Influence of characteristic parameters of SiC reinforcements on mechanical properties of AlSi10Mg matrix composites by powder metallurgy

The bottleneck problems of SiC particles reinforced AlSi10Mg composites (SiC/AlSi10Mg) prepared by traditional casting method, such as composition segregation, interface reaction and coarse microstructure, can be effectively improved by powder metallurgy with lower processing temperature. In this study, the influence of SiC particle size and content on the properties of SiC/AlSi10Mg was systematically analyzed. SiC/AlSi10Mg composites were prepared by planetary ball milling, spark plasma sintering (SPS) and hot extrusion composite preparation process. The obtained composites presents dense microstructure without the formation of interfacial reaction phase. The distribution of micron SiC particles (μm-SiC) in the matrix is relatively uniform, and nano SiC particles (nm-SiC) slightly agglomerates with the increase of the content. The strength of SiC/AlSi10Mg increases with the increase of nm-SiC content, which is mainly attributed to dispersion strengthening, dislocation strengthening and grain refinement strengthening. The strength of SiC/AlSi10Mg hardly changes with the increase of μm-SiC content, but the elongation decreases gradually. The deformation between μm-SiC and AlSi10Mg matrix is not coordinated and μm-SiC cleave the AlSi10Mg matrix. The irregular boundaries of μm-SiC are easy to produce stress concentration during loading, leading to interface cracking or μm-SiC fracture. Therefore, μm-SiC are difficult to play a significant strengthening effect to composites. With the increase of SiC content, the fracture mechanism of composites gradually changes from ductile fracture to brittle fracture in SiC agglomeration region. This study lays a theoretical and experimental foundation for the controllable preparation and performance optimization of high strength and toughness AMCs reinforced by SiC particles.