Unveiling the local deformation behavior of typical microstructures of nickel-based single crystals under nanoindentation

Abstract

In the present study, consider the typical microstructures (γ, γ’ and interface phases) in nickel-based single crystal, three ideal simplified atomic models of Ni, Ni3Al and Ni/Ni3Al interface were established. And nanoindentation molecular dynamics (MD) simulations were performed on the above models. Based on the dynamic deformation behavior and mechanism of nickel-based single crystal microstructure under the local loading, the nanoindentation plastic deformation is divided into two stages Pi and Pii. In the initial Pi stage, dislocations only move and react on the contact surface between the indenter and the substrate. Subsequently, in stage Pii, edge dislocations climb away from the contact surface, screw dislocations interact with each other and finally form dislocation shear loops. The local plastic deformation is dominated by the nucleation and emission of dislocation loops, affected by its resistance and dislocation velocity. It is noted that in the interface model, dislocation shear loops inevitably interact with interface dislocations, which will lead to further plastic deformation. Combined with the dislocation theory and the above research, a model based on the movement of dislocations was established better describe the local plastic behavior of the typical microstructure in nickel-based single crystal under indentation.