Blade Fabrication Process for Titanium Matrix Composites

Abstract

Continuous fiber reinforced titanium matrix composites (TMC) are attractive as one of the potential structural materials for aerospace applications, because of their high specific strength and stiffness. However, TMC parts are not yet put into practical use due to their limited damage tolerance and an enormous production cost resulting from process limitation requiring preliminary forming and elaborate tooling for consolidation. In order to reduce the production cost, superplastic TMC sheets (SiC/Ti-4.5Al-3V-2Mo-2Fe) were developed, and deformation properties, and cavitation behavior were investigated. The blade-shaped model was formed successfully out of the newly developed TMC sheet by means of Argon-gas-pressure forming technique. However, in order to reduce the defects that were observed in fiber/matrix interface of the deformed TMC, the tensile flow stresses in TMC sheet during deformation should be minimized. In this study a diaphragm forming method, whereby a TMC sheet is forced against the form tool surface by pressure acting on a driving sheet, was adopted to reduce the tensile stress generated in TMC sheet during superplastic forming of blade-shaped models. As a result, no defects were observed by an optical microscope in the TMC deformed by diaphragm forming method. Diffusion bonding techniques to attach the root blocks to the deformed TMC sheet and the reduction of the blade-fabrication cost are also discussed.