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Thermodynamic Calculation of Phase Equilibria in As Fe In Ternary System Based on CALPHAD Approach

Thermodynamic Calculation of Phase Equilibria in As Fe In Ternary System Based on CALPHAD Approach

Thermodynamic calculation of phase equilibria in As-Fe-In ternary system is performed based on Calphad approach, directing a special attention to fabrication process of Fe/InAs hybrid structure for spin injection device. For this, the thermodynamic assessment of Fe-In binary system is first carried out utilizing reported experimental data. Then, the liquidus surface of the ternary system and invariant reactions are calculated. The isothermal sections in low temperature region are presented and discussed in the light of the optimization of the growth temperature of Fe film on InAs substrate during the fabrication process. [doi:10.2320/matertrans.MER2008437]

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Experimental investigation and thermodynamic calculation of Ni–Al–La ternary system in nickel rich region: A new intermetallic compound Ni2AlLa

Experimental investigation and thermodynamic calculation of Ni–Al–La ternary system in nickel rich region: A new intermetallic compound Ni2AlLa

The enthalpies of mixing of the ternary liquid at different sections were measured by Feufel et al. [48] with an adiabatic calorimeter. Sommer and Schmid [49,50] adopted the same method to study the heat of the liquid Ni–Al–La alloy, but the liquidus temperature values of the Ni–Al–La alloys obtained from Cp–measurements were very low in comparison to the melting temperatures of the alloy, which resulted in the Cp values of their work exceeding the actual value. Thus, their thermodynamic optimization procedure is not utilized in this work. Additionally, Pasturl et al. [51] and Borzone et al. [52] used isoperibol calorimetry and a high-temperature direct-reaction drop calorimeter, respectively, to determine the formation of Ni 4 AlLa and NiAlLa ternary intermetallic compounds.

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Thermodynamic Calculation of Phase Diagram in the Bi In Sb Ternary System

Thermodynamic Calculation of Phase Diagram in the Bi In Sb Ternary System

provide the information of not only phase equilbria but also physical properties of liquid phase such as surface tension and viscosity. Since Bi, In and Sb are important elements for the development of Pb-free solders, the thermodynamic description of the Bi–In–Sb system is required for the ac- curate prediction of melting temperature, phase constitution, solidification behavior etc. in the multi-component alloy sys- tems. In addition, some investigations 5, 6) have revealed that

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Thermodynamic Calculation for Silicon ModifiedAISI M2 High Speed Tool Steel

Thermodynamic Calculation for Silicon ModifiedAISI M2 High Speed Tool Steel

loy 6-5-2-1 Si. According to the calculations, this carbide should crystallize at 1286˚C, and should continue in con- tact with the melt down to 1246˚C. Below this, only solid phases should be found. Since the austenitization treat- ment of this steel is performed at about 1230˚C, it should produce a state close to the thermodynamic equilibrium. Therefore, the compositions of the carbides after austeni- tization (and quenching and tempering, which causes no further changes in the blocky carbides) may be used here as a legitimate basis for comparison. The calculated phase compositions and the measured values are presented Table 4. Calculated and measured liquidus and solidus temperature at the AISI M2 and its three silicon variants.

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Thermodynamic Calculation of Phase Equilibria in the Nb Ni Ti Zr Quaternary System

Thermodynamic Calculation of Phase Equilibria in the Nb Ni Ti Zr Quaternary System

The phase equilibria in the Nb-Ni-Ti-Zr quaternary system have been studied using the CALPHAD method. Among the four ternary systems present in the quaternary phase diagram, the Nb-Ti-Zr ternary system was described using a simple ternary extrapolation of the constituent binary systems with no additional ternary parameters. The thermodynamic parameters of the Ni-Ti-Zr ternary system were evaluated using data from first-principles calculations on the ternary NiTi, NiZr, and NiTiZr compound phases as well as available experimental data on the phase boundaries. The calculated isothermal and vertical section diagrams of both the Nb-Ti-Zr and Ni-Ti-Zr ternary systems reproduced the experimental results satisfactorily. The thermodynamic parameters of the Nb-Ni-Ti and Nb-Ni-Zr ternary systems were adopted from previous studies. The liquidus surface in the Nb-Ni-Ti-Zr quaternary system was calculated based on the thermodynamic description of the ternary systems. According to the calculated liquidus surface of Nb 40xy Ni 60 Ti x Zr y alloys, in which a metallic glass was formed over a wide

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Research on Numerical Simulation of Three dimensional Icing for Aircraft and Aero engine

Research on Numerical Simulation of Three dimensional Icing for Aircraft and Aero engine

Abstract. Based on the idea of modularization, the three-dimensional icing calculation research code for aircraft and aero-engine is developed by using the secondary development features (UDF) of FLUENT. By analyzing the physical process of aircraft and engine inlet parts icing, two-phase flow field calculation, water droplets collect calculation, thermodynamic calculation of icing, wall mesh calculation program is compiled, four calculation modules of icing calculation program were realized. By solving the key problem of data exchange and control solution process between the secondary development program and the four calculation modules, the module integration is completed and the three-dimensional icing numerical simulation of icing components of aircraft and aero-engine was realized. The calculation of icing on NACA0012 3D airfoil is carried out, and compared with the experimental results in literature. The results show that the maximum icing thickness is in good agreement with the experimental results, and the predicted ice shape is consistent with the experimental ice shape development trend. The calculation results show that the proposed three-dimensional icing calculation method is effective and reliable. On the basis of this, numerical simulation of icing was carried out on the trailing adjusted strut of aero-engine inlet with a tail angle of 0 °, and the water collection coefficient of the strut wall and the icing area of the strut at different time were obtained. It provides a new method for pre-researching aircraft and aero-engine icing.

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Solidification Microstructure and Magnetic Properties of Ag Rich Ag Cu La Fe Immiscible Alloys

Solidification Microstructure and Magnetic Properties of Ag Rich Ag Cu La Fe Immiscible Alloys

type amorphous alloys with BCC-Fe globules was not detected. In the thermodynamic calculation results focusing on the liquid miscibility gap (Fig. 1(b)), the temperature of the liquid miscibility gap was much higher than the melting point of pure Fe (1811 K), and single liquid phase was not obtained at and above 2273 K. Table 2 showed that Fe-rich and Ag­Cu­La-rich liquids were formed through liquid- phase separation. Based on the thermodynamic calculation results, the following process was considered as the candidate mechanism for the formation of a particular solidification microstructure composed of BCC-Fe globules and Ag­Cu­ La-rich crystalline matrix: (1) liquid-phase separation occurred, resulting in the formation of the main Ag-rich Ag ­ Cu ­ La-rich and minor Fe-rich liquids, (2) main Ag-rich Ag ­ Cu ­ La-rich liquid exhibited supercooling because the composition of Ag ­ Cu ­ La-rich liquid was similar to that of ternary Ag­Cu­La alloy with high GFA, (3) minor Fe- rich dispersed liquid was crystallized to BCC-Fe nano-

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Comparative Study of Pyridine and Pyrimidine Derivatives as Corrosion Inhibitors of C38 Steel in Molar HCl

Comparative Study of Pyridine and Pyrimidine Derivatives as Corrosion Inhibitors of C38 Steel in Molar HCl

Corrosion inhibition of C38 steel in 1 M HCl was investigated in the absence and presence of different concentrations of two imidazo derivatives namely, 2-phenylimidazo[1,2-a]pyridine (P1) and 2-(m- methoxyphenyl) imidazo[1,2-a]pyrimidine (P5). Weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy techniques were employed. Impedance measurements showed that the double-layer capacitance decreased and charge-transfer resistance increased with increase in the inhibitors concentration and hence increasing in inhibition efficiency. Potentiodynamic polarization study showed that all the inhibitors act as mixed-type inhibitors. The inhibitors were adsorbed on the steel surface according to the Langmuir adsorption isotherm model. From the adsorption isotherm, some thermodynamic data for the adsorption process were calculated and discussed. Kinetic parameters activation such as activation energy, pre-exponential factor, enthalpy of activation and entropy of activation were evaluated from the effect of temperature on corrosion and inhibition processes. E (%) values obtained from various methods used are in good agreement.

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A computationally efficient and accurate numerical representation of thermodynamic properties of steam and water for computations of non-equilibrium condensing steam flow in steam turbines

A computationally efficient and accurate numerical representation of thermodynamic properties of steam and water for computations of non-equilibrium condensing steam flow in steam turbines

There are essentially two ways of representing thermodynamic properties. The first one is by a global analytical equation. The second is the so-called table look-up. The second way may provide very quick evaluations of thermodynamic properties. The fact that it requires a larger memory capacity (order of 10 MB) is not a difficulty for present machines. Real trouble of the available methods is discontinuity at the borders between the tabulated cells. The CFD solvers assume some level of smoothness (continuity of derivatives up to certain order). The discontinuities cause a quasi-random noise which can deteriorate the performance of the solver or even lead to lack of convergence or unphysical oscillations. An advanced table look up method was developed by Miyagawa and Hill [5,6]. It is based on the second-order Taylor expansion of a thermodynamic potential with respect to two variables (e.g. density and temperature [6]). Six coefficients of the expansion are tabulated for each cell, enabling computation of any thermodynamic property.

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Using generalized anharmonic – correlated einstein model in xafs theory for calculation the thermodynamic parameters and cumulants of dopant bcc crystals

Using generalized anharmonic – correlated einstein model in xafs theory for calculation the thermodynamic parameters and cumulants of dopant bcc crystals

A new procedure for calculation and analysics of X-ray absorption fine structure (XAFS) cumulants of mixed body center cubic (bcc) crystals has been derived based on quantum statistical theory with generalized anharmonic correlated Einstein model. This study has formulated the expressions that are describing asymmetric component for dopant bcc crystals such as the first cumulant or net thermal expansion, the second cumulant or mean square relative displacement (MSRD), the third cumulant, and thermodynamic parameters including the anharmonic effects contributions of body center cubic crystals have been doped with Einstein frequency, Einstein temperature, and thermal expansion coefficient constant. Numerical results for pure Iron (Fe) and pure Molybdenium (Mo), and Fe doped by Mo (FeMo) are found to be good agreement with experimental.

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Calculation of Thermodynamic Properties and Phase Diagrams for the CaO CaF2, BaO CaO and BaO CaF2 Systems by Molecular Dynamics Simulation

Calculation of Thermodynamic Properties and Phase Diagrams for the CaO CaF2, BaO CaO and BaO CaF2 Systems by Molecular Dynamics Simulation

The run durations of all simulations were carried out for 30000 time steps. At the region around the critical points such as phase transition temperatures, the simulations were carried out using long runs up to 100000 time steps. The simulations for solid phases were started from the room temperature structures of each solid crystal and then heated up to the required temperatures. The simulations for liquid phases were heated to the initial temperature of 4000 K and thermally equilibrated during the 30000 time steps in order to stabilize the highly energetic atomic configurations of initial cells, and then were cooled stepwise from 4000 to 1400 K. In this study, the effect of cooling rate on the MD calculation results of all simulation systems has been verified using cooling rate of 0.1 K per step and relevant differences were not observed. Therefore, in this study, the effect of cooling rate was assumed to be negligible. The various properties for the each system were calculated by statistical analyses of velocities and positions data after reaching the thermal equilibrium of each stimulation system. All MD calculations were carried out using WinMASPHYC program (Fujitsu).

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Calculation of Kinetic and Thermodynamic Parameters of Gel-Grown Lead-Cobalt Mixed Levo-Tartrate Crystals by C-R Relation

Calculation of Kinetic and Thermodynamic Parameters of Gel-Grown Lead-Cobalt Mixed Levo-Tartrate Crystals by C-R Relation

ABSTRACT: Metal tartrate compounds find various applications. Lead tartrate finds application as additive in gasoline to prevent knocking in motors and calcium tartrate is well known for its ferroelectric applications. In the present study, lead and cobalt mixed levo-tartrate crystals were grown using silica hydro-gel as growth medium. Dendrite crystals were obtained at the gel-liquid interface. The crystals were characterized by Thermo gravimetric analysis and kinetic as well as thermodynamic parameters were evaluated for the dehydration and carbonate stage by C- R relation.

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Thermodynamic Modelling

Thermodynamic Modelling

The energies from a first principle calculation can also be used directly in a sublattice model if the configurations correspond to the end members. For fcc there are theoretically 3 ordered compounds, two with L1 2 and one with L1 0 structure. But like in the Al-Ni system below some may be metastable and their energies must be calculated using ab initio techniques.

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Thermochemistry of Heteroatomic Compounds: Analysis and Calculation of Thermodynamic Functions of Organic Compounds of V-VII Groups of Mendeleev’s Periodic Table

Thermochemistry of Heteroatomic Compounds: Analysis and Calculation of Thermodynamic Functions of Organic Compounds of V-VII Groups of Mendeleev’s Periodic Table

[36] Steele W.V., Chirico R.D., Knipmeyer S.E., Nguyen A. and Smith N.K., Thermodynamic properties and ideal-gas enthalpies of formation for butyl vinyl ether, 1,2- dimethoxyethane, methylglycolate, bicyclo[2. 2.1]hept-2- ene,5-vinylbicyclo- [2.2.1]hept-2- ene, trans-azobenzene, butyl acrylate, di-tert- butyl ether, and hexane-1,6-diol, J. Chem. Eng. Data, 41, 1285-1302 (1996).

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Biochemical and Thermodynamic Analyses of Salmonella enterica Pat, a Multidomain, Multimeric Nε Lysine Acetyltransferase Involved in Carbon and Energy Metabolism

Biochemical and Thermodynamic Analyses of Salmonella enterica Pat, a Multidomain, Multimeric Nε Lysine Acetyltransferase Involved in Carbon and Energy Metabolism

(GNAT) Pat control carbon utilization and metabolic flux via N ␧ -lysine acetylation/deacetylation of metabolic enzymes. To date, the S. enterica Pat (SePat) acetyltransferase has not been biochemically characterized. Here we report the kinetic and thermody- namic characterization of the SePat enzyme using two of its substrates, acetyl coenzyme A (Ac-CoA) synthetase (Acs; AMP form- ing, EC 6.2.1.1) and Ac-CoA. The data showed typical Michaelis-Menten kinetic behavior when Ac-CoA was held at a saturating concentration while Acs was varied, and a sigmoidal kinetic behavior was observed when Acs was saturating and the Ac-CoA concentration was varied. The observation of sigmoidal kinetics and positive cooperativity for Ac-CoA is an unusual feature of GNATs. Results of isothermal titration calorimetry (ITC) experiments showed that binding of Ac-CoA to wild-type SePat pro- duced a biphasic curve having thermodynamic properties consistent with two distinct sites. Biphasicity was not observed in ITC experiments that analyzed the binding of Ac-CoA to a C-terminal construct of SePat encompassing the predicted core acetyl- transferase domain. Subsequent analytical gel filtration chromatography studies showed that in the presence of Ac-CoA, SePat oligomerized to a tetrameric form, whereas in the absence of Ac-CoA, SePat behaved as a monomer. The positive modulation of SePat activity by Ac-CoA, a product of the Acs enzyme that also serves as a substrate for SePat-dependent acetylation, is likely a layer of metabolic control.

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Potentiometric and thermodynamic studies of [2 oxo 2h chromene 3 carbohydrazide] and its metal complexes

Potentiometric and thermodynamic studies of [2 oxo 2h chromene 3 carbohydrazide] and its metal complexes

The apparatus, general conditions and methods of calculation were the same as in previous work. The following mixtures (i), (ii) and (iii) were prepared and titrated potentiometrically at 298K against standard (0.004M) NaOH in 30% (by volume) ethanol-water mixture:

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The Determination of Surface Thermodynamic Properties of Nanoparticles by Thermal Analysis

The Determination of Surface Thermodynamic Properties of Nanoparticles by Thermal Analysis

The effect of dispersivity on thermodynamic and kinetic parameters of chemical reactions in nanodispersed systems is theoretically investigated. On the basis of the established theoretical dependences the new method of determination of surface thermodynamic properties of nanoparticles (surface enthalpy, surface entropy and surface energy) by thermal analysis (DTA or DSC) was developed. Three examples of calculation of surface properties of nanoparticles were pre- sented to prove the feasibility of this method.

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The density–salinity relation of standard seawater

The density–salinity relation of standard seawater

We performed a final calculation to estimate how signifi- cant the precise height positioning of the permanent magnet is, i.e. the distance from the coil. Two reasons for a change of the distance are conceivable. On the one hand, the posi- tion of the magnet (inside the float) or of the coil can change in the time between the calibration measurement obtained from water and the measurement obtained from seawater; the permanent magnet was fixed in the hollow float using wax (Millero, 1967). Density deviations that result from such position changes are minimized if, after each measurement obtained from seawater, a measurement obtained from wa- ter had also been carried out (a quasi-substitution measure- ment). On the other hand, the “lift-off” process, wherein the equilibrium current is determined by sight, is not the same for seawater and water in terms of speed (among other fac- tors). Density deviations that result from such dissimilarities are minimized, if, in additional to the “lift-off” current, the “drop-down” current had been determined in the opposite manner and both currents had been averaged for seawater and water, respectively. Or, if in the measurement obtained from seawater, the float was weighted with the aim to yield the same current as in the calibration measurement using wa- ter.

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The reactivity of the diethyl α acylphosphonates with the various α aminoesters: Synthesis and DFT (density functional theory) study

The reactivity of the diethyl α acylphosphonates with the various α aminoesters: Synthesis and DFT (density functional theory) study

Theoretically, we studied thermodynamically the possibility of the reaction between 1 and 2 possessing various substituents, using the calculation method DFT/B3LYP with the basis standard 6-31 G *, we determined under the standard conditions of temperature and pressure (298 k, et 1 atm (1 atm=101,325 Kpa)) changes in free energy ∆ rG, energy ∆ rE, and enthalpy ∆ rH. Table 1 presents their values obtained by the DFT/B3LYP method with the 6-31G* standard basis set. As shown in table 1, changes in free energy ∆ rG for reaction I are all negative, therefore, we have clearly shown that the reaction is possible and promotes thermodynamically. On the other hand, for reaction II, we observe that changes in free energy ∆ rG are all positive; this allowed us to say that the reaction II is not favored thermodynamically. We have also observed that the values of changes energy ∆ rE corresponding to a reaction I are more important than those of changes energy ∆ rE corresponding to a reaction II. This further confirms that the product 3 is the most stable and most majority. Moreover, Table 1 shows that reaction I with the values of change enthalpy ∆ rH negative is exothermic.

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The Equation of State of Biogas

The Equation of State of Biogas

It is necessary to determine the values of critical parameters of gases in the mixture for the calculation of the state behaviour of gases using the Redlich‑Kwong and Van der Waals equations. The basic physical properties of gases, which were also used in the calculation, are shown in Tab. I, from which it can be clearly seen that the critical parameters (especially critical temperature and pressure) of CH 4 and CO 2 are very different.

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