Design and Microstructural Characterization of High Performance β-Metastable Titanium Alloys Presenting Simultaneous TRIP and TWIP Effects

beta-Ti alloys with plasticity driven by dislocation glide suffer from a lack of work hardening, which is most of the time a major drawback. In this work, first attempts on the design of a new family of Ti alloys with improved strain hardening rate have been performed on two specific alloys. Those alloys, namely Ti-12Mo and Ti-9Mo-6W (wt.%), have been chosen by extending the “d-electron alloy design method” initially proposed by Morinaga et al. for the design of superelastic alloys. These new beta-metastable Ti grades were chosen as good candidates for the improvement of the mechanical properties of as-quenched beta phase thanks to expected competition between two deformation mechanisms : TRIP and TWIP effects. Mechanical tests reveal a work hardening rate never reached before by Ti alloys, while various characterization techniques revealed the mechanical activation of twinning and of alpha’’ and omega phases