Molecular dynamics of monocrystal copper nano-scratched with tungsten tip

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The utilization of ultra-sharp tungsten tips for nano-scratching has been employed in the fabrication of copper micro/nanostructures. Understanding the material removal mechanisms and the evolution of subsurface defects during this process is crucial for optimizing manufacturing processes. Nevertheless, the mechanisms of material removal and subsurface defect evolution of ultra-sharp tungsten tips nano-scratching monocrystal copper remain elusive. This study utilizes molecular dynamics simulation to investigate the material removal mechanism, subsurface defect, and dislocation evolution of monocrystal copper nano-scratched with tungsten tip. Furthermore, the formation mechanism of stress-induced stacking faults is revealed through spatially distributed hydrostatic pressure analysis. Finally, the effect of scratching parameters on subsurface damage and workpiece machinability is explored. The results indicate that plastic deformation mechanisms of nano-scratching monocrystal copper include amorphization, dislocation slip, and atomic phase transition. During the nano-scratching process, V-shaped dislocation loops and prismatic dislocation loops are formed in the shearing-plowing region, and atomic clusters and stacked fault tetrahedrons are generated in the subsurface region. Scratching along the [100] crystal orientation, coupled with relatively increased scratching distance, velocity, and appropriate depth facilitates the attainment of shallow subsurface deformed layer and excellent machinability.