REDUCTION AND SINTERING OF A NICKEL-DISPERSED-ALUMINA COMPOSITE AND ITS PROPERTIES

High-density nickel-dispersed-alumina (Al2O3/nickel) composites with s uperior mechanical properties were obtained by the hydrogen reduction and the hot pressing of alumina-nickel oxide (Al2O3/NiO) mixed powders . The mixtures were prepared by using NiO or nickel nitrate (Ni(NO3)(2 ) . nH(2)O) as a dispersion source of nickel metal. Microstructural in vestigations of the composite fabricated using nitrate powder revealed that fine nickel particles, approximate to 100 nm in diameter, disper sed homogeneously at the matrix grain boundaries, forming the intergra nular nanocomposite. High strength (>1 GPa) and high-temperature hardn ess were registered for the composite that contained a small amount of nickel dispersion. The ferromagnetic properties of nickel, such as hi gh coercive force, were observed, because of the fine magnetic dispers ions, which indicates a functional value of structural composites.