Aluminum (Al)-based metal matrix composites reinforced with multiwalled carbon nanotubes were developed by powder metallurgy route. The Al and multiwalled carbon nanotubes powder mixtures were consolidated under a load of 565 MPa followed by sintering at 550℃ for 2 h in inert atmosphere. Al–1, 2, and 3 wt.% multiwalled carbon nanotube composites were developed. In the present study, the microstructure, mechanical properties, sliding wear behavior, and crystallographic texture of various Al–multiwalled carbon nanotube composites were investigated. The multiwalled carbon nanotubes produced by low-pressure chemical vapor deposition technique and the various sintered composites were characterized using scanning electron microscope, high-resolution transmission electron microscope, X-ray diffraction, differential scanning calorimetry and thermogravimetric analysis, Raman spectroscopy, and Fourier transform infrared spectroscopy. A significant improvement in relative density, Vickers microhardness, and wear resistance of the composites up to addition of 2 wt.% of multiwalled carbon nanotubes was observed. The deterioration in these properties beyond 2 wt.% of multiwalled carbon nanotubes was possibly due to the agglomeration of multiwalled carbon nanotubes in the Al matrix. The tensile strength of Al–multiwalled carbon nanotube composites continuously decreases with the addition of multiwalled carbon nanotubes. The decrease in tensile strength can be attributed to the detrimental effect of Al4C3 formed at the interface of the Al matrix and the multiwalled carbon nanotubes which will cause premature failure of the composite. The addition of multiwalled carbon nanotubes altered the crystallographic texture of the composites. The residual stresses in the various composites were found to be compressive in nature and also show improvement up to addition of 2 wt.% multiwalled carbon nanotubes in the Al matrix.
Ultrafine Grained Bulk Al Matrix Carbon Nanotube Composites Processed by High Pressure Torsion
