Binary Subsystems Research Articles

Thermodiffusion in Ternary Mixtures of Water/Ethanol/Triethylene Glycol: First Report on the DCMIX3-Experiments Performed on the International Space Station

We report on thermodiffusion experiments conducted on the International Space Station ISS during fall 2016. These experiments are part of the DCMIX (Diffusion and thermodiffusion Coefficients Measurements in ternary Mixtures) project, which aims at establishing a reliable data base of non-isothermal transport coefficients for selected ternary liquid mixtures. The third campaign, DCMIX3, focuses on aqueous systems with water/ethanol/triethylene glycol as an example, where sign changes of the Soret coefficient have already been reported for certain binary subsystems. Investigations have been carried out with the SODI (Selectable Optical Diagnostics Instrument) instrument, a Mach-Zehnder interferometer set up inside the Microgravity Science Glovebox in the Destiny Module of the ISS. Concentration changes within the liquids have been monitored in response to an external temperature gradient using phase-stepping interferometry. The complete data set has been made available in spring 2017. Due to additionally available measurement time, it was possible to collect a complete data set at 30∘C and an almost complete data set at 25∘C, which significantly exceeds the originally envisaged measurements at a single temperature only. All samples could be measured successfully. The SODI instrument and the DCMIX experiments have proven reliable and robust, allowing to extract meaningful data even in case of unforeseen laser instabilities. First assessments of the data quality have revealed six out of 31 runs with some problems in image contrast and/or phase step stability that will require more sophisticated algorithms. This publication documents all relevant parameters of the conducted experiments and also events that might have an influence on the final results. The compiled information is intended to serve as a starting point for all following data evaluations.

Water Activity and Solubility Measurements and Model Simulation of the CsCl–MgCl2–H2O Ternary System at 323.15 K

Water activities in the ternary system CsCl–MgCl2–H2O and its sub-binary systems at 323.15 K were elaborately measured by an isopiestic method. Moreover, the solubility of the CsCl–MgCl2–H2O system at 323.15 K was also measured by the flow-cloud-point method. A Pitzer model was used to predict the measured water activity and solubility data. The binary parameters for the CsCl–H2O system at 323.15 K were obtained by fitting the measured water activities for this binary system. The calculated water activity and solubility isotherms for the CsCl–MgCl2–H2O system at 323.15 K, with binary parameters only, deviated from the experimental values. This means that it is insufficient with binary parameters only to predict the water activity and calculate the solubility isotherms of the CsCl–MgCl2–H2O system at 323.15 K. The calculated solubility isotherms with both binary and mixing parameters, obtained by fitting the measured water activity, also deviated from experimental values. A new set of reasonable ternary pa...

Thermodynamics of soluble fission products cesium and iodine in the Molten Salt Reactor

The present study describes the full thermodynamic assessment of the Li,Cs,Th//F,I system. The existing database for the relevant fluoride salts considered as fuel for the Molten Salt Reactor (MSR) has been extended with two key fission products, cesium and iodine. A complete evaluation of all the common-ion binary and ternary sub-systems of the LiF-ThF4-CsF-LiI-ThI4-CsI system has been performed and the optimized parameters are presented in this work. New equilibrium data have been measured using Differential Scanning Calorimetry and were used to assess the reciprocal ternary systems and confirm the extrapolated phase diagrams. The developed database significantly contributes to the understanding of the behaviour of cesium and iodine in the MSR, which strongly depends on their concentration and chemical form. Cesium bonded with fluorine is well retained in the fuel mixture while in the form of CsI the solubility of these elements is very limited. Finally, the influence of CsI and CsF on the physico-chemical properties of the fuel mixture was calculated as function of composition.

Modeling of acid gases solubility in ionic liquid [BMIM][MeSO4] using CPA EoS

ABSTRACTThis work follows the thermodynamically modeling procedure to correlate the solubility of pure CO2 and H2S in [BMIM][MeSO4]. Moreover, solubility of acid gases mixture was predicted. The bubble point pressure calculation method was applied in which CPA EoS is responsible for fugacity coefficients calculation of the components. The CPA EoS combines SRK and Wertheim's association term to handle non-ideal behavior of the polar and associating components.The AADs% of H2S+IL and CO2+IL binary subsystems were calculated as 18.4 and 17.36 respectively. Moreover, AADs% equal to 27.26 and 6.74 were obtained for predicted partial pressures of CO2 and H2S, respectively.

Thermodynamic assessment of oxide system In2O3-SnO2-ZnO

The In2O3-SnO2-ZnO system is of special interest for applications as transparent conducting oxides and also transparent semiconductors. In the present work, a thermodynamic assessment for this system is discussed using all available experimental data on phase equilibria and thermodynamic properties. All sub-systems including elemental combinations were considered in order to generate a self-consistent Gibbs energy dataset for further calculation and prediction of thermodynamic properties of the system. The modified associate species model was used for the description of the liquid phase. Particular attention was given to two significant solid solution phases: Spinel with the formula Zn(2-x)Sn(1-x)In2xO4 based on Zn2SnO4 and Bixbyite based on In2O3 and extending strongly toward the SnZnO3 composition according to the formula In(2‑2x)SnxZnxO3. In addition to the component oxides, nine quasi-binary compounds located in the In2O3-ZnO binary subsystem have also been included in the database as stoichiometric phases.

Liquid-liquid equilibrium and critical states for the quaternary system propionic acid–n-butanol–n-butyl propionate–water at 303.15 K

New experimental data on liquid-liquid equilibrium (LLE) and critical phases for the propionic acid – n-butanol – n-butyl propionate – water system at 303.15 K and atmospheric pressure are presented. The LLE compositions were determined by gas chromatography, correlated and predicted by NRTL and UNIFAC models respectively. The results of NRTL and UNIFAC modelling are in sufficient agreement with experimental data. Standard deviations for binary and ternary subsystems do not exceed 0.79% (NRTL) and 5.1% (UNIFAC). In case of quaternary system investigated σ(NRTL) = 0.56% and σ(UNIFAC) = 2.2%. The study of critical states was carried out by “cloud-point technique” method. The run of critical curve in quaternary system was studied.

Solubility and Critical Phenomena in Ternary Aqueous Solutions Containing Type-2 Salt and Alkali

Supercritical phase equilibria in the ternary system K2SO4–KOH–H2O at 420–500°C and up to 130 MPa pressure with binary boundary subsystems of different types are studied. The binary subsystem of type 1 features no critical phenomena in saturated (l = g) aqueous solution and no phase separation (l1–l2) (KOH–H2O); the binary subsystem of type 2 is characterized by immiscibility of the liquid phase and has two critical end-points \(p(g = l-_{S_{K_{2}SO_{4}}})\) and \(Q(l_{1} = l_{2}-_{S_{K_{2}SO_{4}}})\) in saturated aqueous solution (K2SO4–H2O). The ternary system has two three-phase equilibria (g–l–s) and (l1–l2–s), separated by a two-phase supercritical fluid region \((fl-_{S_{K_{2}SO_{4}}})\), and two types of monovariant critical curves \((g=l-_{S_{K_{2}SO_{4}}})\) and \((l_{1}=l_{2}-_{S_{K_{2}SO_{4}}})\). The three-phase regions approach each other upon temperature increase up to the point where the two-phase supercritical equilibrium disappears, and the two mentioned monovariant critical curves are joined into a double homogeneous critical point \((g=l-_{S_{K_{2}SO_{4}}} \leftrightarrow l_{1} = l_{2}-_{S_{K_{2}SO_{4}}})\) at maximum temperature ~445°C and 51–52 MPa.

Experimental investigation of solidification and isothermal sections at 1000 and 1100 °C in the Al-Fe-Mn-C system with special attention to the kappa-phase

Phase equilibria in the Al-Fe-(10-20)Mn-C system upon solidification and at 1100 and 1000 °C were studied using DTA, X-ray diffraction, SEM and electron probe microanalysis. The partial liquidus and solidus projections and the isothermal sections at 1100 and 1000 °C for the Al-Fe-10Mn-C and Al-Fe-20Mn-C systems were constructed. The compound Al(Fe,Mn)3C (κ-phase) (antiperovskite structure CaTiO3-type, ≿Р5-Pm-3m) melts congruently at ∼1300 °C. The liquidus surfaces in the studied regions are characterized by the regions of primary crystallization of γ, α, κ, M3C and graphite (C). The solidus surfaces and isothermal sections at 1100 and 1000 °C of the Al-Fe-10Mn-C system in the studied region are defined by the co-existence of the κ-phase with almost all phases of the binary subsystems, except M3C: γ, α and graphite (С). The solidus surfaces and isothermal sections at 1100 and 1000 °C of the Al-Fe-20Mn-C system in the studied region are defined by the co-existence of the κ-phase with all phases of the binary subsystems, including M3C.

First-principles prediction of high-entropy-alloy stability

High entropy alloys (HEAs) are multicomponent compounds whose high configurational entropy allows them to solidify into a single phase, with a simple crystal lattice structure. Some HEAs exhibit desirable properties, such as high specific strength, ductility, and corrosion resistance, while challenging the scientist to make confident predictions in the face of multiple competing phases. We demonstrate phase stability in the multicomponent alloy system of Cr–Mo–Nb–V, for which some of its binary subsystems are subject to phase separation and complex intermetallic-phase formation. Our first-principles calculation of free energy predicts that the configurational entropy stabilizes a single body-centered cubic (BCC) phase from T = 1700 K up to melting, while precipitation of a complex intermetallic is favored at lower temperatures. We form the compound experimentally and confirm that it develops as a single BCC phase from the melt, but that it transforms reversibly at lower temperatures.

Phase formation in alloy-type anode materials in the quaternary system Li–Sn–Si–C

AbstractInvestigations on the thermodynamics of alloy-type anode materials have been carried out for the quaternary Li–C–Si–Sn system. Phase equilibria and phase stabilities were characterized in the binary subsystems Li–C, Li–Si, Li–Sn. The Calphad method was first used to optimize or completely re-establish all binary subsystems containing Li. For reasons of consistency, the binary subsystem Si–C had to be revisited and its Calphad description was modified. The ternary phase diagrams were then tentatively calculated by extrapolation from the binary subsystems and confirmed by key experiments. No ternary compounds were found. In order to verify the applicability of the anode materials in real batteries, some of the materials were nanostructured by ball milling and spark plasma sintering, the corresponding nanostructures were characterized. Theoretical predictions that nanograined Li2C2 can also be used as cathode material were verified experimentally. The methodologies worked out in the present project (e. g. nanoscale structure transmission electron microscopy analysis, glow discharge optical emission spectroscopy) were also employed in other projects and led to publications concerning other materials such as Mg alloys, carbon nanofibers and an Mn-based antiperovskite.

Thermodynamic re-assessment of the Al-Co-W system

The Al-Co-W system and its binary sub-systems Al-Co, Al-W and Co-W were critically reviewed. The thermodynamic description of the Al-Co-W system including all three binaries was developed considering thermodynamic and constitutional data of the systems. Results from density functional theory calculations were employed to improve reliability of the descriptions. The Gibbs energy for the thermal vacancy (GVa) in the BCC_A2 phase is discussed. The revised descriptions obtained for the Al-W and Co-W systems describe the thermodynamic and phase equilibrium data well and are free of undesired artefacts for temperatures below 6000K. The ordered γ’ phase of the Al-Co-W system is described as a metastable phase in the entire temperature range. The calculated Gibbs energy of the γ’ is only slightly above that of the equilibrium state, which indicates that there is good possibility of stabilizing the γ’ phase with the addition of γ’-stabilizing elements, such as Ti, Ta, Hf, Nb and Ni.

Water Activity and Phase Equilibria Measurements and Model Simulation for the KCl–SrCl2–H2O System at 323.15 K

Water activities for the ternary system of KCl–SrCl2–H2O and its sub-binary system SrCl2–H2O were elaborately measured using an isopiestic method at 323.15 K. The solubility isotherms for the KCl–SrCl2–H2O system were determined by the isothermal equilibrium method. It is found that the measured isopiestic composition lines for the KCl–SrCl2–H2O system deviated from the Zdanovskii rule, especially at a lower water activity. The Pitzer–Simonson–Clegg model was used to correlate the measured water activity and solubility data, simulate the thermodynamic properties, and predict the solubility of the ternary system. The reliability of the solubility data measured in this work was evaluated by comparing with the solubility isotherms calculated with the Pitzer–Simonson–Clegg model. The measured water activity and solubility results are of great importance for predicting the phase diagram of other multicomponent systems that related to this ternary system.

Thermodynamic modelling of a six component (C-Co-Cr-Ni-Ta-W) system for the simulation of Cobalt based alloys

Co-based alloys are key materials for several high temperature applications where high corrosion and wear resistance are required. Main alloying elements, in addition to Co, are Cr, Ni, Ta, Mo, W, Ti, Al, etc. and C. In order to simulate these materials a new thermodynamic database has been implemented which includes the six most important alloying elements: Co, Cr, Ni,Ta, W and C.The liquid and 30 solid phases have been modelled by means of the Compound Energy Formalism (CEF) with particular attention to the consistency between thermodynamic and crystallographic sublattices. Interaction parameters for all the binary and ternary sub-systems are included. When possible they have been taken from the literature but, for several systems, partial or complete reassessment was needed, due to inconsistency of the phase models or incompatibility between assessments of different authors. As a result phase equilibria in selected commercial alloys are calculated.

Experimental study on phase relations in the Ce-Fe-Sb ternary system

This paper describes the experimental study on the liquidus projection and the isothermal section at 823 K of the Ce-Fe-Sb ternary system. The microstructures and solidification paths of the as-cast alloys were analyzed. The constituent phases and their equilibrium compositions of the as-cast and the heat-treated alloys were determined. The microstructure observation, the phase identification and the composition measurement were performed using scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron probe microanalysis (EPMA), respectively. The existence of three ternary compounds Ce2Fe4Sb12 (τ1), CeFeSb2 (τ2), and Ce2Fe4Sb5 (τ3) were confirmed. For the liquidus projection over the entire composition range, there are 17 primary solidification regions, 4 eutectic invariant reactions, and 15 pseudo-eutectic invariant reactions. Some of the primary solidification regions and invariant four-phase reaction types were determined with the help of the thermodynamic assessment of the system. And then the whole liquidus projection of the Ce-Fe-Sb ternary system was constructed. For the isothermal section at 823 K over the entire composition range, there are 14 single-phase regions, 28 two-phase regions, and 15 three-phase regions. Based on the present experimental measurements as well as the phase diagrams of the three binary subsystems, Ce-Fe, Ce-Sb and Fe-Sb, the liquidus projection and the isothermal section at 823 K of the Ce-Fe-Sb ternary system were constructed.

Thermodynamic reassessment of the novel solid-state thermal energy storage materials: Ternary polyalcohol and amine system pentaglycerine-tris(hydroxymethyl)-amino-methane-neopentylglycol (PG-TRIS-NPG)

Organic polyalcohol and amine globular molecular crystals such as PG, TRIS, and NPG are considered as the most promising potential candidates for solid-state thermal energy storage in the orientationally disordered high temperature phases. In this study, we first propose a new PG-TRIS-NPG phase diagram based on experimental data of the three sub-binary systems NPG-PG, PG-TRIS, and NPG-TRIS with CALPHAD methodology. The NPG-PG binary phase diagram was optimized using sub-regular models that showed complete miscibility in the entire compositional range of high temperature γ′ (FCC) phase region, and an invariant equilibrium point at 299.5K. The NPG-TRIS binary system was also calculated using sub-regular model, from sub-ambient to well above the melting temperatures, and determined three invariant equilibria at 311.1K, 391.8K, and 410.6K, respectively. These calculated binary phase diagrams are in good agreement with the experimental data. The PG-TRIS-NPG ternary system has also been calculated and qualitatively analyzed using the CALPHAD method and Thermo-Calc software. A set of self-consistent thermodynamic parameters formulating the Gibbs energies of various phase in the PG-TIRS-NPG ternary system are obtained in the present work. Thermodynamic properties such as several isotherms, isopleths, and liquidus projections are calculated by using present datasets as shown in this work in which the solid ternary compound (TRIS0.5NPG0.5)XPG1−X (0.1≤x≤0.9), (TRIS0.5PG0.5)XNPG1−X (0.1≤x≤0.9), and (PG0.5NPG0.5)XTRIS1−X (0.1≤x≤0.9) with various solid-solid phase transitions at different temperatures could apply to applications in the solid-state thermal energy storage.

Experimental investigation and thermodynamic description of the Cu-Cr-Zr system

The Cu-Cr-Zr ternary system was investigated via thermodynamic modeling coupled with key experiments. The isothermal section of the Cu-Cr-Zr system at 1123K was determined by means of optical microscopy, X-ray diffraction and electron probe microanalysis, and the phase transformation temperatures were measured by differential scanning calorimetry. The Cu-Cr sub-binary system was re-assessed with a substitutional solution model for the solution phases to ensure its compatibility in multi-component system. A set of self-consistent thermodynamic parameters for the Cu-Cr-Zr systems was obtained using the CALPHAD (CALculation of PHAse Diagram) approach, and the calculated phase diagram is in a satisfactory agreement with the present experimental results and literature information. An increase of the thermodynamic stability for the CuZr and Cr2Zr phases due to the ternary solubility is verified by calculation.

Thermodynamic Calculation of Phase Equilibria in the Mn-RE (RE=Nd, Gd, Dy) Binary Systems

Ternary intermetallic compounds with rare earth elements and transition metals in the RE-Mn-X (X=Si, Ge, Sn etc.) ternary systems show interesting magnetic properties. As key sub-binary systems of the RE-Mn-X (X=Si, Ge, Sn etc.) ternary systems, the information of phase equilibria and thermodynamic properties of the Mn-RE (RE=Nd, Gd, Dy) binary systems are indispensable to explore the RE-Mn-X (X=Si, Ge, Sn etc.) alloys with better magnetic properties. In this work, the experimental data of phase equilibria and thermodynamic properties of the Mn-RE (RE=Nd, Gd, Dy) binary systems in the published literature were reviewed. Based on the available experimental information, thermodynamic calculation of phase equilibria of the Mn-RE (RE=Nd, Gd, Dy) binary systems was performed using the CALPHAD method. As a result, further experimental investigation and thermodynamic optimization would be still necessary in order to develop the self-consistent and compatible thermodynamic database of the RE-Mn-based alloy systems.

Hill stability of the coplanar four-body problem with a binary subsystem

Hill stability of the coplanar four-body problem with a binary subsystem

Na2SO4–NaCl–H2O system with a binary homogeneous critical point: Phase equilibria at 475–520°C and to 130 MPa

Phase equilibria were studied at temperatures 475–520°C and a pressure to 130 MPa in the ternary system Na2SO4–NaCl–H2O with boundary binary subsystems of two types. In type 1 subsystems (the NaCl–H2O subsystem in this work), there are no critical phenomena in saturated solutions. Type 2 subsystems (the Na2SO4–H2O subsystem in this work) have terminal critical points p (G = L – $${S_{N{a_2}S{O_4}}}$$ ) and Q (L1 = L2 – $${S_{N{a_2}S{O_4}}}$$ ). It was shown that the ternary system contains two regions of three-phase equilibria ((G–L–S) and (L1–L2–S)), divided by a two-phase fluid region (F – $${S_{N{a_2}S{O_4}}}$$ ), and two types of monovariant critical curves ((G = L – $${S_{N{a_2}S{O_4}}}$$ ) and (L1 = L2 – $${S_{N{a_2}S{O_4}}}$$ )). With increasing temperature, these three-phase regions approach each other until the two-phase fluid equilibrium vanishes and the monovariant critical curves meet at a binary homogeneous critical point (G = L–S ⇔ L1 = L2 – $${S_{N{a_2}S{O_4}}}$$ ) at a maximal temperature of ~495°C and a pressure of ~75 MPa.

Isobaric Vapor–Liquid–Liquid Phase Equilibria Measurements of Three Ternary Water + 2-Butanone + Aliphatic Alcohol (Ethanol, 1-Propanol, 2-Propanol) Systems at 101.3 kPa

Vapor–liquid–liquid equilibrium (VLLE) data were measured for the ternary systems water + 2-butanone + alcohol at 101.3 kPa by means of a Gillespie type still equipped with an ultrasonic homogenizer. VLLE were observed in the temperature ranges of 346.65–346.79 K, 346.74–352.70 K, and 346.52–346.75 K for the water + 2-butanone + ethanol, water + 2-butanone + 1-propanol, and water + 2-butanone + 2-propanol systems, respectively. For all three systems, a region of liquid–liquid immiscibility was observed, and the vapor phase compositions were outside the liquid–liquid phase envelope. The absence of ternary heterogeneous azeotropes was thus established. The nonrandom two-liquid (NRTL), universal quasichemical (UNIQUAC), and universal functional (UNIFAC) activity coefficient models were used for comparison with experimental results. The parameters were fitted to the binary subsystems vapor–liquid and liquid–liquid equilibrium experimental data. While correct estimations of experimental vapor phase trends were...