Influence of the Low-Melting Additive Type on the Structure and Mechanical Properties of an Aluminum Composite Produced by LPBF

The paper investigates the structural formation features and their effect on the mechanical properties of Al-20Sn and Al-20Pb (vol.%) alloys produced by laser powder bed fusion (LPBF) from a mixture of commercial elemental powders. The mixture of Al and Pb or Al and Sn powders was spread with a doctor blade onto a heated substrate and laser-irradiated to produce compact samples via LPBF. Synthesis was carried out at a constant laser scanning speed of v = 1.2 m/s and power levels ranging from 70 to 130 W. The results confirmed that the structure of the resulting aluminum composites strongly depends on the physical and thermodynamic properties of the soft alloying additive and differs significantly at equal volume concentrations. In the case of the Al-20Sn composite, it exhibits a dendritic morphology, whereas for Al-20Pb, it shows a cellular structure. Compression tests demonstrated that increasing the laser power up to 130 W enhances the plasticity of the LPBF-processed Al-20Pb composite, reaching 25%, which is substantially higher than that of the Al-20Sn alloy. Meanwhile, the ultimate compressive strength σU of both alloys was approximately equal, standing at about 100 MPa. The main failure mechanisms of the studied alloys are discussed.