Molecular dynamics study of the γ/γʹ interface influencing the nano-deformation of nickel-based single crystal alloys during nanoindentation process

To investigate the effect of γ/γʹ interface on the nano-deformation of the workpiece during nanoindentation of nickel-based single crystal alloys, a two-phase model of γ phase doped with Cr and Co elements was simulated using a molecular dynamics approach with controlling the indenter displacement. It is found that: in the early stage of loading, the load increases gradually with the increase of loading depth; when the indenter is close to the interface, the load is affected by the interface and changes abruptly, generating a great value; after the indenter breaks through the interface, the load fluctuates and becomes larger. More Stair-rod dislocations and Hirth dislocations are generated at the interface, and these dislocations, together with some dislocation nodes, strengthen the matrix dislocations to enhance the deformation resistance of the workpiece. In addition, atomic displacement, strain transfer, and defect development are discontinuous during the movement of the γ phase to the γʹ phase. In particular, the displaced atom morphology in the γʹ phase evolves from triangular to filleted corner, reflecting the inhibitory effect of the boundary on the development of the plastic deformation region.