In this study, titanium–niobium (Ti-Nb) alloy samples containing β, α′′, ω and α′ were used to investigate the effect of each phase on the mechanical properties. The results show that the content of each phase affects the shape of the tensile curve. When the fraction of ω phase is relatively large, the tensile curve exhibits obvious upper yield point and lower yield point. However, the fraction of α′′ phase is relatively large; the tensile curve has a single peak yield stage. A small amount of α′ phase can significantly improve the yield strength, however, the elongation decreased significantly. In addition, some ω phase surrounded in α′′ matrix was also observed, and it can be inferred that the micro-crack may first appear at the incoherent ω/α′′ interface under the application of external stress.

In this study, the mechanism of {332}<113> twinning formation in cold-rolled Ti-35Nb-2Ta-3Zr-O (wt %) alloy was investigated based on the Taylor-Bishop-Hill theory. The experimental data of crystal orientation in the rolling bite zone was obtained via electron back-scattered diffraction (EBSD). The deformation energy of {332}<113> twinning in the propagation stage was calculated using data from EBSD in terms of the Hall-Petch-type relation. The calculation results revealed that the mechanism of {332}<113> twinning formation in β-type Ti-35Nb-2Ta-3Zr-O (wt %) alloy contained two valid models, namely the shear-shuffle model and α″-assisted twinning model. This can help to clarify the mechanism of {332}<113> twinning formation further.