Titanium matrix reinforced composites produced by H.I.P. of plasma sprayed preforms

The present work has been focussed on the fabrication of long fibre reinforced titanium composites by hot isostatic pressing (HIP) of plasma sprayed preforms. Silicon carbide long fibers were used together with two different metallic matrices, the first being a Ti-6Al-2Sn-4Zr-2Mo alloy and the second a Ti-4.5Al-3V-2Mo-2Fe alloy also named SP700. All the spraying trials were performed by using a Controlled Atmosphere Plasma Spraying equipment (CAPS), allowing deposition processes also in the high pressure range. After optimisation of the plasma spraying procedure, on the basis of results obtained with preliminary spraying trials carried out according to a DOE methodology composite multilayers were fabricated by HIP with different comibinations for the process parameters temperature/time/applied pressure, in the range 850-940°C, 30-45 min, 1200 bar They were then qualified by microstructural investigations and tensile testing at room and high temperature (up to 600°C). Obtained results are reported and discussed with particular reference to differences evidenced for the two titanium matrices.