CHEMISTRY EFFECTS ON INTERFACE MICROSTRUCTURE AND REACTION IN TITANIUM-BASED COMPOSITES

The effects of fibre and matrix chemistry on the interface microstructure and stability of Ti-based composites were investigated using Sigma SiC monofilaments as reinforcements and different titanium alloys, namely Ti-6Al-4V, Ti-1100 and Super-alpha2, as matrices. Both monomatrix composites and 'hybrid' composites were processed by a solid-state diffusion-bonding technique, respectively incorporating either one type of matrix or different matrices into a single sample. Interface microstructures and reaction were analysed with respect to the reactivities of the interfaces and the diffusivities of the relevant elements involved. When the coated fibre was used, TiB needles were found in Ti-6Al-4V and Ti-1100 matrices but not in the Super-alpha2 matrix. The reaction rate was slower in a more heavily alloyed matrix. The question of optimizing interface microstructure through matrix chemistry and hybrid composites is addressed.