B-Co-Zn ternary system was carried out by means of CALPHAD method. The calculated results and the experimental data are in good agreement.     

Thermodynamic Description of the Ti-Al-O System Based on Experimental Data

Phase equilibria of the TiO₂-Al₂O₃ system were investigated experimentally using XRD, SEM/EDX and DTA methods. Temperature stability limits of the aluminum titanate (Al₂TiO₅) were detected. The thermodynamic parameters of the liquid phase as well as solid solution phases were assessed by CALPHAD approach using obtained experimental results. The thermodynamic data for the Ti-Al, Al-O and Ti-O systems and available experimental data for the Ti-Al-O system were critically evaluated and optimized to develop database of the Ti-Al-O system.     

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 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.     

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 Researches Regarding the Thermodynamic Activities in the Binary Pb-Sb Alloy System

We have determined the thermodynamic activity of Pb and Sb in the Pb-Sb binary system. For the experiments, we used a galvanic cell in which the measuring electrode was made of Pb-Sb alloys with different chemical compositions. The reference electrode was manufactured from pure lead, and a mixture of salts (35% KCl, 17% NaCl and 48% PbCl₂) was used as an electrolyte, which had a melting temperature of 399 °C (672 K). Tungsten wires were used for the contact conductors of the electrodes, and platinum wires were used for the electrical contacts between the measurement instrument and the contact conductors. The variations of activity coefficients depending on its atomic fraction were calculated for the Pb and Sb in the Pb-Sb binary alloy system. The experimental measurements were performed at a temperature of 650 °C (923 K). The obtained data are reliable and consistent, and now, based on these, thermodynamic functions can be obtained that can help the scientific community to correctly describe the behavior of the Pb-Sb binary alloy system.     

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

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