Al ₂ O ₃ –Ni Composites with High Strength and Fracture Toughness

Abstract

Al 2 O 3 –Ni composites were prepared by the reactive hot pressing of Al and NiO. The composites had a two‐phase, interpenetrating microstructure and contained ∼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–Al 2 O 3 interface), indicating a strong Ni–Al 2 O 3 bond.