Microstructure and mechanical properties of Al2O3/Cu–O composites fabricated by pressureless infiltration technique

Al2O3/Cu–O composites were fabricated using pressureless infiltration of a copper–oxygen alloy into alumina preforms containing different volume fraction of open porosity. Pressureless infiltration of all alumina preforms was obtained for copper–oxygen alloy containing 3.2 wt% of oxygen. Al2O3/Cu–O composites exhibit high strength and fracture toughness, e.g. KIc about 8.4 MPa m−2 for samples containing approximately 29 vol% of metal phase. SEM micrographs of fractured surfaces showed deformed metal ligaments which demonstrated that crack bridging by plastic deformation of the metal phase is one of the toughening mechanisms for Al2O3/Cu–O composites. XRD analysis showed the presence of α-Al2O3, Cu and Cu2O only.