Material extrusion additive manufacturing of bi- metal structures: A numerical and experimental study of interfacial microstructure

Bi-metal structures attract significant attention in research and industry due to their great performance and superior functionality. However, the formation of interface has not been comprehensively investigated due to the lack of methodologies to unveil the bonding mechanism between dissimilar materials. In this study, we developed a discrete element-based modeling and simulation to predict and understand the micro-scale bonding of stainless steel and nickel superalloys built by a printing, debinding, and sintering process. Two governing diffusion mechanisms were implemented to reveal the microstructural evolution from loose particles to a dense bi-metal component. The densification and grain growth of the interface were simulated and validated by experimental observations through scanning electron microscopy and electron backscatter diffraction analysis. Our simulation can accurately predict the interfacial microstructure, demonstrating a successful adoption of the modeling and simulation methodology to understand the interfacial formation of dissimilar materials shaped by AM and bonded by solid-state sintering.