Influences of Different Additives on Laser-Based Additive Manufacturing of Pure Aluminum

Al powders with low laser absorptivity are essentially incompatible with laser powder bed fusion, as the retention of a large number of unmelted particles leads to inferior mechanical properties in Al builds. In this study, the influences of different additives on laser-based additive manufacturing of pure Al were studied. Nano-CuO or GO sheets were coated onto the pure Al powders without apparent agglomeration via electrostatic attraction during the hetero-agglomeration process. Apart from retaining a similar shape and particle size to the initial pure Al powders, the decorated powders exhibited improved laser absorptivity and flowability, contributing to satisfactory fusion under laser irradiation. Moreover, the mechanical performance of the Al build was enhanced by the addition of these additives, which is mainly caused by the lower porosity, solid-solution strengthening introduced by Cu, O, or C atoms, and the precipitation-dispersion strengthening. This study will benefit the effective selection of reinforcing materials for Al alloy L-PBF builds.