Phase Diagram Study of the Nd₂O₃-SiO₂-FeO-Fe₂O₃ System at 1773 K in Air

The phase diagram information of the Nd₂O₃-SiO₂-FeO-Fe₂O₃ system is basic for the design and development of slag for recycling NdFeB magnets by pyrometallurgical processes. The equilibria phase relations of the Nd₂O₃-SiO₂-FeO-Fe₂O₃ system were investigated at 1773 K in air using a high-temperature isothermal equilibration technique followed by quenching. Seven two-phase equilibria regions and seven three-phase equilibria regions were observed by X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS) analysis of quenched samples. Ternary compounds Nd_9.33Si_6−xFe_xO_26-δ and Nd_0.67Si_0.13Fe_0.2O_δ were found. The 1773 K isothermal section was constructed for the Nd₂O₃-SiO₂-FeO-Fe₂O₃ system.