The effects of Zr contents on microstructure and properties of laser additive manufactured Ti-6.5Al-3.5Mo-0.3Si-xZr alloys

A new type of Ti-6.5Al-3.5Mo-0.3Si-xZr (x = 1.5, 2.5, 3.5, 4.5 wt%) titanium alloys developed on TC11 alloy (x = 1.5) with different Zr contents were fabricated by laser additive manufacturing process in order to enhance the mechanical properties. Grain morphology and microstructure were systematically investigated. The results demonstrate that the addition of Zr element dramatically refines the grains of the titanium alloys by offering heterogeneous nucleate sites and controlling grain growth during subsequent thermal cycles. And the latter is the main influencing factor. Meanwhile, the addition of Zr element in the alloys does not affect their microstructures, which with similar α lamellar thickness. And the microhardness and compressive strength of the alloys continuously increase with the increase of Zr contents.