Microstructural evolution of hybrid aluminum matrix composites reinforced with SiC nanoparticles and graphene/graphite prepared by powder metallurgy

The dispersion of ceramic nanoparticles is of significance to the microstructure and properties of particulate reinforced metal matrix composites. In this study, two hybrid enhancers, SiC-graphite and SiC-graphene nanosheets (GNSs), were incorporated into aluminum matrix composites using powder metallurgy. The dispersion of the reinforcements and microstructural evolution of the composites were characterized by using Scanning Electron Microscopy, X-Ray Diffraction, Transmission Electron Microscopy, and Raman spectroscopy. The results show that thin GNSs accelerated the deformation of the aluminum particles, and defects were introduced into the carbonaceous phases during the ball milling process. Al4C3 needles generated during hot pressing, and were observed to bridge the aluminum grains. Compared with graphite, GNSs were more uniformly dispersed throughout the composite, which in turn restrained grain growth. As a result, a nanostructured composite (57.7 nm) was successfully produced upon the addition of SiC-GNSs.