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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. [ABSTRACT FROM AUTHOR]

The additive manufactured (AM) parts of aluminum alloys have been widely used in defense, aerospace, automotive and other industries. There is a growing demand for joining or repairing of the AM parts of aluminum alloys using welding technology. However, the problems of high porosity and joint softening are occurred when welding of aluminum alloy AM parts, which have become technical bottlenecks that need to be solved urgently. Laser welding of AlSi10Mg alloys fabricated by selective laser melting (SLM) with an addition of Er and Zr in the filler metal was carried out. The effect of Er and Zr addition on the porosity, microstructures and mechanical properties of the welded joints was investigated, and the contribute of Er and Zr addition to the yield strength (YS) of the welded joints was calculated. Compared that joints without Er and Zr addition, the average ultimate tensile strength (UTS) and YS of the welded joints with Er and Zr addition have been increased by 10.5% and 23.5%, respectively. The improved mechanical poverty of the welded joints is due to the refined α-Al grains and Si-rich cellular networks, and the reduced hydrogen pores occurred in the weld metal (WM) with the addition of Er and Zr. The YS calculation of the weld joints indicates the most important contribution to the YS is the enhancement effect of the Si-rich networks with Er and Zr. [Display omitted] • Filler metal with Er and Zr addition was introduced in laser welding of SLM AlSi10Mg alloys. • Er and Zr addition in Filler metal effectively reduces hydrogen pores generated in the WM. • Er and Zr addition in Filler metal greatly increases the UTS and YS of the welded joints. • Enhancing Si-rich network effect with Er and Zr addition is the most important contribution to the enhancement of YS. [ABSTRACT FROM AUTHOR]

• W-Cu10Sn composite with relative density of 99.36% was fabricated through SLM. • Completely melting W during SLM formed three dimensional connected structure. • Cracks within W were significantly restrained due to the evaporation and melting of Cu10Sn. Three-dimensional connected W-Cu10Sn composites materials with high relative density (99.36%) were fabricated through selective laser melting (SLM). The densification process of the composite balanced the melting of W, evaporation of Cu/Sn and the spreading of melted α-Cu. Under the optimized SLM parameters, high laser power (LP) melted the most of W powder, the adjacent laser scanning track with small hatch space (HS) could fuse W phase together. With small HS and low scanning speed (SS), the spreading of melted α-Cu could fill up the pores caused by the evaporation of Cu/Sn. Finally, a three-dimensional connected structure is formed by W phase, and α-Cu phase occupied the gaps the gaps among W phase. [ABSTRACT FROM AUTHOR]

Abstract Cu-10Sn alloy with body-center-cubic (BCC) lattice structure was fabricated through selective laser melting (SLM). The geometry of SLMed BCC lattice Cu-10Sn alloy (rod diammeter ∼300 μm, length ∼700 μm) was in good agreement with the design model. Similar with the nearly full density Cu-10Sn alloy, columnar also constituted the majority parts of the lattice structure Cu-10Sn, but exhibited various morphologies due to the different grain growth orientation under thermal effect. The gowth orientation of columnar grain in the rods oriented to the as-fabricated layer due to the higher thermal conductivity of the as-fabricated layers. Graphical abstract Image 1 Highlights • Cu-10Sn alloy with BCC lattice structure was fabricated through SLM. • The geometry of BCC lattice Cu-10Sn alloy was in good agreement with the design model. • The BCC lattice Cu-10Sn exhibited various grain morphologies under thermal effect. • The gowth orientation of columnar grain in the rods oriented to the as-fabricated layer. [ABSTRACT FROM AUTHOR]