Mixing Of Liquid Alloys Research Articles

Enthalpies of Mixing in Al−Ce−Co Liquid Alloys

AbstractThe enthalpies of mixing in liquid alloys of the ternary Al−Ce−Co system were determined along four sections (with a constant mole fraction ratio xCe/xCo=0.77/0.23 and xCe/xCo=0.35/0.65 up to xAl=0.2 at 1700 K; with xAl/xCo=0.76/0.24 up to xCe=0.3 and xAl/xCe=0.30/0.70 up to xCo=0.23 at 1823 K) via isoperibolic calorimetry. The enthalpies of mixing in the liquid Al−Ce−Co alloys are large exothermic values. A comparison of the experimentally obtained results for the enthalpies of mixing of liquid alloys and those calculated by the regular Redlich‐Kister‐Muggianu model, taking into account only the data for binary constituent systems, indicates the specific exothermic ‘ternary’ contribution to the energy of formation of Al−Ce−Co ternary alloys. Data on the partial enthalpy of mixing of cobalt at infinite dilution indicate the involvement of cerium 4 f‐electron in the process of alloy formation.

Enthalpies of mixing in ternary Ag–Eu–Sn liquid alloys

Abstract The enthalpies of mixing in liquid alloys of the ternary Ag–Eu–Sn system were determined over a wide range of concentrations by means of isoperibolic calorimetry in the temperature range from 1313 to 1373 K. The partial enthalpies of each component of the ternary system were measured along the following sections: Δ H ̄ Ag ${\Delta}{\bar{H}}_{\text{Ag}}$ along the section with x Eu /x Sn = 0.28/0.72 up to silver content of about x Ag = 0.2 at 1373 K; Δ H ̄ Sn ${\Delta}{\bar{H}}_{\text{Sn}}$ along three sections (x Ag/x Eu = 0.31/0.69, 0.50/0.50 and 0.70/0.30) up to x Sn = 0.35 at 1373 K; Δ H ̄ Eu ${\Delta}{\bar{H}}_{\text{Eu}}$ along the section x Ag/x Sn = 0.50/0.50 up to x Eu = 0.25 at 1313 K. The enthalpies of mixing in the liquid Ag–Eu–Sn alloys show exothermic effects, being more pronounced in the vicinity of the Eu–Sn binary constituent. The minimum value of the integral enthalpy of about −60 kJ mol−1 is observed in the composition region of the congruently melting Eu2Sn phase.

Enthalpies of mixing in ternary Al–Gd–Mn liquid alloys

Abstract The enthalpies of mixing in liquid alloys of the ternary Al–Gd–Mn system were determined over a wide range of compositions by means of isoperibolic calorimetry at 1650 K. The measurements of the partial enthalpies of components were performed along five sections: for the ΔH̅ Al (sections with x Gd/x Mn = 0.30/0.70 and 0.65/0.35 for x Al changed from 0 up to 0.30); for the ΔH̅ Gd (x Al/x Mn = 0.80/ 0.20 and 0.50/0.50 for x Gd changed from 0 up to 0.30); for the ΔH̅ Mn (x Al/x Gd = 0.29/0.71 for x Mn changed from 0 up to 0.26). The enthalpies of mixing in the ternary system were found to be exothermic and steadily increasing in absolute values from the Mn corner towards the Al–Gd constituent binary system, reaching the minimum value of approximately – 37 kJ · mol–1 in the vicinity of the Al0.6Gd0.4 composition, evidently related to the formation of stable Al2Gd phase.

Thermodynamic Properties of Melts of the Ternary System Ag–Al–Yb

Isoperibolic calorimetry is used to determine the enthalpies of mixing of liquid alloys of the Ag‒Al–Yb system along two radial sections with a constant ratio of atomic fractions of aluminum and silver: (1) xAg/xAl = 0.46/0.54 at 1271 ± 1 K and (2) xAg/xAl = 0.19/0.81 for 1454 ± 5 K up to xYb ∼ 0.2. It is found that melts of the studied system form with the release of a small amount of heat (ΔHmin = −29 kJ/mol), and the minimum ΔH accounts for the middle of the concentration triangle. Using the geometric and analytical Redlich–Kister models, calculations are made for ΔH triple system melts Ag–Al–Yb using similar data for double boundary subsystems.

Enthalpies of mixing in binary Cu–Eu and ternary Al–Cu–Eu liquid alloys

Abstract The enthalpies of mixing in liquid alloys of the binary Cu-Eu and ternary Al-Cu-Eu systems were determined over a wide range of compositions by means of isoperibolic calorimetry in the temperature range 1 300 - 1450 K. The enthalpies of mixing in the Cu-Eu system demonstrate small exothermic effects (ΔHmin = -4.1 ± 0.5 kJ · mol-1at xCu = 0.70). The measurements for the liquid ternary Al- Cu-Eu alloys were performed along five sections (xCu/ xEu = 0.70/0.30; 0.50/0.50 and 0.27/0.73 for xAl changed from 0 up to 0.30 and xAl/xEu = 0.20/0.80 and 0.47/0.53 for xCu changed from 0 up to 0.30). The enthalpies of mixing in the ternary system were found to be exothermic and increasing in absolute values from the Al corner towards the Al0.40Cu0.60-Al0.60Eu0.40section and from the constituent binary Cu-Eu system towards the same section. The minimum value of the integral enthalpy of mixing is expected in the vicinity of the Al0.6Eu0.4composition of the binary constituent Al-Eu system (about -23.00 kJ · mol-1).

Enthalpies of mixing in binary Cu–Eu and ternary Al–Cu–Eu liquid alloys

Abstract The enthalpies of mixing in liquid alloys of the binary Cu-Eu and ternary Al-Cu-Eu systems were determined over a wide range of compositions by means of isoperibolic calorimetry in the temperature range 1 300 - 1450 K. The enthalpies of mixing in the Cu-Eu system demonstrate small exothermic effects (ΔHmin = -4.1 ± 0.5 kJ · mol-1at xCu = 0.70). The measurements for the liquid ternary Al- Cu-Eu alloys were performed along five sections (xCu/ xEu = 0.70/0.30; 0.50/0.50 and 0.27/0.73 for xAl changed from 0 up to 0.30 and xAl/xEu = 0.20/0.80 and 0.47/0.53 for xCu changed from 0 up to 0.30). The enthalpies of mixing in the ternary system were found to be exothermic and increasing in absolute values from the Al corner towards the Al0.40Cu0.60-Al0.60Eu0.40section and from the constituent binary Cu-Eu system towards the same section. The minimum value of the integral enthalpy of mixing is expected in the vicinity of the Al0.6Eu0.4composition of the binary constituent Al-Eu system (about -23.00 kJ · mol-1).

Enthalpies of mixing in ternary Ce–Cu–Sb liquid alloys

Abstract The enthalpies of mixing in liquid alloys of the ternary Ce–Cu–Sb system were determined over a wide range of compositions by means of isoperibolic calorimetry at temperature 1300 K. Measurements were performed along five sections (x Cu/x Sb = 0.20/0.80; 0.40/0.60 and 0.60/0.40 for x Ce changed from 0 up to 0.35 and x Cu/x Ce = 0.20/0.80 and 0.60/0.40 for x Sb changed from 0 up to 0.25). The enthalpies of mixing in the ternary system were found to be exothermic and steadily increasing in absolute values from the binary constituent systems Ce–Cu and Cu–Sb towards the Ce–Sb boundary, reaching the minimum value of approximately –120 kJ · mol–1 in the vicinity of the phase CeSb.

Enthalpies of mixing in binary Mn–In and ternary Mn–In–Gd liquid alloys

AbstractThe enthalpies of mixing in liquid alloys of the binary Mn–In and ternary Mn–In–Gd systems were determined over a wide range of compositions by means of isoperibolic calorimetry in the temperature range 1 500 – 1 650 K. The enthalpies of mixing in the Mn–In system demonstrate endothermic effects (ΔHmax = 4.66 ± 0.38 kJ · mol−1 at xIn = 0.40). The enthalpies of mixing in the liquid ternary Mn–In–Gd alloys were determined along six sections (xMn/xIn = 0.22/0.78; 0.44/0.56; 0.65/0.35 and 0.83/0.17 for xGd changed from 0 up to 0.5 and xMn/xGd = 0.30/0.70; 0.60/0.40 for xIn changed from 0 up to 0.3). Enthalpies of mixing in the ternary system were found to be predominantly exothermic and steadily increasing in absolute values towards the Gd–In boundary binary system, reaching the maximum value in the vicinity of the phase GdIn.

Enthalpies of mixing in binary Fe–Sb, Ce–Fe and ternary Ce–Fe–Sb liquid alloys

Abstract The enthalpies of mixing in liquid alloys in the binary Fe–Sb, Ce–Fe and ternary Ce–Fe–Sb systems were determined over a wide range of composition by means of isoperibolic calorimetry in the temperature range 1600–1830 K. The minimum values of the integral enthalpy of mixing (ΔH min) were determined to be (−2.32 ± 0.22) kJ · mol−1 at x Sb = 0.5 in the Fe–Sb system, and (−0.97 ± 0.19) kJ · mol−1 at x Ce = 0.35 in the Ce–Fe system. The enthalpies of mixing in liquid ternary Ce–Fe–Sb alloys were found to increase smoothly from the binary boundary systems Ce–Fe and Fe–Sb towards the Ce–Sb system, reaching the minimum value of (−107.5 ± 3.6) kJ · mol−1 in the vicinity of the phase CeSb.

Transport and Surface Properties of Molten Cd-Zn Alloys

Simple statistical theory has been used to report the thermo-physical properties of mixing in liquid Cd-Zn alloys. The energetic of mixing in liquid alloys has been analyzed through the study of surface properties (surface tension, surface concentration) and transport properties (diffusivity, viscosity). Negative deviation from Raoultian behaviour has been observed in the computed mixing parameters (viscosity, surface tension) of the alloys. The computed results support a weak phase-separation tendency in molten Cd-Zn system.Journal of Institute of Science and Technology, 2014, 19(1): 14-18

Correlation Of Bulk And Surface Properties In Bi-Sn And Bi- In Liquid Alloys

We have used simple statistical model to report the energetic and its effect on the alloying behavior of Bi-Sn and Bi-In liquid alloys. The energetic of mixing in liquid alloys has been analyzed through the study of bulk and surface properties. In the bulk, we have studied thermodynamic properties, which include Gibb’s free energy of mixing, enthalpy of mixing and entropy of mixing. The surface behavior has been analyzed by computing surface concentration and surface tension of the alloys. For the microscopic structural investigation our study includes concentration-concentration fluctuation in long wavelength limit and Warren-Cowley short range order parameter, they have been discussed in term of the energetic of the bulk as well as that of the surface part. The computed results are in good agreement with experimental data and support a weak phase-separation tendency in molten Bi-Sn system and ordering behavior in Bi-In system. In both system, temperature dependent energy parameter takes important role to explain bulk and surface properties.

Theoretical assessment on segregating nature of liquid In–Tl alloys

Abstract We have used simple statistical theory to report the segregating nature of In–Tl liquid alloys. The energetic of mixing in liquid alloys has been analyzed through the study of surface properties, transport properties and various thermodynamic and microscopic functions. Positive deviation from Raoultian behavior has been observed in the computed mixing thermodynamic and microscopic parameters of the alloys. The computed results are in good agreement with experimental data and support a weak phase-separation tendency in molten In–Tl system. Surface properties have also been analyzed using two different approaches which reveal that with the addition of In atoms in In–Tl alloys, surface tension of the alloy increases and Tl atoms tend to segregate at the surface.

Enthalpies of mixing in liquid alloys of iron with the lanthanides

Abstract The enthalpies of mixing in binary liquid alloys of iron with the lanthanides (Pr, Nd, Gd, Tb, Dy and Lu) were determined at 1550–1950 K by means of isoperibolic calorimetry. They show exothermic effects (in the Fe–Pr system partially endothermic) which increase across the lanthanides row from the Fe–Pr system (ΔH min = −0.35 ± 0.10 kJ · mol−1 at x Pr = 0.22; ΔH max = 0.75 ± 0.24 kJ · mol−1 at x Pr = 0.76; T = 1829 K) to the Fe–Lu system (ΔH min = −11.58 ± 0.50 kJ · mol−1 at x Lu = 0.35; T = 1950 K).

Enthalpies of mixing of Al-Ni-La ternary alloys

Partial (for nickel) and integral enthalpies of mixing of liquid alloys of the Al-Ni-La ternary system of three radial sections with a constant ratio of molar fractions of aluminum and lanthanum xAl/xLa = 0.3/0.7 at 1770 ± 5 K and 0.5/0.5 and 0.8/0.2 at 1870 ± 5 K up to molar fractions of nickel in ternary alloys of approximately 0.5–0.6 are studied by means of high-temperature calorimetry in isoperibolic mode. It is found that the enthalpies of mixing of the melts are essentially exothermic values. Based on the energetics of alloy formation of this ternary system, it is concluded that the main contribution is made by interaction between the components of melts of the boundary Ni-Al binary system.

Mixing enthalpies in binary Ce-Sb and ternary Ce-Co-Sb liquid alloys

AbstractThe enthalpies of mixing in liquid alloys in the binary Ce-Sb and ternary Ce-Co-Sb systems were determined over a wide range of composition by means of isoperibolic calorimetry in the temperature range 1 600-1 723 K. The minimum value of the integral enthalpy of mixing (ΔHmin) in the Ce-Sb system was evaluated to be −123 kJ mol-1 at xCe = 0.55. The enthalpies of mixing in liquid ternary alloys were found to increase smoothly from the binary boundary systems Co-Ce and Co-Sb towards the Ce-Sb system reaching the value of approximately −123 kJ mol-1 in the vicinity of the phase CeSb.

Calorimetric study of Al–Ga system using Oelsen method

Abstract The results of calorimetric study of the Al–Ga system using Oelsen method are presented in this paper. Following thermodynamic parameters were obtained: activities, activity coefficients, partial and integral molar quantities at temperature of 727 °C, and compared with available literature data. Also, the energetic of mixing in liquid alloys has been analyzed through the study of concentration fluctuation in the long-wavelength limit.

A New Model for the Configurational Entropy of Mixing in Liquid Alloys Based on Short-Range Order

A new model has been developed to calculate the configurational entropy of mixing in liquid alloys involving consideration of chemical and topological short-range order. The entropy of mixing for an equiatomic random mixture was naturally reached by this model. The application of this model to both hypothetic and real binary liquid alloys demonstrated that the chemical short-range order always decreased the configurational entropy of mixing, whereas complicated behavior was found with the atomic size effect. The configurational entropy of mixing increased when the larger atoms entered into the matrix of the smaller atoms, whereas it decreased when the smaller atoms were mixed into the matrix of the larger atoms. The maximum of the configurational entropy of mixing was not located at the eutectic composition in these alloys.

Temperature–composition dependence of thermodynamic mixing functions of liquid alloys of copper with rare-earth metals

The composition and temperature dependences of thermodynamic functions of mixing in liquid alloys of copper with rare-earth metals and their variation in the series are considered. It is shown for majority of systems in the series that the most intensive interaction between components is observed in the composition range enriched with copper. The negative deviations of thermodynamic properties of mixing increase with decreasing temperature. The main features of the temperature–composition dependence are explained under the assumption that chemical short-range ordering like a chemical compound forms in the Cu–REM liquid alloys. The temperature–composition dependence of thermodynamic functions of mixing is described in the framework of the ideal associated solution model.

Critical evaluation and thermodynamic optimization of the Al–Ce, Al–Y, Al–Sc and Mg–Sc binary systems

Abstract New critical evaluations and optimizations of the Al–Ce, Al–Y, Al–Sc and Mg–Sc systems are presented. The Modified Quasichemical Model is used for the liquid phases which exhibit a high degree of short-range ordering. A number of solid solutions in the binary systems are modelled using the Compound Energy Formalism. All available and reliable experimental data such as enthalpies of mixing in liquid alloys, heats of formation of intermetallic phases, phase diagrams, etc. are reproduced within experimental error limits. It is shown that the Modified Quasichemical Model reproduces the partial enthalpy of mixing data in the liquid alloys better than the Bragg–Williams random mixing model which does not take short-range ordering into account.

Thermodynamics and surface properties of liquid Ga-X (X = Sn, Zn) alloys

The mixing behaviour of Ga-Sn and Ga-Zn segregating alloy systems has been investigated by the Quasi-Chemical Approximation (QCA) in the frame of the Quasi-Lattice Theory (QLT) combined with a statistical mechanical theory. Assuming the order energy parameters as temperature dependent, various thermodynamic quantities are calculated at different temperatures. Thermodynamic properties of both systems deviate positively from the Raoult’s law. The energetics of mixing in liquid alloys has been analysed through the study of surface properties (surface tension and surface composition) and microscopic functions (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter). Theoretical results are in a good agreement with the corresponding literature data and support a weak demixing tendency in Ga-Sn and Ga-Zn liquid alloys.