Charpy impact behaviour of Sigma fibre reinforced titanium composites

Charpy impact behaviour of SIC fibre reinforced titanium composites (TMCs) has been examined at a range of temperatures on specimens with fibres orien tated longitudinally [0](8) and transversely [90](8) to the impact directio n. Corresponding monolithic alloys have also been studied. Although monolit hic Ti -6Al-4V has the superior 'bend' strength at room temperature? Timeta l 834 is superior at the operating temperatures of gas-turbine components. The TMCs follow the same trends as the monolithic alloys, but their impact strengths are inferior to the monolithic alloys by an order of magnitude. T his is attributed to the ion impact strength of the SIC fibres, which domin ates in [0](8) specimens, and the low strength of the fibre/matrix interfac e, which dominates in [90](8) specimens. For [0](8) specimens, Ti-6-4 reinf orced with carbon coated SIC fibres (Sigma SM1140+) has consistently superi or impact strength compared with the other three TMCs. For [90](8) specimen s, Timetal 834 reinforced with TiBx/carbon coated SiC fibres (SM1240) exhib its the best impart strength at intermediate temperatures. MST/4560.