Ternary system Al2O3-MgO-CaO: I, primary phase field of crystallization ofspinel in the subsystem MgAl2O4-CaAl4O7-CaO-MgO

Using a novel experimental procedure in the field of ceramics/materials sci ence that is based on the precise microanalysis (scanning electron microsco py, coupled with wavelength-dispersive spectroscopy) of the phases that are present in equilibrated specimens, the solid-state compatibility relations in the subsystem MgAl2O4-CaAl4O7-CaO-MgO and the melting relationships in the subsystems MgAl2O4-CaAl2O4-MgO and MgAl2O4-CaAl2O4-CaAl4O7 were establi shed. The primary phase field of crystallization of spinel in the above-men tioned subsystem, MgAl2O4-CaAl4O7-CaO-MgO, was determined subsequently. The temperature, composition, and character of the ternary invariant points of the subsystem were established, and the ranges of the solid solutions in p ericlase, spinel, monocalcium aluminate, and dicalcium aluminate also were studied and determined, up to 1725 degrees C.