Interfacial characterization of SLM parts in multi-material processing: Metallurgical diffusion between 316L stainless steel and C18400 copper alloy

• Multi-material processing was successfully implemented and demonstrated in SLM.
• Bi-metallic laminates of steel/Cu were successfully produced with the SLM process.
• A substantial amount of Fe and Cu diffusion was observed at the bond interface.
• Good metallurgical bonding was obtained at the interface of the steel/Cu laminates.
• Highly refined microstructure was obtained due to rapid solidification in SLM.

Multi-material processing in selective laser melting using a novel approach, by the separation of two different materials within a single dispensing coating system was investigated. 316L stainless steel and UNS C18400 Cu alloy multi-material samples were produced using selective laser melting and their interfacial characteristics were analyzed using focused ion beam, scanning electron microscopy, energy dispersive spectroscopy and electron back scattered diffraction techniques. A substantial amount of Fe and Cu element diffusion was observed at the bond interface suggesting good metallurgical bonding. Quantitative evidence of good bonding at the interface was also obtained from the tensile tests where the fracture was initiated at the copper region. Nevertheless, the tensile strength of steel/Cu SLM parts was evaluated to be 310 ± 18 MPa and the variation in microhardness values was found to be gradual along the bonding interface from the steel region (256 ± 7 HV0.1) to the copper region (72 ± 3 HV0.1).