EFFECT OF INTERFACIAL BONDING ON THE TOUGHENING OF AL2O3 NI CERAMIC-MATRIX COMPOSITES/

The main limitation to the toughening of the alpha-Al2O3/Ni composite is the poor bonding at the interface, which causes the nickel:particle s be pulled-out during crack propagation without obvious plastic defor mation. A proper control of oxygen content at the Al2O3-Ni interface c an promote wetting at the interface, and produce a mechanically interl ocked and chemically strengthened interface, causing most of the nicke l particles to be stretched to failure and to experience severe plasti c deformation during crack propagation in the composite. Fracture toug hness testing using a modified double cantilever beam method with in s itu observation of crack propagation in a scanning electron microscope shows that the composite with the strengthened interface has a more d esirable R-curve behaviour and a higher fracture toughness value than the normal composite.