Effect of Microstructures on Mechanical Properties of Ti-6.5Al-2Sn-4Zr-4Mo-1W-0.2Si Alloy

The tensile properties at both room temperature and 550 degrees C are investigated in Ti-6.5Al-2Sn-4Zr-4Mo-1W-0.2Si with three typical microstructures, which are lamellar, bimodal, and equiaxed microstructures. The results show that the yield and ultimate tensile strengths decrease while the ductility increases as the volume fraction of primary a phase increases at both temperatures. The above phenomena result from the decrease in the beta transformed microstructure, which consists of fine a and beta lamellae with high-density alpha/beta interfaces blocking dislocation slipping. The yield and ultimate tensile strengths at 550 degrees C are lower than that at room temperature, and the ductility at 550 degrees C is higher than that at room temperature, both of which are attributed to the activity of multislipping systems at high temperature.