Nanoindentation size effect in single-crystal nanoparticles and thin films: A comparative experimental and simulation study

Depinning-controlled plastic deformation during nanoindentation of BCC iron thin films and nanoparticles

“…For the Mendelev EAM potential, the parameter a = 0.33r c was found to reproduce the value for the interface energy Fe/Sapphire. A similar approach was adapted for FCC nanoparticles and for further information on how to adjust the potential at the interface, we refer reader to [12]. To summarize, the nanoparticle shape, based upon the relaxed surface energies and the interface energy, is shown in Fig.…”

“…It was found that the indentation force measured during indentation of Au nanoparticles depends strongly on their size and all nanoparticles are softer than thin-films of the same height [12]. It is suggested that dislocations are nucleated beneath the tip, but due to the small lateral dimensions of the specimen, they instantly depin themselves and deplete on the lateral free surface.…”

“…Traditionally, this experimental technique is commonly employed to calculate the hardness and elastic moduli of materials (see [5] and references therein). However, at the sub-micrometer scale it allows also studying how dimensionality affects the plastic deformation [6][7][8][9][10][11][12][13]. At these scales, the key to understanding the mechanical response is the comprehension of the dislocation mechanisms acting during indentation and their interaction with the specimen's surface (e.g.…”

“…This leads us to the question if the different dislocation mechanisms in BCC metals may give rise to different characteristics of the indentation response of small-scale specimens. While a detailed analysis of the importance of dimensionality on the dislocation mechanisms during indentation of FCC metals was performed in [12], we examine here how a-Fe (BCC) nanoparticles and thin-films deform during indentation, with an eye toward the effect of size on the indentation curve. In particular, we inspect if the free surfaces play a similar role as in the case of FCC specimens.…”

“…At these scales, the key to understanding the mechanical response is the comprehension of the dislocation mechanisms acting during indentation and their interaction with the specimen's surface (e.g. [10][11][12][13]). Nonetheless, in addition to the difficulty in quantitatively analyzing the deformation during indentation, experiments alone rarely provide insights on the underlying microstructural mechanisms that control the plastic deformation.…”