Orientation-dependent deformation behaviors of β single crystal micropillars in a metastable β titanium alloy

Abstract

The compressive deformation behaviors were investigated in metastable β Ti–7Mo–3Al–3Cr–3Nb alloy single crystal micropillars oriented to [011]β and [001]β. The study demonstrates that the metastable β titanium single crystal oriented to [001]β exhibits nonlinear elastic behavior with hysteresis, which is attributed to reverse β to α″ transformation. Furthermore, the yield strength of the single crystal oriented to [011]β is almost twice as of the single crystal oriented to [001]β, which is influenced by the different roles of ωath in both pillars due to differences in shear modulus G, in addition to being determined by the deformation mechanism at yielding. The continuous impedance to dislocation motion of ω and α″ phase in the pillar oriented to [011]β leads to a stable plastic flow behavior, but reverse β to ω phase transformation facilitating the formation of massive SIMα″ results in a sudden strain burst in the pillar oriented to [001]β. Finally, we find that the pillar oriented to [011]β is dominated by dislocation slip but SIMα″ occupies a dominant position in the pillar oriented to [001]β in the early deformation stage, which is same as predicted based on the martensitic transformation theory in metastable β titanium alloys.