Molecular Dynamics Study on Dislocation Nucleation from a Stepped Coating on a Face-Centered Cubic Metal and Evolution of Surface Microplasticity
MAI Trong Nghia
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Crystal surfaces are commonly coated by another material for engineering applications. Even though, these coating layers are repaired perfectly, there exists some nanoscale roughness on its surface. Nanoscale asperities of material surfaces may play a key role in the evolution of surface plasticity through dislocation activities under frictional contact loadings. In this study, atomistic simulation with the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) was performed for the adhesive contact of a grid flat indenter on a coating film on a face-centered cubic copper crystal, in which nanoscale roughness was modeled with a surface step. The atomic interaction between the flat indenter and the coating film was modeled with Lennard-Jones potential, of which parameters was varied to tailor the adhesion energy between the flat indenter and the coating film. Besides, Lennard-Jones potential was also used for the artificial coating film in order to simulate varied material by changing Lennard-Jones parameters. As the indenter is compressed against the coating film with a surface step, dislocations are nucleated from the step and emitted into the copper substrate. In this study, the effect of protecting coatings on dislocation nucleation is studied by means of molecular dynamics approach.