Experimental investigation on the electrical, thermal, and mechanical properties of laser powder bed fused copper alloys

Abstract

This paper presents a thorough investigation of the material characteristics of laser powder bed fused copper alloys. Three different copper alloys, i.e., pure copper, with phosphorus and zinc acting as the main alloying elements, were investigated. The research started by characterizing the starting copper powders and then identified the best process windows for laser powder bed processing to obtain samples with the highest density. Based on the results of process optimization, the electrical, thermal and mechanical properties, i.e., tensile strength, resistance to indentation, and roughness, were characterized. The experimental data showed a maximum relative density of approximately 91% for both alloyed powders, while that of the pure powder was limited to 84.6%. The presence of pores is considered the main limiting factor that inhibits the electrical conductivity, which is up to 68.4 IACS% for the Zn-added powder, and the resistance to indentation, in which the resistance to indentation of pure copper is half that of the zinc-alloyed powder. The tensile properties experience anisotropy caused by the manufacturing process itself, as highlighted by the X-ray diffraction analysis carried out after the samples were fabricated. The zinc-added powder shows the best tensile properties, reaching a tensile strength of 400 MPa, which is almost twice that of traditional annealed bulk copper (i.e., 210 MPa). Finally, the roughness is still far from that achievable with classical subtractive techniques, with values of approximately 7 μm for the best pure copper specimens.