Insights into the fracture mechanisms and strength of amorphous and nanocomposite carbon

TL;DR

This study uses molecular dynamics simulations to explore how amorphous and nanocomposite carbon materials fracture and their strength, revealing that nanodiamond inclusions improve elastic properties while fracture occurs at weak bonds.

Contribution

It provides new insights into the fracture mechanisms and strength of amorphous and nanocomposite carbon, highlighting the role of nanodiamond inclusions and bond weaknesses.

Findings

Fracture occurs at weakly bonded sp^3 sites in the amorphous matrix.

Nanodiamond inclusions significantly increase elastic moduli.

Ideal strength of nanocomposites is similar to that of pure amorphous carbon.

Abstract

Tight-binding molecular dynamics simulations shed light into the fracture mechanisms and the ideal strength of tetrahedral amorphous carbon and of nanocomposite carbon containing diamond crystallites, two of the hardest materials. It is found that fracture in the nanocomposites, under tensile or shear load, occurs inter-grain and so their ideal strength is similar to the pure amorphous phase. The onset of fracture takes place at weakly bonded sp^3 sites in the amorphous matrix. On the other hand, the nanodiamond inclusions significantly enhance the elastic moduli, which approach those of diamond.