Equilibrium Between Yttrium and Oxygen in Molten Iron

Rare earth is an important additive to improve the comprehensive properties of steel products. To precisely control the amount of rare earth in the molten steel and rare earth inclusionsInclusions is a fundamental issue that has not been effectively solved due to the lack of accurate thermodynamic data. The equilibrium between yttriumYttrium and oxygen in the liquid ironIron was investigated using pure Y2O3 crucibles for smelting experiments, and accurate thermodynamic data were obtained in the range of 1600–1700 °C. The results show that the deoxygenation product of yttriumYttrium was Y2O3 and the equilibrium constant of the reaction Y2O3(s) = 2[Y] + 3[O] can be expressed as follows: \( \log K_{{\text{Y}}} \left( {K_{{\text{Y}}} = \, a_{{\text{Y}}}^{2} a_{O}^{3} /a_{{{\text{Y}}_{2} {\text{O}}_{3} }} } \right) = - 60065/T + 18.92\quad 1600 - 1700\;^\circ {\text{C}} \) While the deoxidation productDeoxidation product, \(K^{\prime}_{{\text{Y}}} ( = [\% {\text{Y}}]^{2} [\% {\text{O}}]^{3} )\) , was expressed as follows: \( \begin{aligned} \log K_{{\text{Y}}}^{\prime } & = \log K_{{\text{Y}}} - ( - 19591/{\text{T}} + 1.72) \times (3[\% {\text{Y}}] + 11.1[\% {\text{O}}]) \\ & \quad 0.006 < [\% {\text{Y}}] < 0.21 \end{aligned} \) By the use of the interaction parameterInteraction parameter \(e_{{\text{O}}}^{{\text{Y}}} = - 19591/T + 1.72\) .