Effect of Silicon on Mechanical Properties of Ti-6Al-2Zr- 1Mo-1V Alloy

The influence of Si content on the mechanical properties of Ti-6Al-2Zr-1Mo-1V titanium alloy at room temperature and 500℃ was studied. The fracture morphologies and microstructures were analyzed by scanning electron microscope (SEM) and transmission electronic microscope (TEM). The nucleation and growth of silicide were related to the mechanical properties. The results show that the tensile strength and high-temperature strengthening performance are improved when 0.04 wt%~0.14 wt% Si is added to the Ti-6Al-2Zr-1Mo-1V alloy; the plasticity is less changed; the impact toughness and plane strain fracture toughness are decreased. An alternating tendency from ductile fracture to brittle fracture can be found with the addition of Si, the radial region is enlarged, and the area of fibrous region and shear lip is minified. When the content of Si is less than 0.09 wt%, the Si elements are dissolved in α and β phase, and solid solution strengthening mechanism dominates. The silicide precipitates along the phase boundary when the content of Si reaches 0.14 wt%, which leads to a combination of solution strengthening and precipitation strengthening.