A high-strength Al-Si-Mg alloy was prepared by adopting selective laser melting (SLM), and then compared to the as-cast Al-Si-Mg alloy in terms of phase composition, microstructure, element distribution, crystallographic characteristics, and mechanical properties. It is found that Al-Si-Mg alloy prepared by SLM consists of α-Al matrix and eutectic Si particles, and the diffraction peaks of α-Al solid solution shift to lower angles due to the solid solution strengthening effect of Fe and Mg elements. The Al-Si-Mg alloy prepared by SLM has grain size approaching 18.35 μm, the dislocation density of 1.91×10¹⁵/m², the surface hardness of (117.8±4.7) HV, the tensile strength of (436±13) MPa, and the elongation of (7.98±0.27)%, presenting superior performance than the as-cast Al-Si-Mg alloy. The alloy prepared by SLM technology is under the synergetic effect of fine grain strengthening, solid solution strengthening, dislocation strengthening and second phase strengthening, and the ductile fracture is its main failure mechanism.

selective laser melting (SLM)  /  3D printing  /  additive manufacturing  /  Al-Si-Mg alloy  /  hardness  /  tensile strength  /  strengthening mechanism  /  solid solution strengthening  /  fine grain strengthening  /  dislocation strengthening