A phase diagram of the FeO-SrO-BaO system

At present, the refinement technology using ligatures containing alkaline earth metals, in particular barium and strontium, is being increasingly introduced into the production of steels and alloys. The construction of a phase diagram of the FeO-SrO-BaO system is of interest from the point of view of the analysis of phase equilibria realized in an oxide system conjugated to a molten metal. In the course of this work, thermodynamic modeling of phase equilibria was carried out, followed by calculation of the coordinates of the liquidus and solidus lines for phase diagrams of the FeO-SrO, FeO-BaO, and SrO-BaO oxide systems. Using the obtained data on binary oxide systems, we performed thermodynamic modeling of phase equilibria with the subsequent construction of a projection of the liquidus surface for the phase diagram of the ternary oxide system FeO-SrO-BaO. For each of the systems, the energy parameters of the theory of subregular ionic solutions, which describes the activities of the components of the oxide melt, were determined. The energy parameter of the theory of regular ionic solutions, which describes the activities of the components of the solid solution of oxides |SrO, BaO|s.s, was also determined. The phase diagrams of the FeO-SrO and FeO-BaO systems are eutectic type diagrams with one eutectic point with coordinates of 18.00 mol. % SrO and 1060 °C; 31.58 mol. % BaO and 1066 °C, respectively. The SrO-BaO system is characterized by unlimited solubility of the components, both in the liquid and in the solid state. For the phase diagram of the FeO-SrO-BaO system, an extensive equilibrium region of the oxide melt with the solid solution of oxides |SrO, BaO|s.s, was noted.