T. V. Kulikova

Thermophysical properties of Ti-5Al-5V-5Mo-3Cr-1Zr titanium alloy

The thermophysical properties of the Ti-5Al-5V-5Mo-3Cr-1Zr titanium alloy in a wide range of temperatures from room temperature to 1000°C have been studied by the methods of differential scanning calorimetry, the laser flash method, and dilatometry. The obtained data on heat capacity, thermal diffusivity, and thermal expansion have been used for calculating coefficient of thermal conductivity. The sequence and temperatures of structural transformations during heating of the alloy have been established. It has been shown that the studied alloy possesses a coefficient of thermal conductivity that is 3.5–4 times smaller than that of pure titanium.

Thermophysical and electrical properties of equiatomic CuZr alloy

Differential scanning calorimetry, laser flash technique, dilatometry, and a method based on a rotating magnetic field were used to study for the first time thermophysical and electrical properties of the Cu50Zr50 equiatomic alloy in the quenched state and after annealing at temperatures ranging from room temperature to 1100 K. The thermal conductivity coefficient was calculated using the results of heat capacity, thermal diffusivity, and density measurements. The sequence and temperatures of structural transformations in the quenched Cu50Zr50 alloy were determined during alloy heating. The electron component of thermal conductivity was estimated using the Wiedemann–Franz–Lorentz law. This law was found to be satisfied well for the quenched sample at temperatures above 600 K and for the annealed sample at temperatures beginning from 900 K. As the temperature decreases, the lattice contribution increases. This fact indicates the marked effect of strong chemical interaction between copper and zirconium on the heat- and electrotransport processes.

Thermodynamic modeling of the reaction of polychlorinated biphenyls with sodium methoxide

Thermochemical parameters, like standard enthalpy of formation (ΔH2980), enthalpy increment from 0 to 298 K (H2980 - H00), standard heat capacity (Cp2980) and its temperature dependence [Cp(T)], and entropy (S2980), were calculated for the gaseous methoxy derivatives formed from polychlotinated biphenyl (PCB) congeners. Thermodynamic modeling and the HSC software were used to evaluate the reactivity of PCB congeners toward sodium methoxide in DMSO, and the calculation results were compared with experimental data.

Thermodynamic properties of melts based on the Al-Sm system

The equilibrium composition and thermodynamic characteristics of melts based on the Al-Sm system were studied by thermodynamic modeling using the ideal solution model of reaction products over the whole range of compositions 0 ≤ xAl ≤ 1 in argon at a total pressure of 1 atm and temperatures from 1873 to 2100 K.

Thermal Properties of CuGa2 Phase in Inert Atmosphere

Thermal decomposition of copper digallide was studied using experimental (thermal analysis) and theoretical (thermodynamic modeling) methods. The temperatures of CuGa2 incongruent melting are in satisfactory agreement between experimental and calculated values. Small differences with the phase diagram can be explained by minor non-stoichiometry of the alloy samples. The experimental studies of thermal diffusivity and thermal expansion of CuGa2 were performed in the temperature range 298-500 K. The heat conductivity coefficient was further calculated using literary data concerning the density and heat capacity of the copper digallide.

The interaction of low- and medium-chlorinated biphenyls with sodium methoxide with the account for thermodynamic modeling

The interaction of low- and medium-chlorinated congeners of polychlorinated biphenyls of the Trikhlorbifenil technical mixture with sodium methoxide in dimethylsulfoxide has been studied by means of experimental and calculation methods. Thermodynamic modeling of the process has revealed exclusive formation of the methoxy derivatives in the studied process. whereas the experiment has revealed the formation of methoxy, hydroxy, and methoxy(hydroxy) derivatives of congeners of polychlorinated biphenyls.

Effect of Titanium Additions on the Thermophysical Properties of Glass-Forming Cu 50 Zr 50 Alloy

Differential scanning calorimetry, laser flash method, and dilatometry were used to study the thermophysical properties of quenched Cu50Zr50–xTix (x = 0, 2, 4, 6, 8) alloys in the temperature range from room temperature to 1100 K. Data obtained on the heat capacity, thermal diffusivity, and density have been used to calculate the coefficient of thermal conductivity. Temperatures corresponding to the stability of martensite CuZr phase, its eutectoid decomposition, and formation in Cu50Zr50–xTix alloys with different Ti contents upon heating have been determined. It has been found that the thermal diffusivity and thermal conductivity of the studied alloys are low and a typical of metallic systems. As the titanium content increases, the coefficients of thermal conductivity and thermal diffusivity vary slightly. It has been shown that the low values of thermophysical characteristics correspond to the better capability of amorphization and can be a criterion for the glass-forming ability of Cu–Zr-based alloys.

Peculiarities of the martensitic transformation in (Cu0.5Zr0.5)100−xAlx glass-forming alloys

ABSTRACT We systematically study peculiarities of the martensitic transformation (MT) in glass-forming alloys focusing on the one. We obtain that an addition of aluminum to the binary alloy leads to a decrease of both the martensite and the austenite start temperatures. The former reaches the room temperature area for the alloy. The martensitic transition proceeds as two-stage transformation of the CuZr B2 phase in two monoclinic phases (P21/m and Cm). The proceeding of the MT depends on annealing temperature. It is also shown that fast quenching of the samples in liquid nitrogen leads to the same MT as observed at slow cooling.

Optimization of the reaction of polychlorobiphenyls with a binucleophile by thermodynamic modeling

The reaction of congeners of Sovol commercial mixture of polychlorinated biphenyls with 2-aminoethanol in the presence of potassium hydroxide was studied. The results of thermodynamic modeling show that only hydroxy derivatives of polychlorobiphenyls should be formed. The optimum conditions for complete dechlorination of the congeners were determined: 1 atm, 170°С, molar ratio polychlorobiphenyls: 2-aminoethanol: potassium hydroxide = 1: 8: 6. The experimental data obtained using the theoretically chosen initial conditions for the reaction of polychlorobiphenyls with 2-aminoethanol show that the conversion increases from 82 to 96%.

Crystallization kinetics of rapidly quenched Cu50Zr50 and Cu46Zr46Al8 glass-forming alloys

We studied the crystallization processes, the structure and thermal properties of amorphous alloys Cu50Zr50 and Cu46Zr46Al8 in a wide temperature range. Comparative study of the crystallization kinetics of these amorphous alloys was carried out for the first time using multivariate non-linear regression. It was found that mechanisms of the crystallization of studied metallic glasses are substantially different. The binary alloy is crystallized by branched reaction complex in four steps. For the ternary system was proposed two-step kinetic model of the crystallization process with consecutive reactions. The values of the total energy of activation for each crystallization stage reach to Cu50Zr50: E1 (345.2 kJ/mol); E2 (307.9 kJ/mol), E3 (281.1 kJ/mol), E4 (259.51 kJ/mol) and Cu46Zr46Al8: E1 (350.7 kJ/mol); E2 (150.4 kJ/mol).