The effect of β-phase condition on the tensile behaviour in a near-β Ti alloy produced by blended elemental powder metallurgy

In this study, a Ti-10V-3Fe-3Al alloy produced by the blended elemental powder metallurgy technique was subjected to two heat treatments at 675℃ and 625℃, resulting in lower β-phase stability and larger β-domain size in the sample heat treated at the higher temperature. The microstructural response to uniaxial tensile loading for the two conditions was investigated using a combination of optical microscopy, electron back-scattering diffraction and transmission electron microscopy. The observations indicate that a majority of deformation-induced products are formed in the vicinity of the fracture surface due to stress tri-axiality. Within this region, the 675℃ sample accommodated deformation via dominant {332}〈113〉 twinning, α″ martensite formation and limited {112}〈111〉 twinning. On the other hand, the sample with higher β-phase stability accommodated deformation via α″ martensite formation and perfect slip with reduced twinning activity.