Fabrication of carbon nanotube reinforced aluminum matrix composite by spark plasma sintering and hot extrusion hybrid process

Carbon nanotubes (CNTs) with their outstanding properties are expected as reinforcement for conventional materials, though they are required to be uniformly dispersed with the host matrix. However, uniform dispersion of CNTs within metal and ceramic-based materials is highly challenging to achieve due to strong van der Waal's forces between the neighboring CNTs leading to strong CNT agglomeration. We fabricated fully dense, uniformly dispersed 1.0 and 5.0 vol% CNT-aluminum matrix composite by combination of hetero agglomeration method and spark plasma sintering (SPS) followed by hot extrusion process. Tensile response and microstructure of the composites were studied by the universal Instron tester and transmission electron microscope, respectively. We realized a considerable enhancement in tensile strength of the composites while reaching the same rapture elongation for the 1.0 vol% CNT composite as the cast pure aluminum, however, the rupture elongation for the 5.0 vol% CNT composite was reduced. Although the aluminum was infiltrated into the surface defects of CNTs after the SPS, however, no Al₄C₃ phase was observed at the CNT/aluminum interface.