Design of titanium alloys by additive manufacturing: A critical review

Additive manufacturing (AM) is an innovative technology that creates objects with a complex geometry layer-by-layer, and it has rapidly prospered in manufacturing metallic parts for structural and functional applications. Recent literatures have investigated the effect of different AM technologies on the microstructure evolution of titanium alloys. However, metal AM has mostly been regarded only as a shaping technology for near-net-shape manufacturing. A huge advantage of AM in alloy design and treatments has been largely overlooked at the present time. In this paper, we systematically reviewed the interaction of AM processes and different Ti-alloys, as well as the possible ways for mechanical property enhancements. On the one hand, the complex thermal histories caused by AM influence the phase transformation of Ti-alloys. On the other hand, the unique thermal and processing features of AM provide ways and opportunities to design new Ti-alloys with unachievable microstructures and properties by conventional methods. The aim of this paper is thus to provide a new perspective on the relationship between the AM process and alloy design, which is to consider AM as an irreplaceable material treating and design method. Only an integrated consideration of both AM process and alloy design can successfully achieve materials with superior properties for applications in the future industries.