Young's Modulus Enhancement and Measurement in CNT/Al Nanocomposites

Young’s modulus is a critical parameter for designing lightweight structure, but Al and its alloys only demonstrate a limited value of 70–72 GPa. The introduction of carbon nanotubes(CNTs) is an effective way to make Al and its alloys stiffer. However, little research attention has been paid to Young’s modulus of CNT/Al nanocomposites attributed to the uncertain measurement and unconvincing stiffening effect of CNTs. In this work, improved Young’s modulus of82.4 ± 0.4 GPa has been achieved in 1.5 wt% CNT/Al nanocomposite fabricated by flake powder metallurgy, which was determined by resonance test and 13.5% higher than 72.6 ± 0.64 GPa of Al matrix. A comparative study and statistical analysis further revealed that Young’s modulus determined by tensile test was relatively imprecise(83.1 ± 4.0 GPa) due to the low-stress microplasticity or interface decohesion during tensile deformation of CNT/Al nanocomposite, while the value(98–100 GPa) was highly overestimated by nanoindentation due to the ‘‘pile-up’’ effect. This work shows an in-depth discussion on studying Young’s modulus of CNT/Al nanocomposites.