Influence of processing parameters on selective laser melted SiCp/AlSi10Mg composites: Densification, microstructure and mechanical properties

SiC particle reinforced Al matrix composites are increasingly applied in the automotive, military, aerospace and electronic encapsulation fields. In this work, SiC particle reinforced AlSi10Mg composites were fabricated by selective laser melting (SLM). The influences of processing parameters, such as laser power, hatching space and scanning speed, on density, microstructure and mechanical properties of the SLMed SiCp/AlSi10Mg composites were investigated systematically. Under the optimal processing parameters, 97.7% relative density of the SLMed composites was achieved. The SiC particles were distributed uniformly in AlSi10Mg matrix. The decomposition of SiC particles occurred during the SLM processing, and there was a reduction tendency of the SiC particle as the laser energy input increased. The microstructure was characterized by optical microscope, scanning electron microscope and X-ray diffraction. Due to the interfacial chemical reaction between SiC and the aluminum matrix, several the reaction products of the needle-shaped phases Al4SiC4 and faceted particles Si were formed, which dispersed in the primary alpha-Al dendrites and alpha-Al + Si eutectic matrix. The continuous and compatible chemical interface between the SiC particles and the matrix were found with no micro-pores or micro-cracks. Compared with the SLMed AlSi10Mg, the microhardness of the SLMed SiCp/AlSi10Mg composites (217.4HV(0.2)) increased, but the tensile strength (341.9 MPa) decreased obviously. The fracture mode of the SLMed composites was mainly brittle fracture. The main reasons for the early failure of the SLMed SiCp/AlSi10Mg composites were the existence of the pores in the aluminum matrix and the SiC particle cracking. At last, a thin-wall part with complicated structure made of 15 wt% SiCp/AlSi10Mg was fabricated successfully.