Fatigue performance and material characteristics of SiC/AlSi10Mg composites by selective laser melting

By using selective laser melting, the SiC/AlSi10Mg composites were created. Under various process parameters, the impacts of SLM producing SiC/AlSi10Mg composites on density, microstructure, tensile characteristics, and fatigue properties were investigated. The results demonstrated that the density of the SiC/AlSi10Mg composites was closely related to the laser energy density. The density of SiC/AlSi10Mg composites might reach 99.7% under the ideal conditions. The Al4SiC4 phase grew with the rise in laser energy density as the aluminum matrix and SiC reacted in situ to generate a new strengthening phase Al4SiC4, which was dispersed on the matrix in a granular way. Therefore, the composite's tensile strength and microhardness reached their maximum values at 190.17HV and 435 MPa, respectively, when the energy density was 151.79J/mm3. This was due to the mixed strengthening mechanism caused by the SiC and Al4SiC4 reinforcing phase Compared with AlSi10Mg alloy, the addition of reinforcing phase SiC could significantly improve the fatigue resistance of composite materials. The fatigue fracture mode was brittle fractures, and the source of the crack was mainly from the surface pore defects. The size of the fatigue source defect size was related to the fatigue performance. The smaller the size of the defect, the more beneficial the fatigue resistance of the composite material.