Binary Boundary Systems Research Articles

Experimental study and modeling of the thermodynamic properties of Cu-Fe-Ni melts

The partial mixing enthalpy of nickel in ternary liquid Cu-Fe-Ni alloys is studied at 1873 K along sections characterized by ratios xCu: xFe = 3, 1, and 1/3 at xNi = 0–0.55. The investigations are undertaken using a high-temperature isoperibolic calorimeter. The temperature and composition dependence of the excess mixing Gibbs energy of liquid Cu-Fe-Ni alloys are described in terms of the Muggianu-Redlich-Kister model using the data obtained, the literature data on the activities of liquid alloy components, and the thermodynamic properties of melts of the boundary binary systems. This model is used to calculate isotherms of the thermodynamic properties of the liquid alloys over the entire composition range. The contribution of a ternary interaction to the integral mixing enthalpy of liquid Cu-Fe-Ni alloys is found to be mainly positive.

Reinvestigation of the isothermal section of the Ce–Co–Ge ternary system, at 700 °C

The solid state phase equilibria in the Ce–Co–Ge ternary system at 700 °C were investigated by means of X-ray diffraction and scanning electron microscope–energy dispersive X-ray spectroscopy. A total number of nine intermediate phases were characterized and the homogeneity ranges of the various ternary solid solutions of the binary boundary systems (Ce–Co, Ce–Ge and Co–Ge) were studied. The new ternary phase, CeCo 13− x Ge x (4 ≤ x ≤ 4.5) has been discovered. It crystallizes in the tetragonal space group I4 /mcm (no. 140), with the cell parameters a = 7.974(5) Å and c = 11.856(5) Å for x = 4. CeCo 9Ge 4 derives from the CeNi 8.5Si 4.5-type, but, with a perfect ordering of the atoms on the crystallographic sites. The phase diagram comprises seven extensions of binaries into the ternary system, eight stoichiometric ternary phases, CeCoGe, CeCo 2Ge 2, CeCoGe 3, Ce 2Co 3Ge 5, Ce 2CoGe 3, Ce 3CoGe 2, Ce 5CoGe 2 and Ce 5Co 4Ge 13 and two intermediate solid solutions, CeCo 1− x Ge 2 (0 ≤ x ≤ 0.24) and CeCo 13− x Ge x (4 ≤ x ≤ 4.5).

The thermodynamic characteristics of formation of alloys in the Ge-Ga-Mn and Si-Ni-Al systems

The enthalpies of mixing of ternary system melts were determined by high-temperature calorimetry under isoperibolic conditions. For the Ge-Ga-Mn system, measurements were taken at 1780 ± 5 K along five ray sections with constant ratios between the atomic fractions of germanium and gallium up to a ∼0.6 mole fraction of manganese; the xGe/xGa ratios were 0.8/0.2, 0.7/0.3, 0.5/0.5, 0.3/0.7, and 0.15/0.85. For the Si-Ni-Al system, measurements were taken at 1770 ± 5 K along five ray sections with constant ratios between the atomic fractions of silicon and nickel up to a ∼0.6 mole fraction of aluminum; the xSi/xNi fratios were 0.85/0.15, 0.7/0.3, 0.5/0.5, 0.3/0.7, and 0.15/0.85. The formation of melts in these systems was found to be exothermic over the composition range studied. The integral enthalpies of melt formation were maximum along the xGe/xGa = 0.8/0.2 section in the Ge-Ga-Mn system (−18.8 ± 3.3 kJ/mol) and along the xSi/xNi = 0.5/0.5 section in the Si-Ni-Al system (−67.8 ± 3.4 kJ/mol). An analysis of the isolines of the integral enthalpies of mixing led us to conclude that the Ge-Mn and Ga-Mn binary systems had the strongest influence on the thermodynamic characteristics of melt formation in the Ge-Ga-Mn system, the predominant influence being that of the Ge-Mn binary system. An analysis of the energy characteristics of melt formation in the Si-Ni-Al ternary system showed that the major contribution was made by the interaction of components in the Si-Ni and Ni-Al boundary binary systems, the influence of the Si-Ni system being stronger.

Application of Wilson’s method to the calculation of thermodynamic properties of liquid ternary metallic systems from the data on boundary binary systems

The possibility of applying Wilson’s polynomial to the description of concentration dependences of thermodynamic functions in binary liquid metallic systems and to the calculation of thermodynamic properties of ternary systems from the data on boundary binary systems was considered.

Isothermal section at 900 °C of the Ce–Fe–Si ternary system

The phase equilibria in the ternary Ce–Fe–Si system at 900 °C was investigated by means of X-ray diffraction and Scanning Electron Microscope–Energy Dispersive X-ray Spectroscopy (SEM–EDS). A total number of six ternary compounds were characterized and the homogeneity ranges of the various ternary solid solutions of the binary boundary systems (Ce–Fe, Ce–Si and Fe–Si) were studied. A new ternary phase, CeFe 13− y Si y (3.5 < y < 5) has been found. It crystallizes in the tetragonal space group I4/ mcm (no. 140), with the cell parameters a = 7.892(1) Å and c = 11.666(1) Å for y = 4. Its crystal structure derives from the Ce 2Ni 17Si 9-type, with fully ordered atoms on the crystallographic sites for CeFe 9Si 4. The phase diagram comprises four extensions of binaries into the ternary system, Ce 2Fe 17− x Si x (0 < x < 3), CeFe 2− x Si x (0 < x < 0.15), CeFe x Si 2−α1− x (0 < x < 0.1) and CeFe x Si 2−α2− x (0 < x < 0.14), four ternary compounds CeFeSi 2, CeFeSi, CeFe 2Si 2 and Ce 5Fe 2Si 8, and two intermediate solid solutions CeFe 13− x Si x (2.4 < x < 2.6) and CeFe 13− y Si y (3.5 < y < 5).

Thermodynamic properties of liquid Cu-Ni-Co-Fe alloys

Data on boundary binary systems in conjunction with geometric models and the Redlich-Kister method were used to calculate the integral thermodynamic characteristics and the activities of the components for liquid Cu-Ni-Co-Fe alloys at 1600°C.

Electrical conductivity of solutions of the LiIO3-HIO3-H2O system

The electrical conductivity of aqueous LiIO3 solutions and solutions of the LiIO3-HIO3-H2O system is measured over a wide range of compositions at 25, 50, and 75°C. Isothermal surfaces of electrical conductivity are mapped, and the activation energies of conductivity are calculated. The conductivity isotherms in the LiIO3-H2O and HIO3-H2O boundary binary systems and in mixed solutions along sections with fixed electrolyte ratios each have a maximum as a function of electrolyte concentration. It is assumed that structure reorganization occurs in solutions in the concentration range corresponding to the peak conductivity. Proton migration features in the solutions in question are considered.

Activity of iron and nickel in the copper-rich region of compositions of the copper-iron-nickel system in the liquid state

Activities of iron and nickel in the copper-rich part of the Cu-Fe-Ni system in the liquid state at 1350°C were calculated using model concepts from data on the boundary binary systems.

Activity of Components in Liquid Alloys of the Iron-Cobalt-Nickel System

Data on the thermodynamic properties of boundary binary systems were used to calculate the activities of components in liquid alloys of the iron-cobalt-nickel ternary system at a temperature of 1600°C.

Ternary Rare‐Earth Aluminum Systems with Copper: A Review and a Contribution to Their Assessment

AbstractFor Abstract see ChemInform Abstract in Full Text.

Ternary rare-earth aluminum systems with copper: A review and a contribution to their assessment

Constitutional data of the R-Cu-Al systems, with R = rare earth, are summarized and discussed. Crystal structures of the phases formed in the binary boundary systems and in the ternary systems are assessed, and the phase equilibria observed in the reported ternary systems are reviewed with special attention given to the isothermal and polythermal sections of the phase diagrams. Some regularities observed in the trends of the constitutional properties of the ternary R-Cu-Al alloys are briefly described.

Thermodynamic Properties of Liquid Alloys of the System Iron-Nickel-Cobalt

The integral molar excess Gibbs energy and the enthalpy of mixing of liquid alloys of the ternary system iron-nickel-cobalt at 1600°C were calculated by various methods from data on the boundary binary systems. The data for the boundary binary systems are analyzed in detail.

Thermodynamics of liquid aluminium–copper–silicon alloys

In this paper, thermodynamic properties of liquid Al–Cu–Si alloys were studied by electromotive force method with liquid electrolyte at 920–1250 K and by high-temperature isoperibolic calorimetry at 1750±5 K. The integral enthalpy of mixing in ternary Al–Cu–Si melts was estimated by Bonnier model for definition of boundary binary systems contribution to ternary alloys thermodynamics. The satisfactory agreement between experimental and estimated data demonstrates that thermodynamic properties of ternary liquid alloys are mainly defined by thermodynamic behaviour of boundary binary systems. Analysis of concentration and thermal dependencies of thermodynamic functions of mixing in liquid Al–Cu–Si alloys has been performed. It has been established that increasing of temperature results in decreasing of the integral enthalpy of mixing. This fact is probably associated with contribution of silicon clusters into ternary alloys thermodynamics.

Thermodynamics of liquid aluminium–copper–silicon alloys

In this paper, thermodynamic properties of liquid Al–Cu–Si alloys were studied by electromotive force method with liquid electrolyte at 920–1250 K and by high-temperature isoperibolic calorimetry at 1750±5 K. The integral enthalpy of mixing in ternary Al–Cu–Si melts was estimated by Bonnier model for definition of boundary binary systems contribution to ternary alloys thermodynamics. The satisfactory agreement between experimental and estimated data demonstrates that thermodynamic properties of ternary liquid alloys are mainly defined by thermodynamic behaviour of boundary binary systems. Analysis of concentration and thermal dependencies of thermodynamic functions of mixing in liquid Al–Cu–Si alloys has been performed. It has been established that increasing of temperature results in decreasing of the integral enthalpy of mixing. This fact is probably associated with contribution of silicon clusters into ternary alloys thermodynamics.

Ternary rare earth germanium systems with Cu and Ag—A review and a contribution to their assessment

Constitutional data of the R-(Ag, Cu)-Ge systems, with R=rare earth, are summarized and discussed. Crystal structures of the phases formed in the binary boundary systems and in the ternary systems are assessed, and the phase equilibria observed in the reported ternary systems are reviewed with special attention to the isothermal sections (generally at 400 or 600 °C) of the phase diagrams. Some regularities observed in the trends of the constitutional properties of the ternary R-(Ag, Cu)-Ge alloys are briefly described.

Phase Equilibria in the Hafnia–Yttria–Lanthana System

The HfO2–Y2O3–La2O3 system was studied in the wide range of temperatures (1250°–2800°C) and concentrations by methods of X‐ray analysis at 20°C, petrography, differential thermal analysis in helium at temperatures to 2500°C, thermal analysis in air using a solar furnace at temperatures to 3000°C, and electron microprobe X‐ray analysis. The complete phase diagram was constructed. The liquidus and solidus projections, crystallization paths for the alloys, isothermal (1250°, 1600°, and 1900°C) and polythermal sections are presented. The structure of the boundary binary systems defines the phase equilibria in the ternary system. No ternary compounds were found. Ternary solid‐solution regions were determined based on constituent oxides and intermediate phases.

Phase Equilibrium in the Fluorapatite–Anorthite–Diopside System

The binary systems Ca5[PO4]3F–CaAl2Si2O8 and Ca5[PO4]3F–CaMgSi2O6 have been investigated, via annealing and quenching in the experimental method, direct observation of the melting behavior of the samples, X‐ray diffraction analysis, petrography, and transmission electron microscopy. Phase equilibrium in the ternary system Ca5[PO4]3F–CaAl2Si2O8–CaMgSi2O6 was determined by combining information from the structure of the binary boundary systems and additional experimental data that were obtained from ternary compositions. The glass‐formation region of the fluorapatite–anorthite–diopside system was studied, and the glass compositions for the development of glass‐ceramics for technical and medical applications were identified.

Mass-spectrometric determination of the thermodynamic mixing behavior of liquid ternary Fe–Ni–Cr alloys

Thermodynamic investigations on liquid ternary Fe–Ni–Cr alloys have been performed by means of the computer-aided Knudsen cell mass spectrometry. Ternary thermodynamically adapted power (TAP) series are used for the algebraic representation of the thermodynamic excess properties. At 1950 K, the molar excess Gibbs energy G E is negative in the predominant part of Gibbs triangle (minimum value: −2980 J/mol at x Ni=0.55, x Cr=0.45), and positive only near the liquid binary Cr–Fe alloys (maximum value: 940 J/mol at x Cr=0.375, x Fe=0.625). The molar heat of mixing H E is exothermic for nearly all Fe–Ni–Cr melts (minimum value: −4770 J/mol at x Fe=0.38, x Ni=0.62). Only the Cr-richest ternary melts near the Ni–Cr binary alloys are slight endothermic (maximum value: 80 J/mol at x Ni=0.125, x Cr=0.87). The molar excess entropy S E is slight negative for ternary Fe–Ni–Cr melts near the two binary boundary systems Fe–Ni and Cr–Fe with a minimum S E value of −1.27 J/mol K at x Cr=0.40 and x Fe=0.60, and slight positive at the side of binary Ni–Cr melts (maximum S E value: 1.35 J/mol K at x Ni=0.50, x Cr=0.50). The Fe-activities of liquid ternary Fe–Ni–Cr alloys as determined, in this work, show slight negative deviations from the ideal behavior in the range of composition below the section of constant mole fraction x Cr/ x Ni=1, and slight positive deviations from Raoult's law above this section line. The Ni-activities of all ternary Fe–Ni–Cr melts show negative deviation from the ideal behavior. The Cr-activities show slight positive deviations from Raoult's law in the range of composition on the left-hand side of the section of constant mole fraction x Ni/ x Fe=1, and slight negative deviations from the ideal behavior on the right-hand side of this section line. The results of this work can be used successfully for phase-diagram calculations.

A thermodynamic analysis of cermet sintering of TiN-Ni powder mixtures

The Ti-Ni-N phase diagram has been thermodynamically assessed, and a consistent set of thermodynamic functions has been developed. An extended ternary solubility of nitrogen in Ti2Ni and the ternary interaction in liquid phase have been modeled. The solid ternary solution phases were extrapolated from the thermodynamic descriptions of the binary boundary systems. The experimental phase equilibria at 1100 and 900 °C have been well reproduced. The thermodynamic description of the Ti-Ni-N system has been applied to study the conditions for the formation of nitride inclusion in nickel alloys containing titanium, the nitridation of Ni-Ti alloys, and the denitrification, phase formation, and vaporization during the sintering of the TiN-Ni mixed powder compacts.

Computation of phase equilibria in the Fe–Ni–Cr system based upon mass spectrometric investigations

Phase diagram calculations require only the differences between the chemical potentials of the involved phases. This makes it possible to use even artificial thermodynamic parameter sets which then have to be corrected by means of additional terms. It is demonstrated that mass spectrometric investigations yield a simpler, but more effective algebraic description of the thermodynamic ternary mixing behavior than the results of previous phase diagram assessments: mass spectrometric measurements in the liquid phase, and in the restricted field of fcc-phase in the system Fe–Ni–Cr together with the algebraic descriptions of the three binary boundary systems Fe–Ni, Ni–Cr, and Cr–Fe as reported in previous works make it possible to compute ternary phase equilibria in the system Fe–Ni–Cr, showing better agreement with the experimental phase equilibria data than the assessments as reported by Kundrat and Elliot, Hillert and Qiu, and Lee. Additional advantage of the mass spectrometric determined molar Gibbs energy is that the description of the magnetic contributions Z α,mag k ( T, x α ) has been merely reduced to the expressions of the pure species.