Deoxidation equilibrium of calcium in liquid iron

The previous literature thermodynamic values for deoxidation equilibrium relation shows a loop of reciprocal Omega shape in the figure which shows the relation between calcium and oxygen dissolved in liquid iron. This means one concentration of calcium corresponds to two or more concentration of oxygen and vice versa. This discrepancy between predicted and measured results is due to an incomplete expression of the activities of dissolved calcium and oxygen in current literature. It causes by use of only Ist order interaction parameters to express the activities of calcium and oxygen. In the present work, the deoxidation equilibrium of calcium was studied to develop values for the Ist and 2nd order interaction parameters including cross products too. As the result, the thermodynamic values of calcium deoxidation obtained was in good agreement with the observed values.