Influence of aluminum addition on the laser powder bed fusion of copper-aluminum mixtures

Abstract

• Created a system in which the liquid phase sintering process is established. • Aluminum was added to pure Cu to form Cu-rich mixtures with different Al contents. • The in-situ alloying of Cu-Al was achieved with an energy density (ED) two times lower than the ED used with pure Cu, leading to smoother and denser parts. • Achieved simultaneous joining and 3D printing mixtures of highly reflective metals. The high optical reflectivity of copper (Cu) in the near infrared (NIR) domain and its elevated heat dissipation make Cu a challenging metal for laser powder bed fusion (LPBF), even with high energy densities (EDs). In this study, we demonstrated that adding aluminum (Al) powder by as little as 0.75, 1.5, and 3 wt.% substantially enhances Cu processability, leading to denser (up to 98 %) and smoother (Ra = 3.3 μm) Cu-Al parts as compared to 95% and 18 μm, respectively, for the parts printed using pure Cu. In addition, this method reduces the ED required by a factor of two for the additive manufacturing of the Cu-based parts while maintaining a significant heat dissipation. These improvements are achieved due to the coexistence of solid Cu particles with liquid Al at the vicinity of the molten pool, accomodating the predensification of the powder mixture. The development of the semi-liquid 3D printing approach opens up a new path to easily print materials difficult to be printed for broadening their applications.