Re-Imagining Additive Manufacturing through Multi-Material Laser Powder Bed Fusion

Abstract

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 capitalizing on selective powder deposition (SPD) in conventional laser powder bed fusion (LPBF) processing. Advancements in multi-material additive manufacturing (AM), specifically MM-LPBF is now presenting a unique opportunity to reimagine additive manufacturing as we know today in terms of the local material assignment, AM-processing induced properties and design complexity which can help achieve functional requirements across multiple length scales. In this study, new MM-LPBF capability to manufacture a sheet-based gyroid structure composed of 904L stainless steel and bronze (CuSn10) is studied for unique MM-LPBF signatures (e.g., melt pool characteristics, grain morphology and mechanical properties via intermittent micro-CT during flexural testing). The fracture mechanics of complex multi-material structures is investigated through multi-scale domain techniques, including mechanical testing (supported by digital image correlation (DIC), finite element analysis (FEA), and intermittent micro-CT), microstructural and morphological characterization of the bimaterial interface. This study analyzes the contribution of factors such as thermomechanical material compatibility, process-induced defects, cracking, porosity, and microstructure to determine the ultimate origin of failure and propagation patterns. Interface formation mechanisms are explored to elucidate process-structure-property framework for MM-LPBF. Findings from this study clearly demonstrate both the opportunity of MM-LPBF and current technological challenges to further advance the adoption of MM-LPF for a wide range of applications such as thermo-fluidic surfaces, solid-state energy storage, and biodegradable implants, among others.