Anisotropic Deformation and Damage Behavior of Brittle-Ductile Laminated Composites in Bending at High Temperature

Abstract

Brittle-ductile alternate laminates with strong interfaces, Al2O3-Ti3SiC2 multilayer composites, are fabricated by hot-pressing thin Al2O3 tapes coated with a mixture of titanium, silicon, and graphite powders at 1550 C. The damage evolution and subcritical growth of macrocracks in these novel composites are investigated by three-point bending tests at high temperatures. By comparing the mechanical response in different loading directions, the anisotropic mechanical properties of the laminated beams are revealed. The experimental results show that, with the stress redistribution and the neutral axis shift toward the compressive surface during the creep damage, increased cracks occur in the Al2O3 layers and slowly extend toward the neutral axis without brittle fracture. It is demonstrated that the creep damage of the Al2O3-Ti3SiC2-laminated composites in bending is governed by a combination of stress relaxation in Ti3SiC2 layers and subcritical crack growth in Al2O3 layers. This result implies that controllable subcritical crack growth and crack arrest in brittle ceramics could be accomplished by means of a ductile-brittle joined structure. This prediction is confirmed by using a bending test on an aluminum beam with a glass coating bonded on the side surface.