AddFAST: A hybrid technique for tailoring microstructures in titanium-titanium composites

The advantages of FAST sintering have prompted much process research and application. From this came opportunities to investigate the potential for designing complex interpenetrating microstructures by combining the powder bed with a pre-built solid lattice structure, which bonds with the powder to become one. Producing the lattice structure through Additive Manufacturing yields a columnar grain morphology and texture, contrasting to the powder grains when bonded and creating a controllable composite microstructure of interpenetrating grain types. Here, we demonstrate with Ti-6Al-4V that this AddFAST technique successfully creates parts with this complex microstructure. The samples show a precise arrangement of grain sizes and texture with high densification and bonding. This demonstrates the technique's viability and the process parameter values that control the final microstructure, while showing the ability to combine different alloys within the part and to retain microstructural quality in deformation. Verifying this AddFAST process creates opportunities to design controlled, complex microstructures in small parts.