An in-situ study of microstructural evolution and mechanical property in an (α+α'+β) Ti-Al-V-Fe alloy

In this study, a novel α+α'+β dual-phase titanium alloy designated T422, was developed through Fe alloying of Ti-6Al-4V, exhibiting excellent comprehensive mechanical properties. The quasi-static tensile strength of the alloy reaches 1100 MPa, with an elongation after fracture of 25.1 %, and a maximum strain hardening rate of 7.7 GPa. In-situ electron backscatter diffraction (EBSD) was employed to track the microstructural evolution of the α+α'+β titanium alloy during tensile deformation. By combining slip trace analysis and martensite crystallographic calculations, the deformation mechanisms at each stage were analyzed. The results indicate that martensite reorientation dominates the early deformation stage, resulting in a high strain hardening rate. While in the middle and late stages, mechanisms such as slip, twinning in α_p phase, and secondary martensitic transformation within the β matrix contribute to enhanced elongation.