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In this paper, we employed molecular dynamics (MD) simulations to model the nanoindentation process, aiming to explore the mechanical characteristics of a silver (Ag) coating film on a copper (Cu) substrate. Three distinct bilayer configurations were selected, namely Ag (100)/Cu (111), Ag (110)/Cu (111), and Ag (111)/Cu (111), with the purpose of examining the impact of heterogeneous interfaces on deformation behaviors during nanoindentation. The results demonstrate that the Ag (111)/Cu (111) bilayer exhibits a higher force during the nanoindentation process when compared to the Ag (100)/Cu (111) and Ag (110)/Cu (111) bilayers. This suggests that interfaces with a smaller mismatch in the specified crystal plane between Ag and Cu are proven to be harder. To studied the correlation between indentation velocity and the interface, we considered various values of indentation velocities ranging from 120 m/s to 200 m/s, conducting indentations on the Ag (111)/Cu (111) bilayer. The findings indicate that variations in indentation velocity significantly impact the mechanical properties of Ag (111)/Cu (111) bilayers. Both force and hardness values exhibit a significant increase as indentation velocity rises, implying that the strength of Ag/Cu bilayers is more pronounced at higher indentation velocities. These observed trends were attributed to defect and dislocation formation at the interface, as confirmed through dislocation extraction analysis (DXA). [ABSTRACT FROM AUTHOR]

Nanoindentation has been utilized to investigate the variations of the interatomic distances in both the initial and bulk states of the β-Al3Mg2, e-Al30Mg23 and γ-Al12Mg17 phases. This technique has enabled the identification of the properties of these phases throughout the process. Continuing previous nanoindentation simulations conducted on the same phases [1], this study aims to further understand the behavior of these materials under molecular dynamics along the [001] direction. A proportional relationship between the applied load and atomic displacement affects the pair-wise distance, depth, and penetration amplitude for the three phases. Among them, the ε-Al30Mg23 phase demonstrated the greatest depth and amplitude of deformation compared to the β-Al3Mg2 and γ-Al12Mg17 phases. Interatomic distances between Mg-Mg, Mg-Al, and Al-Al in the three phases indicate a transition from an ordered crystalline structure to a more energetic disordered structure. These behaviors vary among the phases. To characterize the phase structures, a common neighbor analysis was employed. It was found that in the β-Al3Mg2 phase, the Al-Mg atoms are arranged within face-centered cubic (fcc), hexagonal close-packed (hcp), icosahedral (ico), and structure of type other. The ε-Al30Mg23 phase is primarily arranged in icosahedral and other unspecified structures. Meanwhile, the γ-Al12Mg17 phase is arranged in body-centered cubic (bcc), icosahedral, and structure of type other. [ABSTRACT FROM AUTHOR]

This research aims to investigate the deformation mechanisms and mechanical response of a Nb/Cu bilayer thin film under nanoindentation using molecular dynamics (MD) simulations. The specific objectives of this study are to explore the impact of indentation velocity ranging from 10 to 150 m/s on defect formation and hardness, and to understand the correlation between deformation behavior and loading rate. The hypothesis is that lower indentation velocities will result in a load-displacement curve with an initial linear region indicating elastic deformation, while higher velocities will produce a serrated profile, indicating plastic behavior. The relative hardness of the Nb/Cu sample is expected to vary with increasing velocity from 10 m/s to 50 m/s until reaching a certain threshold, beyond which it may increase due to enhanced strain hardening effects. Additionally, the load-displacement curves may show load drops corresponding to specific indentation depths. These drops could be attributed to the occurrence of defects such as atomic rearrangements or dislocation nucleation at critical depths. Analyzing these phenomena will provide valuable insights into the nanoscalemechanical properties of Nb/Cu bilayer thin films and their relationship with indentation velocities. [ABSTRACT FROM AUTHOR]