REDUCTION OF MAGNETITE BY ALUMINUM - A DISPLACEMENT REACTION INDUCED BY MECHANICAL ALLOYING

The displacement reaction between aluminum and magnetite during mechanical alloying has been investigated. Explosive solidstate reaction occurs in a wide range of compositions as evidenced by the sudden temperature rise of the grinding vial. X-ray diffraction and scanning electron microscopy have been used to investigate the reaction products. The reaction takes place in three steps: (i) composition-dependent incubation period; (ii) high-temperature combustion during which a nonuniform mixture of final and intermediate phases forms; and (iii) gradual phase transformation and particle refinement upon continued milling.