Mixing Enthalpies Of Liquid Alloys Research Articles

Thermodynamic Properties of the Glass-Forming Ternary (Fe, Co, Ni, Cu)–Ti–Zr Liquid Alloys I. Mixing Enthalpies of Liquid Alloys

Thermodynamic Properties of the Glass-Forming Ternary (Fe, Co, Ni, Cu)–Ti–Zr Liquid Alloys I. Mixing Enthalpies of Liquid Alloys

Interaction of Components in Glass-Forming Melts of Iron and Nickel with Titanium, Zirconium, and Hafnium I. Mixing Enthalpies of Liquid Alloys

Interaction of Components in Glass-Forming Melts of Iron and Nickel with Titanium, Zirconium, and Hafnium I. Mixing Enthalpies of Liquid Alloys

Enthalpy of mixing of liquid Cu–Fe–Hf alloys at 1 873 K

Abstract In the ternary Cu–Fe–Hf system, the mixing enthalpies of liquid alloys were investigated at 1873 K using a high-temperature isoperibolic calorimeter. The experiments were performed along the sections x Cu/x Fe = 3/1, 1/1 at x Hf = 0–0.47 and along the section x Cu/x Fe = 1/3 at x Hf = 0–0.13. The limiting partial enthalpies of mixing of undercooled liquid hafnium in liquid Cu–Fe alloys, Δ mix H ¯ Hf ∞ ${\Delta _{{\rm{mix}}}}\bar H_{{\rm{Hf}}}^\infty $ , are (−122 ± 9) kJ mol−1 (section x Cu/x Fe = 3/1), (−106 ± 9) kJ mol−1 (section x Cu/x Fe = 1/1), and (−105 ± 2) kJ mol−1 (section x Cu/x Fe = 1/3). In the investigated composition range, the integral mixing enthalpies are sign-changing. For the integral mixing enthalpy, an analytical expression was obtained by the least squares fit of the experimental results using the Redlich–Kister–Muggianu polynomial.

Mixing Enthalpies of Al–Co Melts

The partial mixing enthalpy of aluminum and the integral mixing enthalpies of liquid alloys in the binary Al–Co system are studied by high-temperature calorimetry at 1870 ± 5 K in the composition range 0 < x < 0.25. The energies of forming alloys of aluminum with metals in the second half of the 3d series are compared.

Thermodynamic Properties of Binary Al–Ce and Ce–Fe Alloys

The mixing enthalpies of liquid alloys in the binary systems Al–Ce (at 1540 K in the composition range 0.7 < x Ce < 1) and Ce–Fe (at 1830 K in the entire composition range) are determined by calorimetry. The thermodynamic properties of liquid alloys are calculated in the entire composition range using the model of ideal associated solutions. The thermodynamic activities of components show large negative deviations from the ideal solution for the Al–Ce melts and small ones for the Ce–Fe melts. The mixing enthalpies correspond to exothermic effects. The minimum values of the mixing enthalpies of liquid alloys are −45.8 ± 2.2 kJ/mol at x Ce = 0.37 for the Al–Ce system (1870 K) and −1.0 kJ/mol at x Ce = 0.36 for the Ce–Fe system (1830 K).

Formation enthalpies of Al–Fe–Zr–Nd system calculated by using geometric and Miedema's models

Formation enthalpy is important for the phase stability and amorphous forming ability of alloys. The formation enthalpies of Fe17RE2 (RE=Ce, Pr, Nd, Gd and Er) obtained by Miedema's theory are in good agreement with those of the experiments. The dependence of formation enthalpy on concentration of Al for intermetallic (AlxFe1−x)17Nd2 have been calculated by Miedema's theory and the geometric model. The solid solubility of Al in (AlxFe1−x)17Nd2 is coincident with the concentration dependence of formation enthalpy. The mixing enthalpies of liquid alloys and formation enthalpies of alloys for Al–Fe–Zr–Nd system have been predicted. The calculated mixing enthalpy indicates that the adding of Fe or Nd decreases monotonously the magnitude of enthalpy. The formation enthalpies of Al–Fe–Zr–Nd system indicate that the shape of the enthalpy contour map changes when the content of Al is less than 50.0at% and then it remains unchanged except the decrease of magnitude. The formation enthalpy of Al–Fe–Zr–Nd increases with the increase of Fe and/or Nd content. The negative formation enthalpy indicates that Al–Fe–Zr–Nd system has higher amorphous forming ability and wide amorphous forming range. The certain contents of Zr and/or Al are beneficial for the formation of Al–Fe–Zr–Nd intermetallics.

Mixing enthalpies of liquid nickel–gallium alloys

The partial mixing enthalpies of melt components in the Ni–Ga system are measured using hightemperature isoperibolic calorimetry at 1770 ± 5 K in a wide composition range. The partial mixing enthalpy of gallium in liquid nickel is –96 kJ/mol. for infinite dilution, while the same function of nickel in liquid gallium is –75 kJ/mol. The integral mixing enthalpy of liquid alloys in this system is calculated from partial enthalpies for the entire composition range (∆m H min = –32 kJ/mol. at xNi = = 0.5). The mixing enthalpies ∆m H of Ni–B (Al, Ga, In) binary alloys are compared. It is shown that the indicated systems are arranged in the Ni–In → Ni–Ga → Ni–B → Ni–Al series according to the increase in interaction energy of dissimilar components. The ∆m H min values of liquid Ni–B(Al, Ga, In) alloys are compared with the values of electrochemical and size factors.

Thermodynamic properties of Ni-Ga melts

The partial mixing enthalpies of the components (Δm\( \bar H \)i) of the Ni-Ga melts were measured using the high-temperature isoperibolic calorimetry at 1770 ± 5 K in wide concentration interval. The limiting partial mixing enthalpy of gallium in a liquid nickel (Δm\( \bar H \)Ga∞) is −95.5 ± 19.8 kJ mol−1, and similar function of nickel in liquid gallium (Δm\( \bar H \)Ni∞) is −74.5 ± 16.4 kJ mol−1. The integral mixing enthalpy of liquid alloys of this system was calculated from partial enthalpies for the whole concentration area (ΔmHmin = −32.1 ± 2.7 kJ mol−1 at xNi = 0.5). The ΔmH value of liquid nickel-gallium alloys independence of the temperature is confirmed. Enthalpies of formation of liquid (ΔmH) phases of Ni-Ga system were compared with ones for solid (ΔfH) phases of this system. An analysis of d-metals influence on formation energy of Ga-d-Me melts was made using the values of ΔfH for intermediate phases of these systems. The article was translated by the authors.

Thermodynamic properties of liquid alloys of the Ni-Hf system

By the method of calorimetry in isoperibolic conditions are determined integral and partial mixing enthalpies of liquid alloys of the Ni-Hf system at 1770 ± 5 K. Defined that liquid Ni-Hf alloys are formed with allocated large quantity of heat. The analysis of own and literary data has allowed to establish for mixing enthalpies of binary Ni-Hf liquid alloys dependence on temperature. With use of the Schroder equation are calculated the activities of studied alloys components from co-ordinates of liquidus line of the phase diagram of this system. Between calculated and experimentally established values of melts components activities of the Ni-Hf system is observed only qualitative consent. Are also calculated ΔG and ΔS of liquid Ni-Hf alloys.

Application du modèle de Hoch-Arpshofen: Estimation des fonctions thermodynamiques d'excès de systèmes métalliques à n constituants

The molar integral mixing enthalpy of liquid alloys [Bi–Cd–Ga–In–Pb–Sn–Zn] and the molar partial mixing enthalpies of the seven elements at the barycenter of this system have been determined by high-temperature calorimetry at 973 K. In order to use the Hoch-Arpshofen model, critical study of the thermodynamic properties and phase diagram of the 21 limiting binary systems have been compiled. The calorimetric results of the integral and partial enthalpies have been compared to the calculated results obtained with the Hoch-Arpshofen model. These two sets of values are in good agreement and so we may envisage to use this model for the estimation of the excess functions of formation of multicomponent alloys without strong interactions.

Enthalpy of Formation of Amorphous and Liquid Nickel-Zirconium Alloys

Formation enthalpies of amorphous and liquid Zr-Ni alloys were determined by liquid solution calorimetry. Formation enthalpy values of amorphous alloys are presented for the following compositions: Zr 0.75 Ni 0.25 , Zr 0.67 Ni 0.33 , Zr 0.65 Ni 0.35 , Zr 0.60 Ni 0.40 , Zr 0.35 Ni 0.65 , Zr 0.33 Ni 0.67 . Mixing enthalpies of liquid Zr-Ni alloys were measured at 1873K in the concentration range 0-60 at. % zirconium. The formation enthalpies of amorphous and liquid alloys have strong exothermic values. The minimum in formation enthalpies of amorphous and liquid alloys occur at practically the same composition. The experimental values of the amorphous and liquid alloys presented as approximating functions. Application of the ideal association solution model made it possible to derive the formation enthalpies of liquid alloys for the entire concentration range. The experimental data for the formation enthalpies of amorphous and liquid alloys and intermetallic compounds are very close to each other. Based on data for crystallisation enthalpies of amorphous alloys, formation enthalpies of the intermetallic compounds and the mixing enthalpy of liquid alloys, the excess specific heat of the undercooled liquid alloys was estimated. Conclusions about the thermodynamic reasons for easy glass formation in the investigated system were made.

High temperature calorimetric measurements on liquid PdLa and AuGd alloys

An improved method for the high temperature calorimetric determination of the mixing enthalpies of liquid alloys is presented. The method helps to avoid certain difficulties which are encountered in the process of treatment of calorimetric functions when the thermal equivalent of the calorimeter is unknown. The method was applied for measurement and calculation of the heats of mixing in PdLa and AuGd melts, which show a large exothermic effect of alloy formation owing to the very high electron affinity of palladium and gold.

Thermodynamische untersuchung der systeme GaSb-InSb, AlSb-GaSb und AlSb-InSb

The mixing enthalpies of liquid alloys of GaSb-InSb, AlSb-GaSb and AlSb-InSb quasi-binary systems have been determined with the aid of a high temperature calorimeter. The maximum deviations of the mixing enthalpy values of the ternary alloys from those linearly interpolated between the mixing enthalpies of the binary melts with the respective compounds are: δ ( ΔH) exp max = + 162 J mol −1 for GaSb-InSb, δ ( ΔH) exp max = − 417 J mol −1 for AlSb-GaSb, δ ( ΔH) exp max = + 562 J mol −1 for AlSb-InSb. For the AlSb-GaSb and AlSb-InSb melts, the concentration dependence of δ ( ΔH) is not in agreement with the values predicted by the regular solution model. The discrepancy originates from the misfit in the atomic structure of the melt as a result of differences in atomic radii and association effects.