A new CaO-Al2O3-Ce2O3-MgO-SiO2 tundish flux for rare earth steel has been presented in the current study based on the phase diagram and iso-activity diagram. The effect of Ce2O3 content and w(CaO)/w(Al2O3) on the melting temperature, viscosity, and crystalline phase was investigated. Results indicated that with the increasing Ce2O3 content and w(CaO)/w(Al2O3), the viscosity and melting temperature decreased, whereas the breaking temperature exhibited the opposite tendency. When the Ce2O3 content increased from 5 to 9 wt%, the crystalline phase began to precipitate. The Ce2O3 content further increases to 17 wt%, the crystalline phase changed from CaCeAl3O7 to CaCeAl3O7 and CeAlO3. The crystalline phase changed from CaCeAl3O7 to Ca3Al2O6, CaCeAl3O7, and MgO as the w(CaO)/w(Al2O3) increased from 0.9 to 1.3. The best range of the compositions of the low-reactivity tundish flux was w(CaO)/w(Al2O3) =1-1.3, MgO =5 wt%, SiO2 = 5 wt%, Ce2O3 = 0-10 wt%. The melting temperature was in the range of 1300-1320 degrees C, and the viscosity at 1500 degrees C was in the range of 0.18-0.45 Pa.s. The compositions were suitable for the development of sustainable metallurgy. [GRAPHICS] .
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