Study of Printability, Microstructure, and Hardness of Al-4Mn-1.3Mg-0.3Zr Alloy Produced by Powder Bed Fusion–Laser Beam

In this study, the microstructure and defects of an Al-Mn-Mg-Zr alloy produced by the Powder Bed Fusion–Laser Beam (PBF-LB) technology are investigated. The influence of the process parameters on the microstructure and defects is demonstrated. Aluminum alloys are usually prone to cracking during solidification. However, finding the optimal parameters of the PBF-LB process yielded three-dimensional specimens of Al-Mn-Mg-Zr alloy with densities reaching 99.6% of the theoretical value, free from cracks. It is shown that manganese not only precipitates as a brittle Al₆Mn intermetallic compound after solidification but also forms a supersaturated solid solution of manganese in aluminum. The influence of the process parameters on the surface roughness of the manufactured samples and their microhardness was evaluated. It is also shown that the cooling rate of the melt pool has an effect on the microstructure of the samples obtained at the optimal process parameters.