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Abstract: AFM is a powerful and versatile tool which has the ability to fabricate nanoelectronics and other nanoparts using nano-scratching method. To achieve a deeper understanding on AFM-based nano-scratching process, molecular dynamic (MD) simulation approach is employed. Interactive forces between a rigid pyramidal tool simulating an AFM diamond tip and a copper sample are modeled by the Morse function. Two adjacent scratching tests are carried out at different feeds simulating the multiple scratching tests. Effects of the feed on the scratching process are discussed. Results show that the feed has a significant effect on the deformation of the machined surface, the scratching depth, scratching forces and potential energy. The important effect of the relax process in the MD simulation of AFM-based multiple nano-scratching processes is exhibited, which cannot be ignored when analyzing the variation of the potential energy. [Copyright &y& Elsevier]

Abstract: In this paper we report molecular dynamics based atomistic simulations of deposition process of Al atoms onto Cu substrate and following nanoindentation process on that nanostructured material. Effects of incident energy on the morphology of deposited thin film and mechanical property of this nanostructured material are emphasized. The results reveal that the morphology of growing film is layer-by-layer-like at incident energy of 0.1–10eV. The epitaxy mode of film growth is observed at incident energy below 1eV, but film-mixing mode commences when incident energy increase to 10eV accompanying with increased disorder of film structure, which improves quality of deposited thin film. Following indentation studies indicate deposited thin films pose lower stiffness than single crystal Al due to considerable amount of defects existed in them, but Cu substrate is strengthened by the interface generated from lattice mismatch between deposited Al thin film and Cu substrate. [Copyright &y& Elsevier]

Detwinning is a unique deformation mechanism of nanotwinned metals with twin lamellae thickness down to a few nanometers. In this work we investigate the impact of detwinning mechanism on the tensile ductility of twinned Cu nanowires containing high density of parallel twin boundaries by means of molecular dynamics simulations. Simulation results show that the fracture strain of twinned Cu nanowires has a strong dependence on twin boundary spacing, resulting from the competition between individual deformation modes. Particularly for the twinned Cu nanowires containing the thinnest twin lamellaes, the dominant detwinning mechanism leads to a significant reduction in the tensile ductility. It is found that detwinning originates from twin boundary migration, which is a result of the glide of lattice partial dislocations on the twin planes. This work advances our fundamental understanding of the twin boundary-related mechanical properties of twinned metallic nanowires. [ABSTRACT FROM AUTHOR]