SYNTHESIS OF NOVEL NIOBIUM ALUMINIDE-BASED COMPOSITES

A reactive sintering process has been used to produce almost fully den se composites with interpenetrating networks of NbAl3 and Al2O3. The p rocess involves the reaction synthesis of niobium aluminides and Al2O3 from compacts of intensively milled aluminum and Nb2O5 powder mixture s. During carefully controlled heating under and inert atmosphere, the oxide reduction by aluminium to form niobium aluminides and Al2O3 pro ceeds at temperatures below the melting point of aluminium. At tempera tures of >1000 degrees C, the reaction-formed niobium aluminides and A l2O3 sinter. The present paper discusses processing parameters, such a s attrition milling, the heating cycle, and the metal:ceramic ratio in the starting mixture, that control microstructure development and mec hanical properties.