Influence of Fe content on the microstructure and mechanical properties of Al-7Si-0.7Mg-2.8Fe alloy processed by laser powder bed fusion

Iron contamination is a major concern in aluminum alloys recycling. It is considered the main deleterious contamination due to its low solubility in the aluminum matrix leading to the formation of Fe-rich intermetallic phases with platelet-like morphology, which act as stress risers deteriorating the mechanical properties. This paper investigates the effect of Fe contamination in the microstructure and mechanical properties of Al–7Si-0.7Mg-2.8Fe alloy processed by Laser Powder Bed Fusion (LPBF). Microstructure characterization was carried out by Optical Microscopy (OM), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Transmission Electron Microscope (TEM). The mechanical characterization was performed by Vickers microhardness and tensile tests. The LPBF sample was analyzed in two directions, vertical and horizontal. The results show that the LPBF process provided a microstructural refinement and reduction of the aspect ratio of α-AlFeSi phase and silicon particles, leading to a strong improvement in mechanical properties when compared to the Fe-contaminated as-cast Al–7Si-0.7Mg-2.8Fe alloy.