Fabrication, microstructure and mechanical properties of Al2O3/Ni nanocomposites by a chemical method

Al2O3/Ni nanocomposites were prepared by a chemical method and hot-pressing technique using Al(NO)3·9H2O and NiO as the starting materials. At 1450 °C the composites can achieve >98% theoretical density after hot-pressing. Microstructural results revealed that Ni grains were uniformly dispersed in the Al2O3 matrix, some fine Ni grains of ∼100 nm were entrapped within Al2O3 grains, some Ni grains of 100–300 nm were dispersed at the grain boundary, forming intra/inter-type nanocomposite. The three-point bending strength and the fracture toughness of the dense Al2O3 composite increased by 26 and 79%, respectively, with the addition Ni content. The strengthening and toughening mechanisms of the composite with respect to the microstructure are analyzed.