A comprehensive analysis of mechanical characteristics of carbon nanotube-metal matrix nanocomposites

Founding structure-property relationships for metal matrix nanocomposites containing carbon nanotubes (CNTs) is a fundamental task for a reliable design of such new materials. An analytical model is presented to predict the elastic modulus, yield strength and ultimate tensile strength of CNT-aluminum (Al) nanocomposites. The influences of volume fraction, diameter, length, non-straight shape, coefficient of thermal expansion (CTE) and dispersion type of CNTs into the Al metal matrix on the overall mechanical behavior of nanocomposites are examined. Additionally, the effects of mechanical properties of Al matrix and temperature change on both the yield strength and ultimate tensile strength are explored. Generally, a good agreement is observed between the results of the present model and available experiment. The results obviously reveal that for a more realistic prediction in the case of ultimate tensile strength of CNT/Al nanocomposites, considering the non-straight shape of CNTs, mismatch in CNT/Al CTEs and Orowan strengthening mechanism is essential. Also, a more accurate estimation of yield strength of CNT-Al nanocomposites is accessible when both the effects of non-straight shape of CNTs and mismatch in CNT/Al CTEs are considered in the analysis. The predicted elastic modulus of Al nanocomposites considering non-straight shape of CNTs is much closer to the experiment as compared with that of Al nanocomposites considering straight shape of CNTs. Using the aligned CNTs into the metal matrix with a (i) higher volume fraction, (ii) lower diameter, (iii) higher length, (iv) lower CTE and (v) straight shape can lead to an improvement in the mechanical properties of CNT-reinforced metal matrix nanocomposites.