EFFECT OF FIBER COATING ON THE MECHANICAL-BEHAVIOR OF SIC FIBER-REINFORCED TITANIUM ALUMINIDE COMPOSITES

The effects of fiber surface coatings on the mechanical behavior and damage mechanisms of SCS-6 fiber-reinforced titanium aluminide matrix composites have been studied. Two different coating layers are used as model material: a brittle TiB2 and a ductile Ag/Ta duplex layer. The role of the coating layer on the interfacial reaction, interfacial properties, and mechanical behavior of the composites was characterized. Results indicate that both TiB2 and Ag/Ta are effective diffusion barriers in preventing fiber/matrix interfacial reactions during composite consolidation. However, the deformation mechanisms and crack propagation characteristics in these two coated composites are quite different. The criteria for selecting an improved interlayer to tailor a strong and tough fiber-reinforced titanium aluminide matrix composite are also discussed.