Application and assessment of aluminium deoxidation equilibria in liquid steel using various formalisms based on some statistical thermodynamic models

Aluminium, is being added to liquid steel in a wide concentration range. Wagner's interaction parameter formalism (WIPF) has been successfully used to fit the experimental data reported by several researchers at 1873 K in a low Al content range, however, a huge variation was observed beyond a few wt.% of Al. In the present work, to calculate Al-O equilibria, besides (i) WIPF, (ii) Lupis and Elliot's formalism has been recalculated and (iii) Unified interaction parameter formalism (UIPF) has been developed for the first time on a wt.% scale. Thermodynamic analysis has also been carried out to account for short range order in Fe-Al-O system using (iv) associate model while (v) modified quasi-chemical model (MQM) is summarized from the literature. The present thermodynamic analysis assesses the suitability of various formalisms based on regular and quasichemical model for a wide Al concentration range in liquid steel.