Effect of Cu, Ni addition on the CNTs dispersion, wear and thermal expansion behavior of Al-CNT composites by molecular mixing and mechanical alloying

Carbon Nanotubes (CNTs) are used as ideal reinforcement due to their high strength, high elastic modulus and high aspect ratio in fabrication of metal matrix composites. But the uniform distribution of the nano reinforcements (CNTs) in the matrix is very difficult to achieve due to their high aspect ratio and Van der Waals force among them. Due to this effect the expected properties may not be achieved in the resulting composites. To overcome this issue and improve the distribution of CNTs in the matrix the Molecular Level Mixing (MLM) of CNTs with Cu/Ni followed by Mechanical Alloying (MA) can be used effectively with functionalized CNTs. Micron sized Cu-CNTs and Ni-CNTs composite powders were prepared by MLM. Then the composite powder was mixed with Al matrix powder by MA. The composite powder obtained after MA were consolidated using spark plasma sintering (SPS). The Microstructure of the sintered Al/Cu-CNT and Al/Ni-CNT composites was characterized by Optical microscope, Scanning Electron Microscope (SEM). Also hardness, wear and thermal expansion were measured. The results show that mechanical properties of the Cu and Ni coated CNTs reinforced composites are enhanced when compared with Al/CNT composite and pure Al sample. This is due to uniform distribution of CNTs in the Al matrix and strong interfacial bonding. [Display omitted] •Molecular mixing provides uniform dispersion of CNTs and enhances the properties of Cu and Ni coated CNT composites.•The presence of Al4C3 phase at the Al-CNT interface aids better load transfer between matrix and reinforcement.•Cu and Ni coated CNT composites possess better mechanical properties than Al-CNT composites.•CoF curves of composites resembles rolling friction pattern which is due to self lubricating action of CNTs.