Microstructure and properties of a novel titanium alloy Ti-6Al-2V-1.5Mo-0.5Zr-0.3Si manufactured by laser additive manufacturing

A novel α+β titanium alloy with multi-alloying addition and low-cost is designed from Ti-6Al-4V. In order to maintain the same [Al]eq and [Mo]eq, the Mo and Zr were added into the alloy instead of V, and the nominal composition of this novel alloy is determined as Ti-6Al-2V-1.5Mo-0.5Zr-0.3Si with a spot of Si added. In this study, a plate of the novel alloy was manufactured by laser additive manufacturing (LAM). The macrostructure, microstructure, compositions, microhardness and room temperature tensile properties of as-deposited alloy were investigated. The results show that the macrostructure of the novel alloy contains large columnar grains and small columnar grains. Compared to the reference alloy Ti-6Al-4V manufactured with the same process, the novel alloy had much finer basket-weave microstructure. This novel alloy, solid-solute with alloying elements Mo, Zr and Si, has higher microhardness and better combination of strength and plasticity compared to Ti-6Al-4V.