Microstructural evolution and fracture toughness of Al2O3/Ti composites

The effect of different additions of a metal (Ti) on the microstructure and fracture toughness of Al2O3-based ceramics, as well as the establishment of a route for their processing was analyzed in this study. The samples were prepared by means of mechanical milling and pressureless sintering in an argon atmosphere. Due to the fact of working with very small sizes of powders of both the metal and ceramic, it was possible to reach in sintered products greater values of densification than 95% of their relative density. Measurements of fracture toughness (K-IC) evaluated by the fracture indentation method, indicate that this mechanical property had improved with some additions of Ti in the composite, for example K-IC for pure alumina processed under the conditions of this study was 3.0 MPa . m(1/2), whereas, K-IC for the composite with 3 vol % Ti was 4.1 MPa . m(1/2). The microstructure observed in a scanning electron microscopy shows the formation of small and fine metallic interpenetrating networks in the ceramic matrix, that improve in their formation with an increases of Ti in the composite.