Modeling of molar volume for the Ni–Al γ/γ′ binary phases within the framework of CALPHAD method

The CALPHAD method has been employed to compose thermodynamic description of the Fe–Cr–Mn–Ni–Si–C–N system. Using an algorithm based on finding a global minimum of Gibbs energy, the calculations of system phase composition were performed in the temperature range from 1750°C to hardening and in the range of compositions corresponding to 04Kh20N6G11M2AFB steel. Calculations showed that at temperatures above liquidus line, Cr and Mn increase nitrogen solubility in the melt, while Ni and Si reduce it. With an increase in the content of Cr, Mn, Ni, and Si in steel in the studied composition range, both liquidus and solidus temperature decrease. The degree of influence on these temperatures of Cr, Mn, Ni and Si within the steel grade is different and ranges from ~3 to ~14°C. Calculations taking into account the possibility of nitrogen transfer between steel and the atmosphere of air showed that the amount of fixed nitrogen in the alloy under study varies, depending on the composition of the steel and temperature, from ~0.3 to ~0.6 wt%. As the temperature decreases from liquidus to solidus, the amount of fixed nitrogen increases, with the exception of those steel compositions when ferrite and not austenite is released from the liquid phase.

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Behavior and properties of water in silicate melts under deep mantle conditions

Scientific Reports ◽

10.1038/s41598-021-90124-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Bijaya B. Karki ◽

Dipta B. Ghosh ◽

Shun-ichiro Karato

Keyword(s):

Electrical Conductivity ◽

Molar Volume ◽

Water Solution ◽

Pure Water ◽

Electrical Conductance ◽

Water Structure ◽

Bulk Water ◽

Silicate Melts ◽

Pressure Regime ◽

Low Pressures

AbstractWater (H2O) as one of the most abundant fluids present in Earth plays crucial role in the generation and transport of magmas in the interior. Though hydrous silicate melts have been studied extensively, the experimental data are confined to relatively low pressures and the computational results are still rare. Moreover, these studies imply large differences in the way water influences the physical properties of silicate magmas, such as density and electrical conductivity. Here, we investigate the equation of state, speciation, and transport properties of water dissolved in Mg1−xFexSiO3 and Mg2(1−x)Fe2xSiO4 melts (for x = 0 and 0.25) as well as in its bulk (pure) fluid state over the entire mantle pressure regime at 2000–4000 K using first-principles molecular dynamics. The simulation results allow us to constrain the partial molar volume of the water component in melts along with the molar volume of pure water. The predicted volume of silicate melt + water solution is negative at low pressures and becomes almost zero above 15 GPa. Consequently, the hydrous component tends to lower the melt density to similar extent over much of the mantle pressure regime irrespective of composition. Our results also show that hydrogen diffuses fast in silicate melts and enhances the melt electrical conductivity in a way that differs from electrical conduction in the bulk water. The speciation of the water component varies considerably from the bulk water structure as well. Water is dissolved in melts mostly as hydroxyls at low pressure and as –O–H–O–, –O–H–O–H– and other extended species with increasing pressure. On the other hand, the pure water behaves as a molecular fluid below 15 GPa, gradually becoming a dissociated fluid with further compression. On the basis of modeled density and conductivity results, we suggest that partial melts containing a few percent of water may be gravitationally trapped both above and below the upper mantle-transition region. Moreover, such hydrous melts can give rise to detectable electrical conductance by means of electromagnetic sounding observations.

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Phase Diagram of Binary Alloy Nanoparticles under High Pressure

Materials ◽

10.3390/ma14112929 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2929

Author(s):

Han Gyeol Kim ◽

Joonho Lee ◽

Guy Makov

Keyword(s):

Phase Diagram ◽

Phase Diagrams ◽

Interaction Parameter ◽

Excess Volume ◽

Eutectic Temperature ◽

Calphad Method ◽

Alloy Nanoparticles ◽

Thermodynamic Conditions ◽

Nanoparticle System ◽

Pressure Phase

CALPHAD (CALculation of PHAse Diagram) is a useful tool to construct phase diagrams of various materials under different thermodynamic conditions. Researchers have extended the use of the CALPHAD method to nanophase diagrams and pressure phase diagrams. In this study, the phase diagram of an arbitrary A–B nanoparticle system under pressure was investigated. The effects of the interaction parameter and excess volume were investigated with increasing pressure. The eutectic temperature was found to decrease in most cases, except when the interaction parameter in the liquid was zero and that in the solid was positive, while the excess volume parameter of the liquid was positive. Under these conditions, the eutectic temperature increased with increasing pressure.

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Sorption of phenols on hexadecyltrimethylammonium- modified bentonite: Application of Polanyi−Manes potential theory

Energy & Environment ◽

10.1177/0958305x20977286 ◽

2020 ◽

pp. 0958305X2097728

Author(s):

Jiyeon Choi ◽

Dong-Ik Slong ◽

Won Sik Shin

Keyword(s):

Molar Volume ◽

Potential Theory ◽

Characteristic Curve ◽

Chemical Compositions ◽

Pore Filling ◽

Sorption Data ◽

Similar Chemical ◽

Competitive Model ◽

Sorption Potential ◽

Sorption Systems

This study investigated the sorption of phenol and 4-chlorophenol (4-CP) on natural bentonite modified with hexadecyltrimethylammonium (HDTMA) cation. The Freundlich, Langmuir, Dubinin−Radushkevich (DR), Sips, and Polanyi−Dubinin−Manes (PDM) models fitted the sorption data well (R2 > 0.92). The Freundlich coefficient and the maximum sorbed amount of the Langmuir and PDM models of 4-CP were higher than phenol because of higher hydrophobicity (log Kow = 2.39 for 4-CP and 1.46 for phenol). The PDM model that includes solubility and molar volume was highly useful in predicting the sorption of phenols having widely different hydrophobicity and solubility. The characteristic curves, the plot of sorbed volume ( qv) versus the sorption potential per molar volume ( ε/ Vm) of 4-CP and phenol were distinctly different although they have similar chemical compositions. The selectivity of 4-CP (3.72) was higher than that of phenol (0.27) in binary sorption systems. The sorbed volume ( qv) in the binary sorption was remarkably reduced and the characteristic curve had wider distribution owing to competition in pore-filling. The sorption behaviors were elucidated by partitioning and pore-filling mechanisms. Among the tested binary sorption models, the modified Langmuir competitive model was the best in the prediction of the binary sorption (R2 > 0.98).

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Determination of density and excess molar volume of dimethyl sulfoxide + 1-allyl-3-methylimidazolium chloride mixtures at high pressure

The Journal of Supercritical Fluids ◽

10.1016/j.supflu.2017.07.040 ◽

2017 ◽

Vol 130 ◽

pp. 76-83 ◽

Cited By ~ 3

Author(s):

Laura de Pablo Nisa ◽

José J. Segovia ◽

Ángel Martín ◽

M. Carmen Martín ◽

M. Dolores Bermejo

Keyword(s):

High Pressure ◽

Dimethyl Sulfoxide ◽

Molar Volume ◽

Excess Molar Volume

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Apparent molar volume, compressibility and viscometric studies of sodium dodecyl benzene sulfonate (SDBS) and dodecyltrimethylammonium bromide (DTAB) in aqueous amino acid solutions: A thermo-acoustic approach

Thermochimica Acta ◽

10.1016/j.tca.2013.12.021 ◽

2014 ◽

Vol 578 ◽

pp. 15-27 ◽

Cited By ~ 29

Author(s):

Kundan Sharma ◽

S. Chauhan

Keyword(s):

Amino Acid ◽

Molar Volume ◽

Apparent Molar Volume ◽

Sodium Dodecyl ◽

Sodium Dodecyl Benzene Sulfonate ◽

Dodecyltrimethylammonium Bromide ◽

Acid Solutions ◽

Benzene Sulfonate ◽

Amino Acid Solutions ◽

Dodecyl Benzene Sulfonate

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Notizen: Näherungsforniel für den Koeffizienten der thermischen Ausdehnung von assoziationsfreien flüssigen Nichtelektrolyten / Approximation Formula for the Thermal Expansion of Nonassociated Nonelectrolytic Liquids

Zeitschrift für Naturforschung A ◽

10.1515/zna-1974-0718 ◽

1974 ◽

Vol 29 (7) ◽

pp. 1112-1116

Author(s):

Raimund Ulbrich

Keyword(s):

Thermal Expansion ◽

Molar Volume ◽

Polyatomic Molecules ◽

Approximation Formula ◽

Dispersion Force ◽

Effective Electron ◽

Numeric Data

For the calculation of the thermal expansion of nonassociated liquids in terms of molar volume, mol refraction and the "effective electron numbers" a corrected approximation formula is proposed. The thermal expansion of 26 solvents is calculated. - The usefulness of the "effective electron numbers" for the derivation of numeric data for dispersion force potentials of polyatomic molecules is affirmed once more.

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