The mechanical behavior of layered brazed metal/ceramic composites

Brazing as a method of joining thin metal and ceramic plates to form a layered composite for structural applications is examined. The constituents are Ti-6Al-4V alloy sheets and alumina thin plates and the brazing alloy is 63 wt% Ag, 1.75 Ti and bal. Cu active braze alloy. The interfacial shear strength of the joint is relatively high, which makes it attractive for structural applications. A model Ti alloy/alumina bilayer and laminate joined by active brazing was evaluated for its basic mechanical behavior. The bilayer structure tested under bending exhibited improved properties when the alumina layer was under compression during loading. In that case, a combination of the high compressive strength of ceramics, the high toughness of metals and the high shear strength of the interface are causes of the improved mechanical properties when compared with those of the monolithic metal. Using composite beam theory, the properties of bilayers were evaluated for design purposes and, in particular, the interfacial shear strength. The laminated structure tested under bending showed reduced strength but improved undamaged stiffness when compared with the metal constituent. (C) 1998 Elsevier Science B.V.