Thermodynamic modeling methods have been used for calculating the compositions of the condensed medium and gas phase forming upon heating of the oxides UO2, UO3, U3O8, and U4O9 at constant pressure (p = 0.1 MPa) in the temperature range 300–2000 K in an inert (Ar) or oxidative (O2) atmosphere. The stability of uranium oxides and the state of aggregation of the condensed medium have been studied as a function of temperature.

The possibility of formation of solid solutions in the subsolidus region was estimated for 15 binary eutectic systems, including systems with “degenerate” eutectics. Interrelations between the eutectic transition temperature and various physicochemical parameters of system components at the eutectic point are analyzed.

The values of ΔH°298, S°298, H°298–H°0, T, ΔH fus, and C p(T), as well as the temperature dependences of the Gibbs energy function, are calculated for Bi8O11 oxide by proven computational methods.

Thermodynamic modeling of the compositions of the condensed medium and the partial pressures of the gas-phase components forming on heating arsenic oxides in an inert atmosphere under isobaric conditions ( p = 9.8066 MPa) in the range from 300 K to the evaporation temperatures of these oxides has been performed.

Thermodynamic modeling of Al-Ce melts was performed at a total pressure p = 105 Pa in an argon atmosphere over the temperature and concentration ranges 1773–2373 K and 0 ≤ x Ce ≤ 1, respectively, corresponding to the liquid-phase region of the phase diagram of the system. The concentration and temperature dependences of the thermodynamic characteristics of the melts and the contents of melt components and gas phase components over the melts were calculated, the temperatures, enthalpies, and entropies of the liquid-gas transition were determined, and the phase diagram of the liquid-liquid + gas-gas transition was obtained.

Methods of thermodynamic simulation in view of existence of lithium atoms (Li 1 ), condensed and volatile Li 2 –Li 5 self-associates, Li 1 + , Li 2 + , and Li 3 + ions, and e -gas are used to calculate partial pressures of components of the gas phase over liquid lithium in the 1600–6000 K temperature range and the thermal characteristics of the system at 1600 and 6000 K.

The thermodynamic modeling methods are used to calculate the compositions of a condensed medium taking into account the existence of solid and liquid solutions of TiO2, TiO, Ti2O3, Ti3O5, and Ti4O7, as well as partial pressures of {TiO2}, {TiO}, {Ti}, {O2}, and {O} formed in heating initial titanium dioxide in an argon medium under a pressure of 9.8066 × 10−2 MPa in the temperature interval of 300–2485 K. The obtained results can be useful for the high-temperature synthesis of complex ceramics with the participation of titanium dioxide and for analysis of the composition of ceramics.

Thermodynamic modeling is used to determine the composition of condensed products of CuO heating in argon at a pressure of 9.8066 × 10 −2 MPa in the temperature range 300–1900 K. The formation of solid and liquid solutions with the participation of CuO, Cu 2 O, Cu 2 O 3 , Cu 3 O 2 , and Cu 4 O 3 is analyzed.

The paper presents the results of the thermodynamic modeling of the composition and state of aggregation of the condensed medium formed in a Bi2O3-Ar medium at 9.8066 × 10−2 MPa over the temperature range 300–1300 K. The possible presence of the Bi2O3, BiO, Bi2O5, and BiO2 oxides in the solid and liquid states was taken into account. Temperature-induced changes in the solid and liquid solution components (bismuth oxides in various states of aggregation) are discussed.

Thermodynamic modeling ( p = 9.8066 × 10 −2 MPa, T = 300–2500 K) is used to assess the thermal stability of MgB 12 , Mg 2 B 14 , MgB 6 , MgB 4 , and MgB 2 . The thermodynamic properties and functions of MgB 6 and Mg 2 B 14 are calculated for the first time. The results are compared with earlier reported data.

Variants of the formation of volatile Li-n (n = 2-5) clusters over a monatomic lithium melt and over a melt containing atoms and condensed Li-n (n = 2-5) clusters were studied using thermodynamic modeling methods. The gas phase composition and characteristics of lithium boiling at a total pressure of 9.8066 x 10(-2) MPa were analyzed.

Methods of Delta H-mix estimation on the basis of available information and the physicochemical parameters of alkali metal atoms were proposed and tested for the K-Na, Rb-Na, Cs-Na, Rb-K, Cs-Rb, and Cs-K melts.

The values of DeltaH(298)(0), S-298(0), enthalpy increment H-298(0) - H-0(0), DeltaH(ph.tr), and C-p(T) are estimated using computational methods. The temperature dependences of specific Gibbs energy for Na2K, Na2Cs, K2Cs, KCs, and hypothetic compound Na2Rb are calculated.

The validity of the hypothesis that melts of alkali metals (AMs) contain small self-associates (or clusters) [AM 2 ]‐[AM 5 ] was tested using the thermodynamic properties of volatile and condensed clusters of alkali metals [1] by computer experiments [2] in liquid alkali metal‐argon systems at a total pressure of 1 atm. The compositions of melts were described using a model of ideal solutions of interaction products [2]. The components of the solutions were atoms and various clusters; the components of the gas‐vapor phase were atoms, volatile clusters, alkali metal ions, and electron gas. The integral compositions of the initial systems were identical: 99 wt % of alkali metal and 1 wt % of argon. The components of the solutions and the gas phase for ten variants (variants 1‐10) of modeling are presented in Table 1. In this paper, we revealed model systems for which our calculated and published boiling points T b are in best agreement. For these systems, we analyzed the correspondence between the change in the enthalpy of boiling Δ H b and the saturation vapor pressure P s as functions of temperature according to the modeling and experimental data; we also calculated the compositions of model melts and the gas phase as functions of temperature. The calculated boiling points T b (AM) for variants 1‐10 and their comparison with published data [3‐7] are presented in Table 2 and Fig. 1. The calculated and published boiling points T b are seen to be in best ( ~0.5% ) agreement for variant 5 (the solution contains [AM 1 ], [AM 3 ], and [AM 5 ]; the gas phase contains AM 1 ‐AM 3 , AM 5 , alkali metal ions, and electron gas), and this is characteristic for all alkali metals. Table 3 shows that the calculated enthalpies of boiling Δ H b (AM) agree with published data [4, 5, 7]. Further, for alkali metals for variant 5, the saturation vapor pressures P s were calculated at various temperatures and the results obtained were compared with available data [3‐5]. An example of this is presented for a lithium system in Table 4. Similar comparisons were made for all alkali metals; the results are summarized in Table 5. Tables 4 and 5 show that the published P s values [3‐5] differ noticeably, the calculated P s values agree with the published values within the range of their difference between one another, and agreement is best between the calculated P s and P s according to Bystrov et al. [4]. Table 6 presents the coefficients of the expressions for P s (AM) as functions of temperature. Figure 2 demonstrates of the partial pressures of the i th components as functions of temperature by the example of the gas‐vapor phase over molten lithium. For all alkali metals, these data are given in Table 7. The compositions of model melts of alkali metals as functions of temperature are illustrated in Fig. 3 and Table 8. A detailed discussion of these data will be presented elsewhere. P i log

Optical metallography and electron microscopy were used to comparatively examine the structures of high-strength silumin produced by the conventional technology of smelting the charge in an electric furnace in air and by a new method of synthesis in a melt of halides. The classification of structural macrodefects observed in the castings produced by the conventional method is proposed; the dependence of the mechanical properties of castings on the defect concentration has been established. Advantages in favor of the new technology of synthesis of high-strength silumins, which ensures a modified structure and high mechanical properties of the material, are given.

The principal thermodynamic properties and the temperature dependences of reduced Gibbs energies were estimated using the available data, various suggestions, and calculation methods for real and hypothetical carbon compounds formed by the C-2-C-5 cluster molecules (clusterites) and the C-28, C-32, C-44, C-50, C-56, C-60, C-70, C-76, C-84, C-90, and C-94 fullerene molecules (fullerites).