A new beta titanium alloy system reinforced with superlattice intermetallic precipitates

A. J. Knowles; T. S. Jun; A. Bhowmik; N. G. Jones; T. B. Britton; F. Giuliani; H. J. Stone; D. Dye

Scripta Materialia 140 (2017) 71-75

Titanium alloys traditionally lack a nm-scale intermetallic precipitate that can be exploited for age-hardening from solid solution. Here such a strengthening concept is developed in the Ti-Fe-Mo system, with it being found that a high temperature β (bcc A2) single-phase field for homogenisation can be obtained, which following ageing (750 °C/80 h) precipitated B2 TiFe  <100 nm in size. The orientation relationship was found to be ⟨100⟩A2//⟨100⟩B2, {100}A2//{100}B2, with a misfit of −6.1%. The alloy was found to be very hard (HV0.5 = 6.4 GPa) and strong (σy, 0.2 = 1.9 GPa) with a density of 6.68 g cm−3. TEM observation and micropillar deformation showed that the precipitates resist dislocation cutting. DOI: https://doi.org/10.1016/j.scriptamat.2017.06.038