AS RECEIVED TI-6AI-4V SIGMA/SIC FIBER-COMPOSITE/

A Ti-6Al-4V/sigma (SM 1240) composite prepared by diffusion bonding ha s been studied in the as received condition, using Auger electron spec troscopy, transmission electron energy loss spectroscopy, and scanning electron microscopy. The SiC based sigma fibre has a tungsten core, a nd a duplex coating of carbon (adjacent to the SiC deposit) and TiB(x) . It is shown that boron from the TiB(x) layer diffused into the matri x and formed TiB needles. Carbon was detected in the TiB(x) layer and was present in elemental free form. A continuous SiO2 + carbon layer w as detected at the SiC/carbon layer interface. Analysis of in situ fra cture composite surfaces in an Auger spectrometer has shown that the t ensile failure was initiated within the carbon layer or at the TiB(x)/ matrix interface. An oxide layer detected at the TiB(x)/matrix interfa ce influenced the fracture behaviour of the composite.