Revealing the martensitic variant selection in metastable beta titanium alloy Ti–10V–2Fe–3Al under heterogeneous deformation

As an important deformation mode for the mechanical responses of titanium (Ti) alloys, the martensitic transformation has earned enormous interest, for example, the variant selection, under macro uniaxial stress by tension or compression. However, the variant selection under small-scale deformation with a complex loading condition was rarely reported. In the present study, the small-scale deformation of metastable beta Ti alloy was investigated using nanoindentation combined with the transmission electron microscope (TEM) observation. Different martensitic variants were detected under the complex strain/stress field given by the indenter in the single titanium crystal, which was well interpreted by the Schmid factor (SF) and interaction work (IW) criterion, with the assistance of finite element (FE) simulation. The same prediction given by SF and IW comes from the truth that SF for simple shear is a special case of the IW criterion.