Effects of Zr Content on the Microstructures and Tensile Properties of Ti-3Al-8V-6Cr-4Mo-xZr Alloys

The microstructural evolution and tensile properties of Ti-3Al-8V-6Cr-4Mo-xZr（x = 0,2,4 and 6） titanium alloys were investigated.The precipitated phases and tensile fracture morphologies were observed using scanning electron microscopy and transmission electron microscopy.Experimental results show that the presence of trace impurity Si and the addition of Zr induce the formation of（TiZr）_6Si_3 silicides.The quantity of silicides increases with Zr content increasing.The dispersed silicides refined the grain size of β Zr-containing alloys,and the grain size decreases significantly with Zr content increasing.Accompanying these microstructural changes,the strength of the alloys is enhanced gradually with the increase of Zr content,which is attributed to the combination of precipitation strengthening and grain refinement.