Carbyne as a fiber in metal-matrix nanocomposites: A first principle study

Abstract

Abstract Carbyne is a lightweight 1-D carbon allotrope with exceptional mechanical properties, making it an ideal candidate as a fiber in metal-matrix nanocomposites. However, carbyne is also unstable in many environments, which may negatively affect its potential mechanical contributions. In this study, we use density functional theory to predict the maximum local stiffness in a nanocomposite composed of carbyne within a nickel (Ni) matrix. We compute the local specific stiffness of carbyne-Ni from energy-strain relations, allowing us to avoid the ambiguity of volume approximations inherent in materials with less than three dimensions. We use Bader charge analysis to study how charge transfers within the nanocomposite and its effect on local specific stiffness. We find that carbyne enhances the local specific stiffness of carbyne-Ni nanocomposites when it is dielectrically screened from the Ni matrix using graphene sheets, with ∼25% increase in specific stiffness over a graphene-Ni nanocomposite. When carbyne is not dielectrically screened its bond structure breaks down, carbon’s average electronic charge per-atom increases, and there is ∼60% drop in the local specific stiffness compared to the dielectrically screened case.