In order to investigate the effective content of second phase Cu for enhanced fracture toughness and mechanical properties of Al2O3/Cu nanocomposite, materials with variation of 1 to 5 vol% Cu were studied. To obtain a fine, homogenously dispersed Cu phase in an Al2O3 matrix, hydrogen reduction of ball milled Al2O3 and CuO powder mixtures was preformed. Pulse electric current sintering (PECS) process was used to consolidate the composite powder, which was Al2O3 embedded with Cu particles formed by reduction of CuO. Relative densities of the sintered parts were over 99% by Archimedes' principle. Sintered specimens were analyzed by X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). Mechanical properties improved significantly with increasing Cu content. The increase of fracture toughness was explained by crack bridging and pull-out. The fracture strength was increased by the refinement of Al2O3 matrix grains through the nano-sized Cu dispersion.

Keywords: Nanocomposite, Rapid solidification, Mechanical properties