Tensile and Compressive Behavior of CHC‐Reinforced Copper using Molecular Dynamics

Abstract

The development of highly tough and ductile metal composites is of particular importance for structural applications, namely in transport industries. There has been ongoing research efforts to harness graphene's outstanding mechanical properties by using it as nanofiller in the mechanical reinforcement of metal nanocomposites, [1][2][3] thus overcoming the typical strength-ductility trade-off. However, graphene's 2D structure brings several processing limitations, such as its tendency to restack and aggregate due to strong van der Waals interactions between layers [4] or low bending rigidity that leads to surface wrinkling, thus delaying a good stress distribution of stresses. [5] One strategy to overcome these limitations is to assemble graphene in 3D networks. [6] Carbon honeycombs (CHC) are novel carbon allotropes that consist in 3D cellular arrangements of graphene nanoribbons connected by sp 3 -hybridized carbon-edge atoms. These graphene nanoribbons form the "walls" of periodic hexagonal cells in a 3D structure that resembles a honeycomb. CHCs were first theorized by Karfunkel and Dressler in 1992, [7] but only in 2016 were they experimentally synthetized by Krainyukova et al. [8] from the deposition of vacuum-sublimated graphite.CHC's unique properties, such as high sorption and storage capacities, [9][10][11][12] membrane sieving, [13] high thermal conductivity, [14][15][16][17] or superior mechanical energy absorbing capacity [18] ), have been predicted mostly by first principles and molecular dynamics (MD) methods. The latter methods were also used to explore in detail the mechanical properties of CHCs.Using first principles, Pang et al. [19] demonstrated that CHCs have high tensile strength depending on cell size and show a marked anisotropic Poisson's ratio effect. They also realized that the honeycomb's stability is related to the combination of sp 2 bonding of graphene nanoribbons with sp 3 carbon bonding in the nanoribbons' junctions.Zhang et al. [20] used density-functional theory (DFT) and MD to study in-plane compressive loading of CHC and found that its mechanical properties are mainly dependent on cell size and on the density of junctions between graphene nanoribbons. They also observed a self-localized deformation behavior in CHC under compression.Gu et al. [21] employed DFT calculations and MD to show that CHCs can have remarkable strength and ductility even for small densities (0.5 g cm À3 ). They calculated strengths as high as

Mechanical Property and Failure Mechanism of Metal Rubber/ZA8 Composite Made by Squeeze Casting Process

“…This phenomenon has earlier been observed in the mechanical performance testing of many metal matrix composites. [ 25,26 ] In turn, the plateau regions in the composites were not clearly observed at a temperature of 25 °C. Additionally, once the strain of the composites approached 30––40%, there was a dramatic drop in stress, indicating a brittle failure of the composites.…”