Influence of Sn on martensitic beta Ti alloys

The influence of Sn composition in Ti-17 at% Nb alloys is studied by cyclic tension and in-situ synchrotron X-ray diffraction. It is firstly found that Sn stabilizes β-phase and effectively suppresses the formation of ω-phase. Along with β-phase stability, we observe lowering of the austenite and martensite transformation temperature by ~100 K/at% and 88 K/at%, respectively. Increasing Sn decreases the martensitic transformation strain in Ti-Nb alloys by ~1.4%/at%, larger than that in Ti-Zr-Nb-Sn systems. The influence of Sn in martensitic Ti is anisotropic: causing larger reduction in lattice parameter b and higher decreases in elastic moduli of grain families that are aligned close to the b-axis. Finally, a {013}_{α ″}, {031}_α″,{122}_α″ and {211}_α″ quadruple texture was observed in martensitic Ti wire. At the early stage of deformation, detwinning quickly rotated {013}_α″ and {211}_α″ towards {031}_α″ and {122}_α″ components. After that, the strength of {031}_α″ continued to increase, while the strength of {122}_α″ texture was gradually decreased by dislocation slip as deformation continued.