Enabling robust and energy-efficient laser powder bed fusion of Cu alloys via Mo nanoparticle decoration

Abstract

Laser Powder Bed Fusion (PBF-LB) of copper and low-alloyed copper alloys remains challenging due to their low infrared absorptivity and high thermal conductivity. This study introduces a multi-faceted strategy integrating computational thermodynamics-guided alloy design, Mo nanoparticle surface decoration, and thermal process optimization to enable robust and energy-efficient PBF-LB processing of reflective Cu-based alloys. Surface decoration with 0.44 wt% Mo nanoparticles enhances laser energy absorption, enabling a 40–45 % reduction in the required laser volumetric energy density from 167 to 188–100–118 J/mm³ to achieve > 99.1 % part density. Additionally, Mo addition improves the alloy’s resistance to precipitate coarsening while maintaining low solid solubility in Cu, thereby preserving electrical conductivity. In CuCrZr alloys, baseplate preheating to 300 °C promotes densification and in-situ precipitation of Cr and Cu_xZr_y phases during PBF-LB, enhancing both strength and conductivity. In contrast, Mo addition suppresses in-situ precipitation due to its sluggish diffusion in Cu and preferential partitioning into Cr and Cu_xZr_y phases. After direct age-hardening (450 °C, 9 h), the CuCrZrMo alloy exhibits a fine dispersion of Mo-doped nanoprecipitates, achieving a yield strength of 598 ± 7 MPa (vs. 576 ± 7 MPa for CuCrZr) while retaining high electrical conductivity (67–68 % IACS). This work highlights a synergistic alloy and process design strategy to address key PBF-LB challenges in Cu alloys, enabling their application in high-performance components requiring combined high mechanical strength and electrical conductivity.