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Atomistic Study of Iinterface Properties and Structure of Nickel-Silicon and Polyethelene-Ghraphene by Molecular Dynamics Simulation

Amini, Hamed | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42970 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Kokabi, Amir Hossein; Simchi, Abdolreza
  7. Abstract:
  8. First atomistic simulation was used to study the deformation and fracture mechanisms of Ni-Si interfaces under tensile and shear loads dependent on the crystal structure of interface zone. Modified embedded atom method (MEAM) potential was utilized for molecular dynamics (MD) modeling. The simulation includes analysis of common neighbors, coordination number, least-square atomic local strain, and radial distribution function. The profound effect of interface crystallography on the tensile and shear deformation is shown. The highest tensile strength is obtained for interfaces with high plane density due to lowest atomic disorder while under shear loading planes with low density exhibit a high local deformation as a result of regional atomic amorphization. The deformation mechanism in shear mode is shown to be controlled by planner sliding and local amorphization at the interface zone. A general agreement between the strength and atomic planar density at the interface is demonstrated. Next, mechanical properties of polyethelene-ghraphene was studied. Initial polymer configuration was generated as random by self avoiding random walk algorithm. Tensile and pull-out simulations for samples with difference polymer lengths was carry out. Results of tensile simulation along ghraphene sheet demonstrated that length of polymer doesn’t have effect on strength. However the polymer length have dramatic effect on tensile simulation perpendular ghraphene sheets. Also bond strength is increased with reduction of polymer length in pull-out simulations.
  9. Keywords:
  10. Molecular Dynamic Simulation ; Interfaces ; Deformation ; Nickel-Silicon ; Crystalline Structure ; Polyethylene-Graphene

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