New types of refractory materials need to be developed for designing the man-made ledge of the Hall-Heroult cell for aluminum electrolysis, which are currently constructed by frozen ledge.Magnesium aluminate spinel （MAS） as potential candidate materials was prepared by two-step sintering. The densification and grain growth of the MAS wereinvestigatedbytheArchimedes drainage method and scanning electron microscope （SEM）. All the specimens were corroded in aNa3AlF6-AlF3-CaF2-Al2O3bath to assess the corrosion resistance. The results show that a MAS material with a high relative density of 99.2% and ahomogeneous microstructure is achieved under two-step sintering conditions. The corrosion mechanisms of MAS inNa3AlF6-AlF3-CaF2-Al2O3 bathare mainly proposed by dissolution of MAS, formation of aluminum oxide, and diffusion of fluorides. The MAS prepared by two-step sintering exhibits good corrosion resistance to theNa3AlF6-AlF3-CaF2-Al2O3bath.
