Effect of martensite on {332} twinning formation in a metastable beta titanium alloy

{332}_β twinning and stress-induced martensite transformation are two important deformation mechanisms in the metastable beta titanium alloys, which can effectively strengthen the titanium alloys via twinning induced plasticity (TWIP) and transformation induced martensite (TRIP) effect, respectively. For a TWIP + TRIP metastable beta titanium alloy, {332}_β twinning and stress-induced martensite can co-exist to improve the mechanical behaviors. However, the underlying mechanism for the co-existence of {332}_β twinning and stress-induced martensite is not clear. Here we employed a model metastable beta titanium alloy Ti-2Al-9.2Mo-2Fe (wt%) to reveal the correlation between {332}_β twinning and stress-induced martensite. The deformation gradient analysis and magnitude of shuffling needed for twining were utilized to reveal the relationship between {332} twinning and stress-induced martensite. As a result, we found that {332} twinning is a product of the reverse bcc to orthorhombic phase transformation. Such mechanism leads to a strong correlation between {332} twinning and stress-induced martensite, causing the {332} twinning combining stress-induced martensite in the present alloy.