Effect of carbon nanotube (CNT) content on the properties of in-situ synthesis CNT reinforced Al composites

Carbon nanotube (CNT) reinforced Al matrix composites were produced by a modified powder metallurgy route, including in-situ synthesis of CNTs on Al powders by chemical vapor deposition and subsequent ball-milling process. The influence of CNT content (0-4.5 wt%) on the microstructure, mechanical and coefficient of thermal expansion (CTE) performance of CNT/Al composites was systematicly investigated. During the fabrication process, well dispersed CNTs with integrated structure are deeply embedded in Al matrix to form an effective interface bonding. The hardness and tensile strength of CNT/Al composites monotonically increase with the increment of CNT content. The 4.5 wt%-CNT/Al composites exhibit largest hardness and tensile strength, which is 2.3 and 2.4 times higher than that of starting Al, respectively. The CTEs of the composites decrease with the increase of CNT content at the temperature range of 100-300 °C. The CTE of the 4.5 wt%-CNT/Al composites reduces as much as 17% compared with that of starting Al at 100 °C. Thus, we offer a large variety of mechanical and CTE properties which depend on the CNT content in CNT/Al composites, all of them might be good alternatives depending on the application purpose.