Multi-material laser powder bed fusion: effects of build orientation on defects, material structure and mechanical properties

Multi-Material Laser Powder Bed Fusion (MM-LPBF) offers a novel approach for fabricating high-resolution components with both spatially tailored material properties and design by leveraging selective powder deposition (SPD) in conventional LPBF processing. This study analyzes the effect of build orientation as a contributing factor to material compatibility, process-induced defects, and interfacial formation mechanisms to elucidate the process-structure-property framework for MM-LPBF. New MM-LPBF capabilities are demonstrated through a complex gyroid structure (904L stainless steel and bronze) for unique MM-LPBF signatures (e.g., melt pool characteristics, grain morphology, defects, and mechanical properties). Fracture mechanisms in MM-LPBF are investigated through multi-scale domain techniques, including flexural testing supported by digital image correlation (DIC), finite element analysis (FEA), and intermittent micro-CT. Findings from this study demonstrate the current technological opportunities and challenges in the adoption of MM-LPBF for a wide range of applications such as thermo-fluidic surfaces, solid-state energy storage, and biodegradable implants.