Effect of primary α phase fraction on deformation mechanism of Ti-1023 alloy at room temperature

The fraction and morphology of α phase have important effects on the mechanical properties and deformation mechanism of Ti-1023 alloy. Here, the tensile stress-strain curves and deformation mechanisms with the fraction of α phase are discussed in detail. As α phase fraction decreases from 67.5 % to 12.6 %, there is a negative correlation coefficient between the yield strength and α phase volume fraction of Ti-1023 alloy, and its fitting equation is obtained. When the fraction of α phase is decreased to 12.6 %, the elongation and ultimate tensile strength of the alloy are 31.09 % and 845.52 MPa, as well as a transition from single to double yielding phenomenon, which is caused by stress-induced martensitic transformation (SIMT). When the fraction of α phase is high, the deformation mechanism is dominated by dislocation slip and mechanical twinning of the α phase. When the fraction of α phase is low, the deformation mechanism is dominated by mechanical twinning of the β matrix and stress-induced martensitic transformation (SIMT). The relationship between α phase fraction and deformation mechanism and mechanical properties of Ti-1023 in α+β dual phase region is studied, which provides a template to guide the development of comprehensive mechanical properties of metastable β titanium alloy in α+β dual phase region.