Experimental Study on Phase Equilibria of CaO–Al 2 O 3 –Ce 2 O 3 System

High‐temperature phase diagram data for the CaO–Al 2 O 3 –Ce 2 O 3 system can provide necessary information for identifying new RE‑containing ceramic materials, the design and preparation of such materials, and the establishment of thermodynamic databases for related RE‐containing systems. Herein, we conduct high‐temperature equilibrium experiments followed by quenching at 1400°C, 1500°C, and 1600°C in a reducing atmosphere. Electron probe microanalysis, wavelength dispersive spectroscopy, and x‐ray diffraction were used to determine the morphology, composition, and phase identities of the equilibrium phases in the CaO–Al 2 O 3 –Ce 2 O 3 system, respectively. Based on the experimental results, isothermal sections at the three temperatures were determined. The liquidus projection was obtained, including univariant lines, invariant points, and Alkemade lines, and the corresponding invariant reactions and temperatures were clarified. The RE‐containing phases (Ce 2 O 3 , Al 2 O 3 ·Ce 2 O 3 , 11Al 2 O 3 ·Ce 2 O 3 , 2CaO·Al 2 O 3 ·Ce 2 O 3 , and 2CaO·3Al 2 O 3 ·Ce 2 O 3 ) in the system exhibit solid solubility to varying degrees. Calcium aluminates (3CaO·Al 2 O 3 and CaO·6Al 2 O 3 ) can also accommodate cerium to form solid solutions.