A Study on Size Effect of Indenter in Nanoindentation via Molecular Dynamics Simulation

A series of three-dimensional molecular dynamics (MD) simulations of nanoindentation are conducted to investigate the deformation behavior and phase transformation of monocrystalline silicon with different size hemispherical diamond indenters on (010) crystal plane. The technique of coordination number (CN) is employed to elucidate the detailed mechanism of phase transformation in the monocrystalline silicon. The simulation results show that the phase transformation varies according to the different radii indenters. In the phase transformation region beneath the indenter, the crystalline structures of Si-II, Si-XIII, and amorphous phase structures are observed. In addition, the results indicate that phase transformation with large indenters is not same with the small indenter. The six-coordinated silicon phase, Si-XIII, transformed from Si-I is identified. The phases of Si-II and Si-XIII, which have the same coordinate number, are successfully extracted from the transformation region during nanoindentation and amorphous phase will emerge upon unloading.