Multi-scale analysis of nanoscale contact process between spherical indenter and single crystal aluminium

Based on the quasicontinuum method and repulsive force-field approach, a muti-scale modeling of nano-contact process between rigid spherical indenter and surface of single crystal aluminium is established. The corresponding load-depth, graph of atomic state, and moire pattern of displacement are obtained, from which the arrangement of atoms and the effects of the shape of indenter on the nucleation and emission of dislocations in the contact process are studied. Therefore micro-mechanisms of deformation are analyzed. The result shows that due to the fact that the direction of force on atoms that contact the indenter is constantly changing with the increase of contact depth, the corresponding load-depth shows that step increases which is different from that of the square indenter with the response of the underlying crystal. Due to the indenter geometry, the close packed planes under both sides of indenter slip partially lead to Shockley partial dislocations. In the process of disengagement, the elastic recovery is accomplished as the atoms move up with indenter. The residual depth is 0.3 nm, which is close to the magnitude of the Burgers vector, 0.285 nm.