Influence of Sn on martensitic beta Ti alloys

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2019-01, Vol.743 (C), p.764-772
• Main Authors: Cai, S., Wang, L., Schaffer, J.E., Gao, J., Ren, Y.
• Format: Article
• Language: English
• Subjects: Alloy systems; Beta phase; Deformation mechanisms; Detwinning; Dislocations; Martensite; Martensitic Ti; Martensitic transformations; MATERIALS SCIENCE; Modulus of elasticity; Phase stability; Phase transformation; Synchrotron; Synchrotron radiation; Texture; Titanium base alloys; Transformation temperature; X-ray diffraction; Zirconium
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2018.11.095

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.