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Selective laser melting (SLM) technology has received great attention in recent years for its application in the fabrication of Cu-Sn-based devices used in a wide range of industries, such as aerospace, ocean engineering, etc. However, the SLMed Cu-Sn alloys have different microstructure and properties, compared with the alloys made by traditional process, especially after heating treatments. In this paper, the effects of heat-treatment processing parameters on the microstructure and mechanical strength have been investigated for the SLMed Cu-10Sn alloy. A dense Cu-10Sn alloy bulk specimen was obtained by optimizing the SLM processing, and the relative density of the specimen reached above 99%. The grain morphology was mainly the columnar dendrite and inter-dendritic phases formed along the solidification direction. Tensile testing and detailed microstructural characterization were carried out on specimens in the as-SLMed and heat-treated conditions. The strength and plasticity of the SLMed specimen are much higher than that of the casted Cu-l0Sn alloy, mainly because of the grain refinement in the grain of the SLMed specimen. After the 800°C solution treatment, and the 400°C aging treatment, the microstructure of the specimen transformed from the columnar grain to equiaxed grain, the dislocations reduced, and a lot of twins generated obviously. Therefore, the yield strength (σ0.2) of the heat-treated specimen was decreased compared to the as-SLMed specimen. However, the UTS and the elongation were increased, due to the interaction between twins and equiaxed grain.
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