Enhanced mechanical behavior and fabrication of silicon carbide particles covered by in-situ carbon nanotube reinforced 6061 aluminum matrix composites

•A novel nano/micro-sized SiCp(CNT) hybrid reinforcement was synthesized by in-situ growth of CNT on the surface of SiCp.•The morphology of SiCp(CNT) was greatly affected by the size of SiCp.•SiCp(CNT)/6061Al hybrid composite with CNT well-dispersed was fabricated by a conventional powder metallurgy process.•The strength and ductility of hybrid composites were simultaneously enhanced by the addition of SiCp(CNT).

Due to its outstanding performance, carbon nanotube (CNT) has shown great potentials as an enhancement material for composites. However, CNT tends to cluster together or form aggregates during fabrication process, it is a challenging task to effectively mix CNT into a metal matrix. In this study, a novel approach is proposed to disperse CNT into aluminum matrix by using silicon carbide particles (SiCp) as a “carrier”. Through chemical vapor deposition, CNT is grown on the surface of micro-sized SiCp forming a nano/micro-sized hybrid reinforcement, which is named as SiCp(CNT), and then they will be homogeneously distributed in the 6061Al matrix by conventional powder metallurgy process. Three types of SiCp(CNT), with SiCp sizes being 13 μm, 7 μm, 2.5 μm, were used for finding out the effect of SiCp size on the morphology of SiCp(CNT), the microstructure and mechanical properties of the obtained composite. The most significant improvement in tensile properties can be found for the case with the SiCp size to be 7 μm, which has ductility of 8.5%, Young's modulus of 98 GPa, and tensile strength of 428 MPa. This remarkable strengthening effect is attributed to the increase of the “punched zone” size with the presence of CNT on the SiCp surface.

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