An Atomistic Investigation of the Mechanical Behavior of Aluminum Matrix Composites Reinforced by Intragranular and Intergranular Carbon Nanotubes

Abstract

Due to the remarkable low density and high strength of carbon nanotube (CNT) reinforced aluminum composites (CNT/Al composites) have been reported extensively with advanced mechanical properties. However, the distinct roles of intergranular and intragranular CNTs in strengthening the composites remain barely explored, primarily due to challenges in direct experimental observation. In this study, molecular dynamics (MD) simulations were used to investigate the mechanical behavior of CNT/Al composites, focusing on the unique impacts of intragranular and intergranular CNTs. The effect of CNT size on mechanical properties was also assessed. Results revealed that intragranular CNT reinforced aluminum composite exhibited higher peak stress than intergranular case, which can be attributed to the structurally weaker effect of overlapped grain boundary (GB) and embedded CNT in the intergranular model. Additionally, the CNT size would change the peak stress of the composite but not vary the loading bearing mechanism. Irrespective of CNT sizes, intergranular CNT reinforced cases have lower peak stress with earlier void formation than intragranular cases at the same CNT sizes. These findings offer valuable insights into the reinforcement mechanism of intragranular and intergranular CNTs, and provide significant guidance for the structural and processing design of CNT/Al composites, contributing to further continuum model development.

Keywords: Mechanical Behavior, Carbon reinforced Al composite, molecular dynamics, Intragranular, Intergranular