Study on Phase Equilibria of CaO–SiO ₂ –La ₂ O ₃ System

The CaO–SiO 2 –La 2 O 3 system serves as a foundational La‐containing system for materials science, mineral processing, and metallurgical engineering. The phase diagram is indispensable for the thermodynamic database of multicomponent RE‐containing slag systems. In this paper, we employed high‐temperature equilibrium experiments and quenching methods, followed by EPMA and WDS to determine the morphology, composition, and type of equilibrium phases in the CaO–SiO 2 –La 2 O 3 system, respectively. Combining current work and literature data, the isothermal sections at 1600°C (including 3 three‐phase fields, 4 two‐phase fields, and a liquid phase field) and at 1500°C (including 3 three‐phase fields, 4 two‐phase fields, and a liquid phase field) were clarified. The liquidus projection of the CaO–SiO 2 –La 2 O 3 system with primary phase fields and Alkemade lines was obtained. Subsequently, the types and possible temperature ranges of the univariant lines and invariant points were discussed.