Investigation of the Effect of Crystallographic Orientation and Non-Rigid Tool on Nickel Hardness in Nanoindentation Process using Molecular Dynamics Simulation

Nickel has great potential for engineering applications in the field of coating and exterior surface due to have good anti-wear and anti-corrosion properties with acceptable strength and ductility. In this study, molecular dynamics simulations of nano-indentation were performed using a single crystal of Nickel with the hemispherical shape of diamond tip. The substrate of workpiece and indenter was modelled using hybrid interatomic potentials including two-body and many-body potentials. Result of derived hardness in various indenter depths was validated with another research paper. At the atomic scale, the crystal structure has directional properties. When nanoindentation of one atomic layer is completed and it is the turn of the next layer, the mechanism of deformation, tip force and hardness can be changed. So in this paper, the effect of crystallography orientation was studied. According to the results, nickel at the crystalline surface (111) had the maximum hardness at depth of 1.5 nm. Also, simulations were conducted with rigid and non-rigid indenters to study the effect of tool deformation on derived hardness. The results show that due to the lack of change in the rigid shape of the tool, the tip force increased by 6.4% in nickel single crystal. Furthermore, due to the decrease of contact level and increase tip force, the hardness increased up to 3.6% in rigid tool compared with non-rigid indenter.