Abstract

Mechanical properties of oxide based materials could be improved by nanocomposite processing. To investigate optimum route for fabrication of nanocomposite enabling mass production, high energy ball milling and Pulse Electric Current Sintering (PECS) were adopted. By high energy ball milling, the Al_2O_3-based composite powder with dispersed Cu grains below 20 nm in diameter was successfully synthesized. The PECS method as a new process for powder densification has merits of improved sinterability and short sintering time at lower temperature than conventional sintering process. The relative densities of the Al_2O_3-5vol%Cu composites sintered at 1250°C and 1300°C with holding temperature of 900°C were 95.4% and 95.7% respectively. Microstructures revealed that the composite consisted of the homogeneous and very fine grains of Al_2O_3 and Cu with diameters less than 40 nm and 20 nm respectively The composite exhibited enhanced toughness compared with monolithic Al_2O_3. The influence of the Cu content upon fracture toughness was discussed in terms of microstructural characteristics.