Effect of Zr, Sn and Al Additions on Deformation Mode and Beta Phase Stability of Metastable Beta Ti Alloys

Abstract

The relation between deformation mode and β phase stability was investigated using Ti-16V and Ti-7Cr base alloys doped with Sn, Zr and Al as ternary or quaternary additions. Sn and Al additions change the dominant deformation mode from (332) twinning in the binary alloys to deformation induced martensitic transformation, which is related to the suppression of athermal ω phase transformation by the addition of these elements. The deformation induced martensite has orthorhombic structure (a”) or hexagonal structure (a’) depending on the alloying element. On the other hand, Zr addition has no significant influence on deformation mode and athermal ω phase transformation, and thus the dominant deformation mode of Zr added alloys is (332) twinning identical to the binary alloys. Discrepancy in deformation mode observed in metastable β titanium alloys can be explained reasonably by considering the present results on the effect of Sn, Zr and AI on the deformation mode. © 1991, The Iron and Steel Institute of Japan. All rights reserved.