Microstructure Evolution, Property Analysis, and Interface Study of 3%CF-3%SiC-10%SiC Functional Gradient Aluminum Matrix Composites

To overcome the limitations of the low strength and plasticity in the application of aluminum (Al)-based composites, a functional gradient Al matrix composites of 3 vol% carbon fiber (CF)-3 vol% SiC-10 vol% SiC, with excellent comprehensive performance, was prepared by spark plasma sintering (SPS) technology. The microstructure of the layers and interlayer interfaces of the functional gradient composites (FGC) was analyzed in depth, and the mechanical properties and thermal conductivity were investigated. The results show that the differences in size and content between the CF and the SiC give different microstructural characteristics to the FGC’s various layers. The 3% and 10% SiC layers have a faster dynamic recrystallization process for the same deformation. The FGC has excellent mechanical properties, with a yield strength 167.12% higher than that of pure Al and plasticity close to that of pure Al. Before and after the hot rolling, the yield strength of the FGC is 149.65% and 62.46% higher than that of the single CF reinforced Al matrix composites, respectively. The interlaminar stresses generated by the changes in grain size and grain orientation are responsible for the interface failure. The texture evolution reveals two different recrystallization mechanisms in the CF and SiC layers. The difference in morphology and size of recrystallization grains under the two mechanisms leads to different mechanical properties of each layer.