SYNTHESIS OF NANOCRYSTALLINE ALUMINA METAL COMPOSITES BY ROOM-TEMPERATURE BALL-MILLING OF METAL-OXIDES AND ALUMINUM

The synthesis of nanometer-sized alpha-Al2O3-M composites (nanocomposites) is described for M = Fe, V, Cr, Mn, Co, Ni, Co, Zn, Nb, Mo, W, Si, and Fe alloys. The synthesis is performed by solid-state reduction reaction which occurs during room-temperature ball-milling of mixtures of a metal oxide (M(x)O(y)) and aluminum (Al2y/3). A complete reduction is reached for milling times of congruent-to 1.5 h in a planetary mill. The crystallite sizes of alumina and metal obtained, for powders processed in a vibratory mill, are in general about 10 nm.