Highly toughened nickel dispersed aluminabased nanocomposites were fabricated using our developed soaking method, based on our previously proposed toughening mechanism of nanocomposites. Commercially available galumina agglomerate with high porosity was used as a starting material. Nickel nitrate solution was penetrated into the nanopores of the galumina agglomerate using this new technique. The aluminanickel composite pow der with aalumina seeds was then sintered using a pulse electric current sintering technique. To disperse disloca tions generated around the nanoparticles into alumina grains, the sintered materials were annealed. The results showed that the maximum fracture toughness was 7.6 MPam 1/2 , which was about two times higher than that of dense alumina.[ Received November 18, 2004; Accepted November 26, 2004] Keywords : Nanocomposites, Alumina, Nickel, Fracture toughness, Soaking method, Toughening mechanism

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