Molecular dynamics simulation of nanoscale contact and sliding processes for probes with different tip radius of curvature

Three-dimensional molecular dynamics (MD) simulations were carried out to study the contact and sliding processes between diamond points with different tip radius of curvature and surfaces of single crystal copper. The material deformation, abrasion mechanism, lattice defects, the force of contact process, and the sliding friction process were investigated. The simulation results show that the contact force, dislocations, and stacking fault defects, increase during the contact process with increasing contact depth or tip radius of curvature. The dislocations emit along the $ \left {10\bar{1}} \right] $ and $ \left {\bar{1}0\bar{1}} \right] $ direction and then a glide band is formed. It was also found that a greater tip radius of curvature results in a larger groove and more material deformation. The normal force and friction increase with increasing tip radius of curvature, but the coefficient of friction decreases. The stacking faults spread along the sliding direction and increase with increasing tip radius of curvature. In addition, the number of upheaval atoms increases as the radius of tip curvature or sliding distance increases.