Spark plasma sintering technique for reaction sintering of Al2O3/Ni nanocomposite and its mechanical properties

Al2O3/Ni nanocomposites were prepared by spark plasma sintering (SPS) using reaction sintering method and the mechanical properties of the obtained nanocomposites are reported. The starting materials of Al2O3-NiO solid solution were synthesized from aluminum sulfate and nickel sulfate. These Al2O3-NiO powders were changed into Al2O3 and Ni phases during sintering process. The obtained nanocomposites showed high relative densities (>98%). SEM micrographs showed homogeneously dispersed Ni grains in the matrix. The 3-point strength and the fracture toughness of the composites significantly improved from 450 MPa in the monolithic alpha-Al2O3 to 766 MPa in the 10 mol% (2.8 vol.%) Ni nanocomposite and from 3.7 to 5.6 MPa m(1/2) in 13 mol% (3.7 vol.%) Ni nanocomposite. On the other hand, Young's modulus and Vickers hardness of the nanocomposites were mostly same as those of the monolithic alpha-Al2O3. (C) 2006 Elsevier Ltd and Techna Group S.r.l. All rights reserved.