Synthesis of Nanocrystalline Alumina–Metal Composites by Room‐Temperature Ball‐Milling of Metal Oxides and Aluminum

The synthesis of nanometer‐sized α‐Al 2 O 3 −M composites (nanocomposites) is described for M = Fe, V, Cr, Mn, Co, Ni, Cu, 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 (Al 2y/3 ). A complete reduction is reached for milling times of ≅ 1.5 h in a planetary mill. The crystallite sizes of alumina and metal obatined, for powders processed in a vibratory mill, are in general about 10 nm.