Fivefold enhancement of yield and toughness of copper nanowires via coating carbon nanotubes.

Carbon nanotubes are outstanding reinforcements owing to their unparallel strength, while their effects on the copper nanowire are still not fully understood, hampering their broad applications. Herein, we have investigated the tensile behaviors of the nanocomposite-wire of carbon nanotube-copper using molecular dynamic simulations. For the nanocomposite, both the coated and embedded carbon nanotubes increase the Young's modulus, fracture stress and toughness of the copper nanowire. A reinforcement of over fivefold in both yield strength (5.3 times) and toughness (5.1 times) has been achieved when the carbon nanotubes are coated on the copper nanowires, as well as 1.7 times in the Young's modulus. Higher temperatures and lower loading rates reduce the reinforcement.

Graphene Surface Reinforcement of Iron.

Graphene is an ideal material in the reinforcement of metal-matrix composites owing to its outstanding mechanical and physical properties. Herein, we have investigated the surface enhancement of iron via a computational nanoindentation process using molecular dynamics simulations. The findings of our study show that graphene can enhance the critical yield strength, hardness and elastic modulus of the composite to different degrees with the change of the number of graphene layers. In the six tested models, the composite with trilayer graphene on the surface produces the strongest reinforcement, with an increased magnitude of 432.1% and 169.5% in the hardness and elastic modulus, respectively, compared with pure iron. Furthermore, it is revealed that high temperature could weaken the elastic bearing capacity of the graphene, resulting in a decrease on the elastic mechanical properties of the graphene/Fe composite.