Microstructure and Mechanical Property of Ti-5Al-2.5Sn/Ti-6Al-4V Dissimilar Titanium Alloys Integrally Fabricated by Selective Laser Melting

Metallic structural components made from dissimilar titanium alloys are playing important roles in high-end industries such as aerospace and aviation. In this paper, a Ti-5Al-2.5Sn/Ti-6Al-4V dissimilar titanium alloy material was additively manufactured by the selective laser melting (SLM) process. Interface characteristics, microstructure, and mechanical properties of the SLM-deposited samples before and after complete annealing treatment were researched to provide some technical basics for the integral fabrication of dissimilar titanium alloy components. The results demonstrated that a defect-free metallurgical bonded interface with a ~ 70-mu m-wide element inter-diffusion region could be obtained between the Ti-5Al-2.5Sn and Ti-6Al-4V layers under both the as-deposited and the complete annealing states. The interfacial bonding strength between the dissimilar titanium alloys was always higher than the strength of the Ti-5Al-2.5Sn layers. Microstructure evolution and element inter-diffusion mechanisms of the SLM-produced Ti-5Al-2.5Sn/Ti-6Al-4V samples were also revealed and related to the change in mechanical properties.