Nanoindentation and nanotribology behaviors of open-cell metallic glass nanofoams

YH Zhang and JF Xu and YQ Hu and SH Ding and WW Wu and R Xia, INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, 249, 108254 (2023).

DOI: 10.1016/j.ijmecsci.2023.108254

An in-depth understanding of the mechanical properties of metallic glass nanofoams (MGNFs) is critical to their potential multifunctional applications. In this work, the mechanical properties of Cu50Zr50 open- cell MGNFs are investigated via nanoindentation and nanotribology techniques through virtual molecular dynamics simulations, and the effects of structural parameters (relative density and specific surface area) and loading conditions are studied. The intriguing deformation mechanisms of MGNFs during nanoindentation and nanotribology processes are revealed. It is found that the relationship between indentation modulus and relative density of MGNFs obeys the classical Gibon-Ashby prediction of the bending-dominating porous structure. The hardness of MGNFs monotonously increases with increasing relative density. Differently, as the specific surface area rises, the hardness first increases to its maximum and then decreases. During nanotribology, the MGNFs exhibit relatively steady tribology performance. After being scratched, atoms are pressed into the workpiece surface. In the whole tribology process, no chips or wear debris form. This absence of chips and wear debris effectively avoids the enhancement of frictional force, stabilizing the tribology responses. Von Mises shear strain and Voronoi cluster analysis demonstrate that structural damage is more dramatic for samples having larger relative densities or larger specific surface areas during both indentation and tribology processes. The localized deformation and the surface effect cause more severe damage for larger relative densities and larger specific surface areas, respec-tively. This study clarifies the essential mechanical properties and deformation mechanisms of MGNFs under nanoindentation and nanotribology loads.

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