Effect of Carbon Nanotubes as Reinforcement on the Mechanical Properties of Aluminum-Copper-Magnesium Alloy

Elemental powders of Al, Cu, Mg and x wt.% CNT (x: 0-2.5) were blended and milled in the high-energy ball mill for 4 h. Milled powders of Al alloy-CNT composites were subsequently consolidated by upset forging followed by hot extrusion. Even though the particle size of milled powders of Al alloy-CNT composites decreased with the addition of CNT, there is no significant effect on crystallite size. Raman spectra indicated that the nanocrystalline structure of CNT is retained after milling. Yield and ultimate tensile strengths increased with CNT content and Al alloy-2.5 wt.% CNT exhibited an enhancement of 56 and 73%, respectively, when compared to Al alloy in solutionized condition. The improvement in mechanical properties of Al alloy-CNT composites is due to ultra-fine grain size, finer second-phase precipitates and uniform dispersion of CNT.