Mechanical behaviors of nanocrystalline Cu/SiC composites: An atomistic investigation

Abstract

Large-scale molecular dynamic (MD) simulations are employed to investigate the mechanical properties of the nanocrystalline Cu/SiC composites. The MD results indicate that the mechanical behaviors are insensitive to the strain rate when the strain rate is below 1.0×10 9 s-1. The Young's modulus and the yield stress of the nanocomposites increase nonlinearly with the volume fraction (VF) of SiC. Furthermore, the Young's modulus obtained by MD simulations fit the theoretical results well. In addition, a critical volume fraction (CVF) of the SiC reinforcement, 0.34 is obtained. Below the CVF, the nanocrystalline composites show metal-like mechanical behaviors. The majority of the dislocations nucleate at the Cu/Cu and Cu/SiC interfaces and then propagate into the Cu matrix. The flow stress almost keeps constant with the increase of strain. When the VF of reinforcement is above CVF, the reinforcement SiC dominates the mechanical behaviors of the nanocomposites. The strain hardening becomes more obvious with the rise of VF of SiC. Cracks prefer to nucleate and propagate along the SiC/SiC and Cu/SiC interfaces due to their strong brittleness. Our results show that adding the reinforcement to obtain high strength and

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“…For the interaction of Cu–Cu, the embedded atom method (EAM) potential was used. 27–32 For the EAM potential, the total energy of the atomic system E is expressed as where Φij is the pair potential between atom i and atom j , the embedded energy Fi of atom i, and ρi is the electron density of atom i .…”

“…5,28,33,34 Hence, the Tersoff potential was used to describe the interaction between the diamond atoms in these simulations. 27,29–32,35 The Tersoff potential can be expressed as follows where E is the site energy, Vij is the potential energy between atoms, rij is the distance between atoms, θ is the bond angle between the bonds, fR represents a repulsive pair potential, fA represents an attractive pair potential, fc the cut-off function, and ζij represents the number of other bonds to atoms i .…”

“…For the interaction of Cu-Cu, the embedded atom method (EAM) potential was used. [27][28][29][30][31][32] For the EAM potential, the total energy of the atomic system E is expressed as…”

“…5,28,33,34 Hence, the Tersoff potential was used to describe the interaction between the diamond atoms in these simulations. 27,[29][30][31][32]35 The Tersoff potential can be expressed as follows…”

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