Nanoindentation in alumina coated Al: Molecular dynamics simulations and experiments

HT Luu and S Raumel and F Dencker and M Wurz and N Merkert, SURFACE & COATINGS TECHNOLOGY, 437, 128342 (2022).

DOI: 10.1016/j.surfcoat.2022.128342

Oxygen is often a significant disruptive factor in many production engineering processes and efforts have been made to limit or remove these oxide layers during manufacturing. However, the mechanical properties of oxide layers and their relationship to the raw material are not yet fully understood. In this work, we examine the nanoindentation process on Al surfaces covered with a native oxide layer of various thicknesses using molecular dynamics (MD) models and experiments. For MD simulations, the most advanced interatomic potentials, COMB3 and ReaxFF, are employed to model the interaction between Al and O elements. The two potentials were thoroughly tested and compared with the Embedded Atom Method (EAM). According to our findings, the oxide layer has a significant impact on defect emission in the substrate. However, the behavior of the oxide layer during the indentation process is different for the two potentials. In agreement with experiments, the COMB3 potential shows crack initiation and propagation. The ReaxFF potential displays a pile-up of atoms surrounding the indenter, but no cracks are visible.

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