Selective Laser Melting of High Relative Density and High Strength Parts Made of Minor Surface Oxidation Treated Pure Copper Powder

Abstract

Pure Copper (Cu) is very difficult to prepare using selective laser melting (SLM) technology. This work successfully prepared the pure Cu with high relative density and high strength by the SLM technology using a surface oxidation treatment. The gas-atomized pure Cu powder was used as the feedstock in this work. Before the SLM process, the pure Cu powder was initially handled using the surface oxidation treatment to coat the powder with an extremely thin layer of Cu2O. The SLMed highly dense specimens contain α-Cu and nano-Cu2O phases. A relationship between the processing parameters (laser power (LP), scanning speed (SS), and hatch space (HS)) and density of Cu alloy in SLM was also investigated. The microstructure of SLMed Cu consists of fine grains with grain sizes ranging from 0.5 to ~30 μm. Tensile testing and detailed microstructural characterization were performed on specimens in the as-SLMed and pure copper state specimens. The mechanical property experiments showed that the specimens prepared by SLM technology containing nano-oxide phases had higher yield strength and tensile strength than that of other SLM-built pure copper. However, the elongation was remarkably decreased compared to other SLM-built pure copper, due to the fine grains and the nano-oxides.

Keywords

• nanoparticles
• oxidation
• microstructure
• selective laser melting
• tensile properties