High-strength and high-conductivity additively manufactured Cu-O alloy enabled by cellular microstructure

Printing Cu alloys with simultaneously high strength and high electrical conductivity by laser powder bed fusion remains a challenge. In conventionally manufactured Cu alloys, nanoprecipitates form through alloying elements to impart significant strengthening effects while having a lesser impact on electrical conductivity. However, the ultrahigh cooling rate of laser powder bed fusion promotes the supersaturated solid solution of alloying elements, resulting in severe lattice distortion in the Cu matrix and a significant compromise in electrical conductivity. Therefore, it is vital to select Cu alloying elements that substantially prevent the formation of a supersaturated solid solution in laser powder bed fusion to achieve outstanding strength while maintaining sufficient electrical conductivity. In this study, we fabricated a Cu-O alloy with high strength (491.6 MPa) and high electrical conductivity (68.0 % IACS) using laser powder bed fusion. The alloy features a cellular microstructure in which Cu2O nanoprecipitates are configured orderly as the cellular boundary. This cellular microstructure can promote strength by impeding dislocation motion and maintain a high electrical conductivity by preserving a longer free path for conductive electrons. This study explores the potential of combining the alloy composition and extreme process conditions of laser powder bed fusion to provoke unique microstructures and overcome the dilemma between strength and electrical conductivity in Cu alloys.