Influence of metallic properties on the fracture characteristics of Al₂O₃/Ti/Ni‐laminated composites

Abstract

The mutual confinement of ceramics and metals in laminated composites tends to change the original properties of ceramics and metals. In this study, two kinds of laminated composites, Al 2 O 3 /Ti and Al 2 O 3 /Ti/Ni, were prepared. Three-point bending experiments revealed that Al 2 O 3 /Ti underwent brittle fracture after elastic deformation. The fracture morphology analysis revealed that the Ti in Al 2 O 3 /Ti became brittle due to the formation of columnar crystals. The temperature gradient perpendicular to the direction of laminations during preparation was responsible for the formation of columnar crystals. The force-displacement curves of the Al 2 O 3 /Ti/Ni combine the properties of elastic deformation of ceramics and plastic deformation of metals. The reason why the Al 2 O 3 /Ti/Ni did not fracture completely in the bending experiments is that Ni maintained the toughness, and there is a good interfacial bond among Al 2 O 3 , Ti, and Ni. The indentation crack analysis revealed that cracks have long transverse propagation and short longitudinal propagation in both laminated composites. Finite element analysis revealed that this was due to compressive stress in the Al 2 O 3 layer and tensile stress in the metal layer. This compressive stress consumes the crack energy in the longitudinal direction and stops the crack in the metal layer. The brittle to ductile gradient transition among Al 2 O 3 , Ti, and Ni, combined with the guidance of crack propagation direction by the interfacial layer, enhances the ability of Al 2 O 3 /Ti/Ni to resist damage.