Dual strengthening mechanisms induced by carbon nanotubes in roll bonded aluminum composites

The dual role of carbon nanotubes (CNTs) in strengthening roll bonded aluminum composites has been elucidated in this study. An increase in the elastic modulus by 59% has been observed at 2 vol.% CNT addition in aluminum, whereas tensile strength increases by 250% with 9.5 vol.% CNT addition. CNTs play a dual role in the strengthening mechanism in Al-CNT composite foil, which can be correlated to the degree of dispersion of CNTs in the matrix. Better CNT dispersion leads to improvement of elastic properties. In contrast, CNT clusters in the aluminum matrix impede dislocation motion, causing strain hardening and thus improvement in the tensile strength. Dislocation density of the composites has been computed as a function of CNT content to show the effect on strain hardening of the metal matrix-CNT composite. (C) 2009 Elsevier B.V. All rights reserved.