Heat Treatment Effects on Laser Powder Bed Fused CuNi2.5SiCr Alloy: Microstructure, Hardness, Electrical, and Thermal Conductivity

Additive manufacturing of copper alloys remains challenging due to their high reflectivity and thermal conductivity, which limit laser energy absorption and increase energy consumption. In this study, the laser powder bed fusion of a copper-based CuNi2.5SiCr alloy is demonstrated using low laser powers (67.2-100.8 W). Samples fabricated at 67.2 W achieved a relative density of 96.8%, with no significant improvement observed at higher laser powers. The post-process heat treatments were conducted at 750 °C, 850 °C, and 950 °C to investigate their influence on microstructure, hardness, electrical and thermal conductivity. Heat treatment at 850 °C resulted in the highest hardness, improved microstructural uniformity and 20 W/mK thermal conductivity, while the as-fabricated samples exhibited the highest electrical conductivity (1.07 × 10⁶ S/m).