Mechanical behaviors of nanocrystalline Cu/SiC composites: An atomistic investigation
YG Zhou and M Hu, COMPUTATIONAL MATERIALS SCIENCE, 129, 129-136 (2017).
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 x 109 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, 034 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 decent plasticity of metal matrix composites (MMC) also Works at the nanoscale. A sharp increase of strength is found for the SiC/Cu nanocomposites when the SiC VF is around 0.34 due to the switch of the deformation and failure mechanisms. Based on these investigations, we can design the nanocomposite with quite high strength and relatively good plasticity. (C) 2016 Elsevier B.V. All rights reserved.
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