Effect of FeO Concentration on the Crystallization of High‐Temperature CaO–Al2O3–MgO–FeO Melts

Continuous cooling transformation ( CCT ) and time–temperature transformation ( TTT ) diagrams were plotted for CaO – Al 2 O 3 – MgO – FeO melts, and the morphology of the primary crystals formed was determined with a confocal laser scanning microscope ( CLSM ). When the CaO / Al 2 O 3 ratio is 1.0, the crystallization temperature and incubation time increase with increasing MgO content. The TTT curve at 7.5 mass% MgO has a “C” shape, which facilitates the formation of amorphous phases. However, increasing the FeO content accelerated the crystallization time and lowered the crystallization temperature. The solidified melt with an FeO content of less than 10 mass% was a combination of the C 3 MA 2 and C 5 A 3 phases; higher FeO content led to the formation of a secondary phase of Ca 2 FeAlO 5 and CA following the precipitation of the C 3 MA 2 primary phase. In addition, kinetic evaluation of the crystal growth with confocal micrographs indicated that the calculated crystal volume agreed well with the Johnson–Mehl–Avrami sigmoidal curve fit.