Deformation behavior of metastable Ti-10V-2Fe-3Al alloy subjected to varying pre-strain levels: Mechanism and microstructural adaptations

This study examined the deformation behavior of the full β metastable Ti-10V-2Fe-3Al (Ti-1023) alloy under tensile loading and unloading conditions, with varying levels of pre-strain. The effects of tensile deformation on the microstructure were investigated using X-ray diffraction (XRD), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) techniques. The results indicated that there is nonlinear recovery in the unloading curve of metastable Ti-1023 alloy. With the increase of pre-strain, the degree of stress-induced martensite transformation (SIMT) increases, and a significant amount of residual α" phase persisted in the alloy following unloading, thereby inducing a gradual reduction in the recovery strain. The stress-induced martensite transformation (SIMT) occurs at the onset of the deformation process, with the α" martensite penetrating the β grain boundaries as it extends, and martensite with different orientations coordinates local strain through reorientation twins, which affects the variant selection of martensite. As the strain increases, the deformation twinning associated with plastic deformation, namely {130}< 310 > α" and {110}< 110 > α", also increases. Through the calculation of the complexity of atomic shuffling and the shear magnitude, the mechanism of the simultaneous observation of the {130}< 310 >_α" and its reciprocal {110}< 110 >_α" twinning mode during the deformation of metastable Ti-1023 alloy was elucidated.