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Laser processing of pure Cu is often challenging because of Cu's very low absorptivity to most laser beams, and this difficulty is applicable to the recently developed laser powder bed fusion (LPBF) additive manufacturing (AM). How to realize high-quality LPBF forming is urgently pursued to maximize its advanced manufacturing potential in directly making various Cu parts. Herein, two approaches have been applied, individually or simultaneously, to address the poor printability problem of the pure Cu: one is to conduct intentional oxidation treatment to the pure Cu powder to vary its surface structure and then enhance its laser absorptivity; and the other is to adopt laser remelting to counter its high thermal conductivity and provide extra liquid phase for better densification. Various research means were used to investigate mechanical performances, microstructural details, and electrical performance of the as-printed Cu. Results show that a maximum relative density of ≈99.0% can be realized by using the two approaches simultaneously, while oxidation temperature and remelting times are the two important factors to be considered. The methodology developed in this study is expected to be applicable to other highly reflective materials as well.

Selective laser melting is an additive manufacturing technique that can be used to achieve excellent forming of Cu alloys. Specifically, high-Sn–Cu alloys (e.g., Cu–10Sn) offer good wear and corrosion resistance, and are extensively used in industrial applications. Although P is considered a beneficial element in Cu–Sn alloys, particularly with respect to ductility, P-doped Cu–10Sn alloy (Cu–10Sn–0.4P) has not yet been investigated in detail. Thus, herein, it provides valuable insights regarding the printability, residual stress level, heat treatment conditions, mechanical properties, and microstructural features of selective laser melted Cu–10Sn–0.4P. The alloy is successfully printed using a relatively wide range of processing parameters. The high levels of residual stress after printing were relieved using heat treatment under appropriate conditions. Consequently, a good combination of strength, ductility, and hardness was achieved. The addition of P led to an improved oxygen scavenging capability, thus Cu–10Sn–0.4P alloy exhibited a better ductility than P-free Cu–Sn alloy. The excellent printability of Cu–10Sn–0.4P is demonstrated by printing a variety of objects, including flanges, sheathings, and jewelry rings. © 2021 Wiley-VCH GmbH

Laser processing of pure Cu is often challenging because of Cu's very low absorptivity to most laser beams, and this difficulty is applicable to the recently developed laser powder bed fusion (LPBF) additive manufacturing (AM). How to realize high-quality LPBF forming is urgently pursued to maximize its advanced manufacturing potential in directly making various Cu parts. Herein, two approaches have been applied, individually or simultaneously, to address the poor printability problem of the pure Cu: one is to conduct intentional oxidation treatment to the pure Cu powder to vary its surface structure and then enhance its laser absorptivity; and the other is to adopt laser remelting to counter its high thermal conductivity and provide extra liquid phase for better densification. Various research means were used to investigate mechanical performances, microstructural details, and electrical performance of the as-printed Cu. Results show that a maximum relative density of ≈99.0% can be realized by using the two approaches simultaneously, while oxidation temperature and remelting times are the two important factors to be considered. The methodology developed in this study is expected to be applicable to other highly reflective materials as well.