Mechanical and thermal performance of additively manufactured copper, silver, and copper-silver alloys

Abstract

On-demand additive manufacturing (3D printing) offers great potential for the development of functional materials for the next generation of energy-efficient devices. In particular, novel materials suitable for efficient dissipation of localised heat fluxes and non-uniform thermal loads with superior mechanical performance are critical for the accelerated development of future automotive, aerospace, and renewable energy technologies. In this regard this study reports the Laser Powder Bed Fusion (L-PBF) processing of high purity (>99%) copper (Cu), silver (Ag) and novel copper-silver (CuAg) alloys ready for on-demand additive manufacturing (AM). The processed materials were experimentally analysed for their relative density, mechanical and thermal performance using X-ray computed tomography (X-CT), destructive tensile testing and Laser Flash Apparatus (LFA) respectively. It was found that while Ag featured higher failure strains, Cu in comparison showed a 109%, 17% and 59% improvement in yield strength (𝜎𝑦), Youngs Modulus (E) and ultimate tensile strength (UTS) respectively. As such the 𝜎𝑦, E and UTS for L-PBF Cu is comparable to commercially available L-PBF Cu materials. CuAg alloys however significantly outperformed Ag, Cu, and all commercial Cu materials when it came to mechanical performance offering significantly superior performance. The 𝜎𝑦, E and UTS for the novel CuAg composition were 105%, 33% and 94% higher in comparison to Cu. Although slightly different, the trend continued with a 106% and 91% rise for 𝜎𝑦 and UTS respectively for CuAg in comparison to industry-standard Cu. Unfortunately, E values for industry-standard Cu alloys were not available. When it came to thermal performance, L-PBF Ag was found to offer a 70% higher thermal diffusivity in comparison to Cu despite the variation in density and porosity. CuAg alloys however only showed a 0.8% variation in thermal performance despite a 10% to 30% increase in Ag. Overall, the study presents a new understanding regarding the 3D printing and performance of Cu, Ag and CuAg alloys.