Effect of hot extrusion on the microstructure and mechanical properties of (SiCw-SiCp)/2024Al hybrid nanocomposites

In order to investigate the hot deformation behaviour of SiCw · SiCp/2024Al hybrid composites, 2024Al reinforced with both whiskers and nanoparticles of silicon carbide were fabricated by squeeze casting, and hot extrusion was conducted subsequently. The mechanical properties of the hybrid composites were measured before and after deformation. Microstructure of the composites was observed by SEM and TEM. Microstructure observation results show that the reinforcements distribute homogeneously in the matrix of the as-cast composites and they are bonded well. Hot extrusion leads to a directional distribution of the SiC whiskers and a more homogenous spatial distribution of the SiC nanoparticles in the composites. Tensile test indicates that the strength of the composites increase with increasing content of the nanoparticles and raise further after extrusion. Compared with the matrix, the ductility of hybrid composites decreases obviously and are improved after extrusion.