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

A Ti-6Al-4V/sigma (SM 1240) composite prepared by diffusion bonding has been studied in the as received condition, using Auger electron spectroscopy, transmission electron energy loss spectroscopy, and scanning electron microscopy. The SiC based sigma fibre has a tungsten core, and 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 matrix and formed TiB needles. Carbon was detected in the TiB(x) layer and was present in elemental free form. A continuous SiO2 + carbon layer was detected at the SiC/carbon layer interface. Analysis of in situ fracture composite surfaces in an Auger spectrometer has shown that the tensile failure was initiated within the carbon layer or at the TiB(x)/matrix interface. An oxide layer detected at the TiB(x)/matrix interface influenced the fracture behaviour of the composite.