Deformation Mechanism and Strength Behavior of Ag-Ni Bilayer ^†

In this investigation, we utilize molecular dynamics (MD) simulations to model the nanoindentation process, specifically focusing on the deformation mechanism and strength behavior of a Silver (Ag) coating film on a Nickel Ni (111) substrate. Our study examines how both the orientation of Ag film and indentation velocity affect the mechanical properties of the Ag-Ni bilayer. In this simulation, three distinct configurations of Ag film were used: Ag (100), Ag (110), and Ag (111). Our findings reveal that the Ag (111)/Ni (111) bilayer experiences higher forces during the nanoindentation process compared to the Ag (100)/Ni (111) and Ag (110)/Ni (111) bilayers. This observation suggests that interfaces with a smaller mismatch in crystal plane orientation between Ag and Ni exhibit greater hardness. Additionally, we investigate the relationship between indentation velocity and interface properties by considering various indentation velocities (ranging from 90 m/s to 200 m/s) on the Ag (111)/Ni (111) bilayer. Notably, variations in indentation velocity can significantly influence the mechanical properties of the Ag (111)/Ni (111) bilayers. Both force and hardness values exhibit substantial increases as indentation velocity rises, implying that the strength of Ag/Ni bilayers becomes more pronounced at higher indentation velocities. These trends are attributed to defect and dislocation formation at the interface, as confirmed via dislocation extraction analysis (DXA).