Titanium-manganites of LaLi₂TiMnO₆ and LaNa₂TiMnO₆ were synthesized by the methods of ceramic technology from the oxides of lanthanum, titanium (IV), manganese (III), and the carbonates of lithium and sodium. The types of their syngony and the parameters of their gratings were determined radiographically. The isobaric heat capacities of titanium-manganites were measured with experimental calorimetry in the range of 298.15–673 K. It was found that on the dependence curve of heat capacity versus temperature of C°_p~f(T), for LaLi₂TiMnO₆ at 348 K and 598 K, and LaNa₂TiMnO₆ at 348 K, there are abnormal jumps in heat capacity, probably related to phase transitions of the second kind. Taking into account the temperatures of the phase transitions, the equations of the temperature dependence of the heat capacity of titanium-manganites were derived. Their standard entropies were calculated by the ion increments method. Temperature dependences of the thermodynamic functions of S°(T), H°(T)-H°(298.15), and Φ^xx(T) were calculated using the experimental data on heat capacities and the calculated values of the standard entropies. The standard heat capacities of the studied compounds were calculated by the independent methods of ion increments and Debye, the values of which were in satisfactory agreement with the experimental data. The standard enthalpy of the formation of LaLi₂TiMnO₆ and LaNa₂TiMnO₆ was calculated according to the methodology developed by the authors. The conducted electrophysical studies determined the nature of the second-order phase transition and the semiconductor features of their conductivity. Thus, all the above-mentioned data on the experimental and calculated studies of the temperature dependence of heat capacity, the thermodynamic functions to determine a standard enthalpy of formation of LaLi₂TiMnO₆ and LaNa₂TiMnO₆, and the investigation of their electrical properties are absolutely new, and they have no analogues.

This article describes a new quantitative evaluation method for the degree of dissociation of a compound depending on the curvature of the liquidus line curve. The main point of this method was to determine the specific expressions for dissociation parameters according to the mathematical model of the crystallization line of the compound on the phase diagram. This was based on generally accepted thermodynamic relations. Empirically, it has now been established that for many types of phase equilibria, a common feature is the presence of a correlation dependence between the ratios of the real Gibbs energy of the distribution of components to its ideal component. The osmotic coefficient of Bjerrum–Guggenheim was used as a measure of the deviation of the system from ideality. This coefficient can be in an analytical form depending on the temperature and composition of the phases. The obtained correlation dependence of the osmotic coefficient of Bjerrum–Guggenheim on the ratio of the activity of the liquid and solid phase has been used to develop a mathematical apparatus to analytically describe the lines and surfaces of the crystallization phases. Accordingly, a single analytical basis, as a universal dependence of the modified Schröder–Le Chatelier equation, has been applied. Based on this equation, the conditions have been defined to develop an equilibrium method with which to calculate the thermal dissociation of chemical compounds. The principle of this method has been examined based on the two-component iron-titanium system. The numerical results of the degree of dissociation of the congruent Fe₂Ti compound have been obtained using the Gibbs energy of the dissociation reaction and the reaction constant. However, it has been found that the degree of dissociation in the compound Fe₂Ti was 0.04%. Demonstrative material for the behavior of the osmotic coefficient of Bjerrum–Guggenheim under boundary conditions has been presented as an assessment criterion of melt structures. The diagrams of the Φi function of the crystallizing phases near the melting temperature of congruently melting compounds (Tm.) have been mathematically studied. Thus, this study demonstrates that Φ${}_{A_m{B}_n}^{\prime }$ diagrams tended to zero and approached the melting temperature of the compound ${\mathrm{T}}_{m,A_m{B}_n}^{}$, i.e., above the melting temperature of this compound Φ${}_{A_m{B}_n}^{\prime }$→∞; then,$\ln x_{A_m{B}_n}$→0, and, as a result, $x_{A_m{B}_n}$→1.

A priority direction of ferrous metallurgy development is to increase in output of the high quality metal and metal products of new assortment. One of the methods to improve a quality of steels is to involve of complex alloys based on aluminum, silicon, manganese, etc. for their output. They are necessary as deoxidizing agents and alloying additives. This paper considers the possibility of the thermodynamic substantiation of the aluminum solubility in the ferrosilicon-aluminum complex alloy (FeSiAl) on the basis of their phase diagrams using the osmotic coefficient of the Bjerrum-Guggenheim. Methodology used is based on the theoretical studies of the phase equilibria using the Bjerrum-Guggenheim concept. It includes a set of computer programs in C# language (C sharp) designed to evaluate a deviation scope of properties of a real system from the ideal one. Criterion for evaluation is an osmotic coefficient of the Bjerrum-Guggenheim. The pattern of change in an osmotic coefficient of the Bjerrum-Guggenheim on the ratio of activity of components in the ideal liquid and solid phases (positive Фi 1) under the boundary forming conditions of crystallization regions of phases related to the melting ferrosilicon-aluminum processes is a direct proof of the possibility to use it as a metal reducing agent. The calculated mathematical dependences of the osmotic coefficient of the Bjerrum-Guggenheim permit us to determine the crystallization temperature of the ferrosilicon-aluminum alloy. The alloying process with rich aluminum content is observed at this temperature. The dependence diagrams of an osmotic coefficient of the Bjerrum-Guggenheim of a crystallizing component on the ratio of its activity in the liquid and solid phases demonstrated that a temperature rise leads to strong negative deviations in silicon properties, and thus to its good mixability in the melt with iron and aluminum. Compositions of silicon-aluminum alloys with high aluminum content in the ferrosilicon-aluminum complex alloy (FeSiAl) were determined on the basis of their phase diagrams using the osmotic coefficient of the Bjerrum-Guggenheim with iron content of 12-37%, aluminum 20-25% and silicon 68-38%. The received theoretical results permit to determine conditions which give the maximum possible aluminum assimilation with the ferrosilicon-aluminum melts supplied from the high-ash coal in the melting process of this metal in the ore-thermal furnaces. Thus it is a direct method to develop the output technology of the complex alloys.

Method for studying the phase equilibria of a titanium-based metal system from the standpoint of the Bjerrum–Guggenheim concept was proposed and a mathematical model was created that can be used to obtain low-percentage grades of ferrotitanium using silicon-aluminum reducing agents. In this work, binary systems Ti–Fe, Ti–Si and Ti–Al, simulating the main composition of ferrotitanium, are studied from a thermodynamic point of view. To establish the correlation dependences of the Bjerrum–Guggenheim coefficient in these binary systems, data were obtained on the nature of interparticle interaction in melts with the derivation of analytical expressions for the liquidus and solidus lines, and experimental data were also processed for the equilibrium compositions of the liquid and solid phases from the melting temperature of iron to stable eutectics. Two types of a generalized mathematical expression as the modified Le Chatelier–Shreder equation are proposed to analytically describe the liquidus and solidus lines of phase diagrams for a whole class of systems.

The study investigates the technology of direct Cr alloying of steel in an induction furnace using Cr-containing oxide raw materials and an FeAlSiCa metallothermic reducing agent under atmospheric conditions. The experimental design included four charge variants: scrap-based, DRI-based, A-series (50% scrap/50% DRI), and B-series (75% scrap/25% DRI). For A-series and B-series, the FeAlSiCa content was varied from the baseline value to reduced levels of −10% and −20%. The results demonstrate that Cr recovery strongly depends on the metallic component of the charge. The highest Cr recovery (up to 83%) was consistently achieved for the DRI-based charge, while mixed charges showed intermediate values depending on the DRI fraction and reducer amount. Reduction in FeAlSiCa content led to a decrease in Si transfer to steel, but was accompanied by lower Cr recovery. The produced steels were characterized by a uniform distribution of alloying elements, low impurity levels (S, P < 0.03%), and the formation of a dense, non-disintegrating slag. The results confirm that direct Cr alloying in an induction furnace can be effectively implemented under atmospheric conditions without vacuum or protective gas atmosphere, while the presence of DRI plays a key role in enhancing Cr assimilation.