Al-matrix composites reinforced with amino-functionalized multiwalled carbon nanotubes (fall's) have been fabricated using the powder metallurgy process. Using this method fCNTs (1.5 wt.%) were dispersed in Al powder by high energy ball milling. Al-fCNTs composites (1.5 wt.%) were fabricated by the consolidation of powders at 550 MPa followed by sintering at 620 degrees C under a vacuum of 10(-2) Torr for 2 h. Functionalization of the nanotubes was carried out by ball milling multi-walled carbon nanotubes (MWCNTs) in the presence of ammonium bicarbonate. It was observed that the dispersion of fCNTs in Al-matrix was much higher than those of non-functionalized MWCNTs. Microhardness measurements showed that a microhardness value of about 400 kg/mm(2) could be obtained for Al-matrix composites loaded with 1.5 wt.% fCNTs. Microstructure observations using scanning electron microscopy (SEM) and high-resolution electron microscopy (HRTEM) confirmed that the sintered composites had a good dispersion of fCNTs in Al matrix and they do not agglomerate with each other. Further, the HRTEM characterization of these composites revealed the formation of a thin transition layer of Al4C3 between fCNTs and Al matrix, which is believed to be responsible for load transfer from Al matrix to fCNTs. A thorough characterization of MWCNTs and fCNTs synthesized in the present work was carried out using XRD, SEM, TGA, HRTEM, FTIR, SIMS and Raman spectroscopy. (C) 2011 Elsevier B.V. All rights reserved.