THERMODYNAMIC PROPERTIES OF MELTS IN BINARY AND TERNARY SYSTEMS CONTAINING FE, MN, SI, TI, OR C

Abstract

The paper examines the application of the "analytical" Redlich-Kister-Muggianu model with a ternary contribution of -200 kJ/mol in predicting the thermodynamic properties of melts in the Fe–Mn(Ti)–Si, Fe–Mn–Ti, Mn–Si–Ti, Fe–Mn–C, Fe–Si–C, Mn–Si–C, Mn–Ti–C, Fe–Ti–C, and Si–Ti–C systems at 1873 K. It was established that in the the Fe–Mn–Si, Fe–Si–C, and Mn–Si–C systems, the minima of the mixing enthalpies correspond to the ternary melts. This is explained by the potential formation of ternary intermediate phases in these concentration ranges. Using both "geometric" and "analytical" models, the mixing enthalpies and component activities in the melts of these systems were estimated, based on analogous data from their binary subsystems. The obtained data allow predicting the behavior of alloys at high temperatures and optimizing their composition for specific applications. Special attention was paid to establishing accurate thermodynamic properties for the binary subsystems Fe–Ti, Ti–Si, Mn–Ti, and C–3d metal, using both literature data and the authors' calculations. A critical analysis of existing thermodynamic data yielded a new set of data for the Si–Ti, Fe–Ti, and Mn–Ti systems Component activities for Fe–Mn–Si melts were also calculated, revealing significant negative deviations from ideal solution behavior. Furthermore, silicon and titanium activities in the Si–Ti system melts were computed using liquidus coordinates from the phase diagram, based on Schröder’s equation and the regular solution model. It was shown that the calculated values of аSi and аТi derived from Schröder’s equation, aligned well with those from other models. The thermodynamic properties of M-C melts (M=3d-metal) were also investigated, an area that remains underexplored despite the critical role of carbon in metallurgy and materials science. The calculations showed that the minima of the enthalpies of mixing are observed in ternary melts of Fe–Mn–Si, Fe–Si–C, and Mn–Si–C systems suggest the formation of ternary intermediate phases. These results validate the reliability of the employed models and open new avenues for predicting the thermodynamic behavior of melts in metallurgy and materials science