Characterisation of sigma SiC fibre/titanium alloy MMCs fabricated by plasma spraying and foil/fibre methods

Preliminary characterisation has been carried out of titanium alloy/SiC fibre composites manufactured by plasma spraying, using a new 'spray-wind' process which is particularly suitable for producing multi-ply MMC rings. A comparison of spray-wind material has been made with material of similar composition produced by the existing technique of plasma spraying of monotapes, and with material produced by a more conventional solid state route termed foil-fibre-foil processing. Examination of fibres extracted from unconsolidated composites has suggested that significant fibre damage may have occurred by liquid-metal impact during plasma spraying. This damage reduced the fibre uniaxial tensile strength, bend strain to failure and Weibull moduli. Further damage resulted during consolidation. Fibre/matrix interfacial reactions in as-sprayed and consolidated spray-nind material were generally similar to those for vacuum plasma sprayed, and subsequently consolidated monotapes, respectively. Vacuum hot pressing of vacuum plasma sprayed Ti-6Al-4V matrix/1140+ C-coated SiC fibre monotapes formed a similar to 1 mu m fibre/matrix reaction zone consisting primarily of TiC