1873K에서 고농도 티타늄을 함유한 Fe-Ti 용탕에서 티타늄과 산소의 열역학적 거동 해석

Abstract

Titanium forms a large amount of stable oxides and all oxides have large negative free energies of formation. Titanium is very reactive for O, and each equilibrium titanium oxide phase would change with Ti content in liquid Fe–Ti alloy phase. Deoxidation behavior has been reported in Fe-Ti alloys with a maximum Ti of 50 mass%. However, due to incomplete separation of Ti oxides, the Fe-Ti alloy contained the high oxygen content. On the other hand, the equilibrium oxygen partial pressure for conducting the experiment in the Fe-Ti system with Ti-rich region is very low. In this study, the oxygen concentration and the equilibrium oxide phase were measured by using Fe-Ti alloy with 10~70 mass% of Ti at 1873K. A MgO crucible charged with pre-melted alloy and TiO (purity 99.9%) was set in an induction furnace. The sample was melted under deoxidized Ar-3%H2 of 500 ml/min and the oxygen partial pressure at starting stage was measured as about ~10(-22) atm. By EBSD, the observed oxide phase in Fe-Ti alloy was TiO which was reported as stable oxide phase in Fe-Ti alloy with high concentration of Ti. It was shown that the present model successfully reproduced available experimental data for the Ti deoxidation equilibria.