Microstructure evolution and mechanical properties of TiB/Ti6Al4V gradient-material lattice structure fabricated by laser powder bed fusion

Abstract

The lattice structure with graded composition and microstructure in function of position, allowing for smooth transition and combination of multiple desirable features, has great prospects in various applications. Laser powder bed fusion (LPBF) is an effective approach to preparing the gradient-material lattice structure by altering the proportion of raw powder materials. In this study, in-situ TiB/Ti6Al4V gradient-material bulk samples and Schoen Gyroid scaffolds with various relative densities were manufactured by LPBF for the first time. Microstructure evolution, manufacturing quality, and mechanical responses were analyzed in detail. The results show that the graded layers exhibit good metallurgical bonding with irregular band-shaped transition zones at the interface. The in-situ synthesized TiB phase particles improve the strength and grain refinement, but decrease the dimensional accuracy and induce more defects. The elastic modulus and compressive yield strength of gradient-material lattice structures increase with the rise of the relative density. The TiB/Ti6Al4V gradient-material lattice structures have higher stiffness and strength compared with homogeneous Ti6Al4V counterparts. A combined model for predicting and designing the mechanical properties of lattice structures with graded layers is used to offer a new methodology to design complex components with multiple materials combined with superior performances.