Influence of aging treatment on microstructure and mechanical properties of a new high strength TB17 titanium alloy

Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and X-Ray Diffraction(XRD)were employed to investigate the influence of heat treatment conditions on microstructure and mechanical properties of a new high strength TB17 titanium alloy at aging temperature from 530°C to 620°C. The results showed that the aging temperature had a significant influence on microstructures and mechanical properties of the alloy. At aging temperature of 530 °C, the existence of lamellar secondary α phase with a size of 40nm resulted in high tensile strength above 1500MPa and acceptable elongation of 6%. The secondary α phases had a great effect on the mechanical properties of TB17 titanium alloy, i.e. the fine acicular secondary α phase contributed to quasi-cleavage fracture, while the coarse α phases lead to the ductile fracture. Finer secondary α phase could provide more α/β phase interface, which could act as the site of micro-crack nucleation and hinder the dislocation movement inside the titanium alloy, thus, a higher strength could be obtained for the TB17 titanium alloy.