SOLID-STATE REACTION IN NANOCRYSTALLINE FE SIC COMPOSITES PREPARED BYMECHANICAL ALLOYING/

Different solid-state reactions, i.e. Fe + SiC --> Fe3C + Fe(Si), and Fe + SiC --> Fe3Si + Fe2Si + C, were found in mechanically alloyed nan ocrystalline Fe/SiC composites induced by prolonged milling or heat tr eatment, respectively. The solid-state reaction between nanocrystallin e iron and SIC upon heating is greatly enhanced when compared with tha t between bulk iron and SiC. It is believed that the prolonged milling -induced reaction is related to the changed thermodynamics and kinetic s while the heat-treatment-induced reaction, completed during a short time, is attributable to the changed reaction kinetics.