The enhancement of laser absorptivity and properties in laser powder bed fusion manufactured Cu-Cr-Zr alloy by employing Y2O3 coated powder as precursor

It is always a great challenge to laser additive manufacture high-performance metal parts with high laser reflectivity, such as Cu based alloys, Al-Si based alloys and so on. In this work, the uniform thin Y2O3 coating was successfully introduced on the surface of the Cu-Cr-Zr powders by an in-situ chemical method. This Y2O3 coating can reduce the laser reflectivity of Cu-Cr-Zr powders without destroying their sphericity. The effect mechanism of Y2O3 on the microstructure, mechanical properties and electrical conductivity of CuCr-Zr specimens was further clarified. The grain size of the LPBF manufactured specimens is much smaller in case of Y2O3 doped Cu-Cr-Zr powder than that of the Cu-Cr-Zr powder. The Cu2CrZr(Y, O) nanoparticles with the size of similar to 50 nm form in the Cu matrix of Y2O3 doped Cu-Cr-Zr specimens, in addition to the Cr and Cu2CrZr precipitated particles. These Cu2CrZr and Cu2CrZr(Y, O) precipitated particles both exhibit a coherent interface with Cu matrix. Due to the refined grains and coherent second phase nanoparticles within grains mentioned above, the yield strength and ductility of Y2O3 doped Cu-Cr-Zr specimens are both improved significantly compared with the yield strength and ductility of undoped Cu-Cr-Zr specimens. Furthermore, the correlation between microstructure and properties of the Y2O3 doped Cu-Cr-Zr alloys manufactured by LPBF was also clarified. Our work provides a new strategy and in-depth view for the laser additive manufacturing of high-performance copper alloys and other alloys with high laser reflectivity. (c) 2022 Elsevier B.V. All rights reserved.