Additive manufacturing of fine-structured copper alloy by selective laser melting of pre-alloyed Cu-15Ni-8Sn powder

In this work, Cu-15Ni-8Sn components were manufactured by selective laser melting (SLM) with a near full density of about 99.4%. The microstructures and phase precipitation of the as-fabricated Cu-15Ni-8Sn alloy were characterized by X-ray diffraction (XRD), electron probe microanalyzer (EPMA), electron back-scattered diffraction (EBSD), and transmission electron microscope (TEM). It was demonstrated that the as-fabricated Cu-15Ni-8Sn alloy shows α-phase with γ-precipitates by XRD and TEM. The size of the grains of α-phase is in the range of 5~20 μm with random orientation distribution. The γ-precipitate is a Sn- and Ni-rich phase distributed dispersedly in matrix and accumulatively in grain boundary. The as-fabricated Cu-15Ni-8Sn alloy exhibited yield strength of 522 MPa, ultimate tensile strength of 653 MPa, and elongation of 17%. The excellent mechanical performance of the as-fabricated Cu-15Ni-8Sn alloy is caused by the local laser melting mode including rapid cooling rate and reduplicative fusing from the subsequent layer melting, which leads to refined grains and limited Sn segregation in micron-size within the matrix.