Science | 2021
In situ design of advanced titanium alloy with concentration modulations by additive manufacturing
Abstract
Description Fine-scale strengthening swirls Creatively combining different alloys using additive manufacturing methods has the potential to produce materials with interesting properties. Zhang et al. use laser powder bed fusion to combine small amounts of 316L stainless steel into Ti64 titanium alloy. This process creates an alloy with a distinctive microstructure that retains high strength while substantially improving ductility. The design strategy should be useful for improving mechanical properties in other alloy system as well. —BG Fine-scale concentration modulation created by combining 316L stainless steel with Ti64 titanium alloy improves mechanical properties. Additive manufacturing is a revolutionary technology that offers a different pathway for material processing and design. However, innovations in either new materials or new processing technologies can seldom be successful without a synergistic combination. We demonstrate an in situ design approach to make alloys spatially modulated in concentration by using laser-powder bed fusion. We show that the partial homogenization of two dissimilar alloy melts—Ti-6Al-4V and a small amount of 316L stainless steel—allows us to produce micrometer-scale concentration modulations of the elements that are contained in 316L in the Ti-6Al-4V matrix. The corresponding phase stability modulation creates a fine scale–modulated β + α′ dual-phase microstructure that exhibits a progressive transformation-induced plasticity effect, which leads to a high tensile strength of ~1.3 gigapascals with a uniform elongation of ~9% and an excellent work-hardening capacity of >300 megapascals. This approach creates a pathway for concentration-modulated heterogeneous alloy design for structural and functional applications.