Ce‐Containing Species‐Induced Structural Evolution and Thermophysical Responses in CaO–Al 2 O 3 ‐Based Refining Slags

To clarify the structural role of CeO 2 in CaO–Al 2 O 3 ‐based refining slag for rare‐earth microalloying high‐Al steel, the structural evolution and thermophysical properties of slags containing 0–18.21 wt.% CeO 2 were investigated. The results reveal a dual structural effect associated with Ce‐containing species. Ce‐containing species act as network modifiers, weakening aluminate network connectivity and promoting the transformation of highly polymerized units into less polymerized species, thereby facilitating structural rearrangement. Simultaneously, Ce‐containing species are associated with higher‐coordinated Al–O environments and Ce‐related local coordination, while SEM–EDS reveals a tendency toward Ce–Ca–Al association during solidification, suggesting enhanced short‐range structural ordering and coordination stability. Accordingly, viscosity decreases with increasing CeO 2 addition, reaching an approximately 33% reduction at 1650 °C with 18.21 wt.% CeO 2 . In contrast, density, surface tension, and melting temperature increased by approximately 19%, 28%, and 78 °C, respectively, owing to enhanced local packing efficiency and structural stability. A composition–structure–property relationship is proposed, suggesting that viscosity is predominantly associated with long‐range network connectivity, whereas density, surface tension, and melting behavior are influenced by short‐range local coordination. These findings provide insight into the structural evolution of rare‐earth‐containing refining slags and offer a useful basis for understanding the composition–structure–property design of rare‐earth metallurgical slags.