Using a mix of Al2O3 powders to which other reinforcing materials such as: ZrO2, SIC, Ni and Ti were added up to 10 wt%, and the combination of conventional techniques known as milling-pressing-sintering, several composite samples were fabricated. The microstructures of the composites reinforced with (Ni or Ti) examined in the scanning electron microscope showed a slight metallic network formed between the alumina grains. The action of several mechanisms such as crack bridging, crack deflection and microcraeldng seems to be the cause of the improvement in the fracture toughness of the composites with respect to that of monolithic alumina. The experimental values of elastic modulus and hardness of the composites diminished, although, on the other hand, the compressive and flexural fracture strengths were increased when alumina was reinforced with the materials studied here.

Keywords: Alumina composites; Fracture toughness; Reinforcements; Metal networks