Architectural and component design of CNTs/Al hierarchical composite for enhanced mechanical/thermal properties

Abstract

This study aims to fabricate heterogeneous CNTs/Al composites with a hierarchical structure using powder metallurgy techniques. The hierarchical composites are composed of alternating layers with and without CNTs. Tensile testing of the as-sintered sample, with a 3.5 mm width and containing 0.5 wt% CNTs, revealed an ultimate tensile strength of 249 MPa and 11.8 % elongation to failure. This shows an improvement in overall mechanical properties while maintaining the superior ductility of the alloy and the high strength of uniform composites. Indicating an effective overcoming of the traditional trade-off between strength and ductility. Several strengthening mechanisms have been discussed, including load transfer, grain refinement, and extra dislocations. Coordinated deformation and retarding effect during crack propagation can significantly enhance ductility. Furthermore, the incorporation of reinforcement increased the thermal conductivity by 18.6% due to the excellent thermal characteristics of CNTs. To investigate the intrinsic principles, a parallel and series model was developed to simulate the arrangement of CNTs in the Al matrix. Molecular dynamics (MD) simulations revealed the heat transfer mechanism through the electron-phonon coupling effect. This study proposes a new approach for creating metal materials that have both strength and ductility, while also improving their thermal conductivity.

Keywords

• Carbon nanotubes
• Hierarchical composites
• Mechanical property
• Thermal conductivity