Laser Powder Bed Fusion of Microscale-Sic-Particle-Reinforced Alsi10mg Matrix Composites: Microstructure, Porosity, and Mechanical Properties

Adding SiC particle (SiCp) to Al alloys to form Al/SiCp composite can increase the elastic modulus and reduce the thermal expansion coefficient of the material. Therefore, in this study, the microstructure, porosity and thermal expansion coefficient, and mechanical properties of AlSi10Mg-10 vol.% SiCp composite fabricated by laser powder bed fusion (LPBF) were investigated. The ultimate tensile strength, compressive strength, compressive modulus, and the thermal expansion coefficient of LPBF-formed AlSi10Mg/SiCp composite are 351 MPa, 861.9 MPa, 181.9 GPa and 18.23 × 10−6 m·°C−1, respectively. The results show that the character of the formed Al4SiC4 phase plays a decisive role in the mechanical properties of the LPBF-formed AlSi10Mg/SiCp composite that decrease with increasing the laser power and the decreasing laser scanning speed when the laser power is higher than 320 W and the laser scanning speed is lower than 1100 mm/s. While the thickness of long-stripe Al4SiC4 and the length of the needle-like Al4SiC4 increase the increasing laser power and the decreasing laser scanning speed. Moreover, the use of the Ev equation to evaluate the effect of LPBF parameters on mechanical properties and relative density of the composites is accurate when only one parameter changes in the Ev equation. These results provide guidance for endowing the SLM-deposited AlSi10Mg/SiCp composite with a combination of high strength, hardness, and relative density.