Microstructural and mechanical characterization of steel-copper composite structures fabricated by laser powder bed fusion and induction melting

Composite structures, coupling properties from different materials, are systematically evaluated, examined with different fabrication processes. In this work, a hybrid fabrication process is proposed for steel-Cu metal-metal composites: Laser Powder Bed Fusion is utilized for printing 316L stainless steel lattices, which are later infiltrated with CuCrZr alloy powder, melted through induction heating. Microstructure characterization is accompanied by neutron imaging analysis, providing insight into critical aspects of the structures regarding the texture and strain distribution after each fabrication step, and the austenite-to-ferrite transformation on the steel-Cu interface. Thermodynamic modeling of the induction melting process examines the elemental interdiffusion phenomena, showing the impact of inter-difussion in the formation of a ferritic band on the steel-Cu interface. The mechanical performance of the composites is characterized by nano hardness indentation and compression testing, revealing the impact of the 316L lattice in reinforcing the overall hardness and strength of the composites. The current work proposes an alternative fabrication route for crack free steel-Cu composites, where the AM structure and the induction heating condition can be used as a tool to control the microstructure and the mechanical performance of the composites.