Atomistic processes of dislocation generation and plastic deformation during nanoindentation

Begau, Christoph; Hartmaier, Alexander; George, E.P.; Pharr, George M.

doi:10.1016/j.actamat.2010.10.016

Cited by 144 publications

(82 citation statements)

References 19 publications

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“…The interaction between the probe and the samples is represented by a strong repulsive potential. 26 During nanoscratching, the probe first penetrates into the Cu sample by 1.39 nm along the negative Y direction at a constant velocity of 20 m/s, and then scratches 12.22 nm along the negative X direction at a constant velocity of 20 m/s. Figure 1(g) illustrates the scratching process.…”

Section: Simulation Methodsmentioning

confidence: 99%

Twin boundary spacing-dependent friction in nanotwinned copper

et al. 2012

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The deformation mechanisms of nanotwinned Cu subjected to nanoscratching are investigated by means of molecular dynamics simulations. Scratching simulations on nanotwinned single-crystalline Cu with the twin planes parallel and perpendicular to the scratching direction are performed. Since the detwinning mechanism is completely suppressed in the former case, no apparent correlation between frictional coefficient and the twin spacing is observed. In samples where the twin planes are perpendicular to the scratching direction, the friction increases as the twin spacing decreases, and then decreases as the twin spacings become even smaller. It results from the competitive plastic deformation between the inclined dislocations and the detwinning mechanism. Subsequent simulations for nanotwinned polycrystalline Cu unveil that in addition to the grainboundary-associated deformation mechanism, dislocation-mediated detwinning plays a significant role in the plastic deformation of nanotwinned Cu. The twin boundary spacing in turn affects nanotwinned materials to resist scratching via plastic deformation. We demonstrate via the nanoscratching tests that there exists a critical twin boundary spacing for which the friction coefficient is maximized and that this transition results from the competing deformation mechanisms in those nanotwinned materials.

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Section: Simulation Methodsmentioning

confidence: 99%

Twin boundary spacing-dependent friction in nanotwinned copper

et al. 2012

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“…Furthermore, this tool combines Nye-tensor analysis for Burgers vector identification [24,25] and dislocation skeletonization. [26] For complementary analysis, the centrosymmetry parameter (CSP) as well as the coordination number for binary systems were used. See the supplementary material at http://dx.doi.org/10.1080/21663831.…”

Section: Methodsmentioning

confidence: 99%

Atomistic Simulations of Compression Tests on Ni₃Al Nanocubes

Amodeo

Begau

Bitzek

2014

Materials Research Letters

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Supplementary Material Available OnlineThe deformation behaviour of nano-sized Ni 3 Al cubes with {100} side surfaces is investigated under uniaxial compression using constant-temperature molecular dynamics simulations at 300 K. The simulations reproduce key features of recently performed nanocompression experiments, namely the lack of strain hardening, homogeneous deformation of the entire sample and overall high stress levels of the order of 3-5 GPa. According to the simulations, the critical initial step is the formation of a pseudo-twin structure, which then further deforms by Shockley partial dislocations. These deformation mechanisms differ significantly from bulk Ni 3 Al and are rationalized in terms of generalized stacking fault energies and resolved shear stresses.

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“…Compared to face centered cubic (FCC) systems, where the correlation between incipient plasticity and dislocation motion has been well established [5,6,8,[14][15][16][17][18][20][21][22]. BCC systems are much more complex and, despite several reports [11][12][13][23][24][25][26][27][28][29], there are still many unanswered questions regarding our understanding of BCC-plasticity in nanocontacts encountered in indentation.…”

Section: Introductionmentioning

confidence: 99%

“…However, atomistic simulations showed that the homogeneous dislocation nucleation assumption might not be true and that dislocations can in fact nucleate heterogeneously [17] or by completely different mechanisms such as twinning [19]. Compared to face centered cubic (FCC) systems, where the correlation between incipient plasticity and dislocation motion has been well established [5,6,8,[14][15][16][17][18][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

“…The strength of this technique lies in its ability to probe ultra-small and therefore virtually "defect-free" sample volumes. In well-prepared surfaces of single crystals, this leads to the appearance of discontinuities in the loaddisplacement curves that are generally explained by homogeneous nucleation of dislocations loops in the area of maximum stress underneath the indenter [14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

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