Microstructural evolution and mechanical properties of multiwalled carbon nanotubes/Al6082 nanocomposites through optimized T6 heat treatment process

Abstract

A modified stir casting method was used to fabricate novel Al6082 composites reinforced with 0, 0.3, 0.6, 0.9, and 1.2 wt% of multiwalled carbon nanotubes (MWCNTs). A field emission scanning electron microscope was used to examine the microstructure, while elemental evaluation was performed with an energy dispersive X-ray spectrometer. MWCNTs/Al6082 composites were subjected to a heat treatment cycle (T6) to enhance their mechanical strength. Mechanical alloying and ultrasonication enhanced the wettability during fabrication resulting in the uniform distribution of MWCNTs up to 0.9 wt%. Ultimate tensile strength, yield strength, and hardness of 0.9 wt% MWCNTs/Al6082 nanocomposites were enhanced over Al6082 alloy by 41.94%, 40.73%, and 42.97% at the as-cast condition and 76.96%, 81.61%, and 64.62% at peak-aged condition, respectively. Furthermore, nanocomposite fractography represented a mixture of ductile and brittle fracture for 0.3 wt% MWCNTs and brittle fracture for further addition of MWCNTs.