Al2O3-Ni composites with high strength and fracture toughness

Al2O3-Ni composites were prepared by the reactive hot pressing of Al and NiO. The composites had a two-phase, interpenetrating microstructure and contained similar to 35 vol% Ni. They exhibited an impressively high combination of strength and toughness at room temperature; the four-point bending strength was in excess of 600 MPa with a fracture toughness of more than 12 MPa.m(1/2). Examination of fracture surfaces showed that Ni ligaments underwent ductile deformation during fracture. SEM analysis revealed knife-edged Ni ligaments with a limited amount of debonding around their periphery (i.e., at the Ni-Al2O3 interface), indicating a strong Ni-Al2O3 bond.