Excess aluminium effect on the composition and microstructure of Mo–Al alloys from aluminothermic reduction of MoO3

ABSTRACTThe effect of aluminium excess on the composition and microstructure of Mo–Al alloys from aluminothermic reduction of metallurgical-grade MoO3 was investigated. Aluminium excess ranged from 0 to 30% (in wt-%) with respect to the stoichiometric amount. The results showed that molybdenum yield increases for higher excess aluminium. The microstructure and composition of the alloys were investigated using scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and X-ray diffraction (XRD). The following phases were observed in the microstructures: Moss, Mo3Al, and Mo3Al8, besides particles of Al2O3. The results also showed that metallurgical-grade MoO3 leads to a product containing significant amounts of silicon.