The effects of Nb content on microstructure and fracture behavior of near α titanium alloys

Abstract The microstructure and fracture behavior of as-cast Ti-1100 alloys with different contents of Nb were systematically investigated. The results demonstrate that the Nb element added to titanium alloys changes the lattice parameters of α phase. Microstructural observations indicate an obvious reduction in the prior β grain size, α -laths spacing, as well as the thickness of β phase, with the increase of Nb content. It is also observed that Nb addition promotes the formation of ternary (TiZr) 6 Si 3 (S 2 type) silicides. The fracture toughness K IC of the alloy increases with increasing content of Nb element, which is primarily attributed to the improved propensity for crack-tip tortuousity caused by the fracture behaviors of the α / β colonies. The fracture morphologies of these alloys reveal cleavage fracture mode.