Formation Conditions of Ti sub(2)O sub(3), MgTi sub(2)O sub(4), Mg sub(2)TiO sub(4), and MgAl sub(2)O sub(4) in Ti-Mg-Al Complex Deoxidation of Molten Iron

The relationships of the compounds in the Mg-Ti-Al-O system in equilibrium with molten iron are investigated at temperatures ranging from 1873 to 1973K, and the thermodynamic calculations are conducted in avoiding Al sub(2)O sub(3) or spinel MgAl sub(2)O sub(4) formation and for inclusion control. The equilibrium relations between the compounds (Mg sub(2)TiO sub(4), MgTi sub(2)O sub(4), or MgAl sub(2)O sub(4)) and the composition of solutes in steel are clarified. The conditions are shown that the transformation of the stable compound from Mg-Ti spinel to Mg-Al spinel occurs at Mg contents ranging from 1 to 10ppm by mass. It is also found, on the Mg-Ti spinel, the stable compound is transformed from inverse-spinel Mg sub(2)TiO sub(4) to normal-spinel MgTi sub(2)O sub(4) at Ti=about 60ppm by mass. In addition, the stable compound is transformed from MgTi sub(2)O sub(4) to Ti sub(2)O sub(3) at Ti=about 1000ppm by mass. The relationships of the compounds in the Mg-Ti-Al-O system in equilibrium with molten iron are clarified at temperatures ranging from 1873 to 1973K, and the thermodynamic calculations are conducted in avoiding Al sub(2)O sub(3) or spinel MgAl sub(2)O sub(4) formation and for inclusion control. It is shown that the equilibrium relations between those compounds and the composition of solutes in steel at 1973K.