Microstructure development and fracture of in-situ reinforced Ti-8.5Al-1B-1Si

The conventional titanium alloys like Ti-6Al-4V are not suitable for application at high temperatures due to their metastable microstructure, high oxidation rates and loss of strength. In comparison, the α + α2 alloys have been studied for elevated temperature properties. Research on titanium alloys have of late included synthesis through the rapid solidification processing (RSP) route. The use of RSP allows the incorporation of B and Si in Ti alloys which allow for the in-situ nucleation of needle shaped borides and spherical silicides as dispersoids. This contrasts with the heterogeneous distribution of coarse dispersoids with conventional melting techniques. It has also been shown that these reinforcements lead to improvements in modulus, high temperature strength and creep resistance. Very limited information is presently available on the elevated temperature fracture properties of in-situ formed titanium composites. It is the object of this study to elucidate the micromechanisms of fracture under monotonic loading