Phase equilibria in the Fe-Sr-Ba-O-С system

In this work, thermodynamic modeling of phase equilibria in the Fe-Sr-Ba-O-C system is carried out. The surfaces of solubility of the components in the liquid metal are plotted. The effect of temperature (1550 and 1600 °C) and carbon content ([C] = 0; 0.1 wt. %) on the structure of the solubility surface of metal components (SSSM) has been studied. In carrying out the calculations, we used the theory of subregular ionic solutions to calculate the activities of the components of the oxide melt, the theory of regular ionic solutions to calculate the activity of the components of the solid solution of oxides, and the first-order interaction parameters to calculate the activities of the components of the metal melt. Thermodynamic analysis showed that the most probable products of the deoxidation reaction of the melt with barium and strontium are solid solutions |SrO, BaO|. The calculations show that barium practically does not participate in the deoxidation process (the content of BaO in the solid solution ranges from 10-2 to 10-3, and in the oxide melt - hundredths). The low solubility of strontium and, especially, barium in liquid iron predetermines the low deoxidizing and high modifying ability of the Ba-Sr complex. In the future, it is necessary to conduct a study of the behaviour of these elements in combination with calcium, aluminium and silicon.