Influence of crystal anisotropy on elastic deformation and onset of plasticity in nanoindentation: A simulational study

Ziegenhain, Gerolf; Urbassek, Herbert M.; Hartmaier, Alexander

doi:10.1063/1.3340523

Cited by 144 publications

(87 citation statements)

References 29 publications

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“…The contact pressure defined as the ratio of the penetration force to the contact area is further calculated. A detailed description about the calculation of the contact area during spherical penetration can be found elsewhere [45]. Figure 2(a) plots the contact pressure versus penetration depth curves of penetration on the NT Cu samples containing parallel TBs.…”

Section: Effect Of Crystallographic Orientationmentioning

confidence: 99%

Mechanisms of anisotropic friction in nanotwinned Cu revealed by atomistic simulations

Zhang

Hartmaier

Wei

et al. 2013

Modelling Simul. Mater. Sci. Eng.

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The nature of nanocrystalline materials determines that their deformation at the grain level relies on the orientation of individual grains. In this work, we investigate the anisotropic response of nanotwinned Cu to frictional contacts during nanoscratching by means of molecular dynamics simulations. Nanotwinned Cu samples containing embedded twin boundaries parallel, inclined and perpendicular to scratching surfaces are adopted to address the effects of crystallographic orientation and inclination angle of aligned twin boundaries cutting the scratching surface. The transition in deformation mechanisms, the evolution of friction coefficients and the friction-induced microstructural changes are analyzed in detail and are related to the loading conditions and the twinned microstructures of the materials. Furthermore, the effect of twin spacing on the frictional behavior of Cu samples is studied. Our simulation results show that the crystallographic orientation strongly influences the frictional response in different ways for samples with different twin spacing, because the dominant deformation mode varies upon scratching regions of different orientations. A critical inclination angle of 26.6• gives the lowest yield strength and the highest friction coefficient, at which the plasticity is dominated by twin boundary migration and detwinning. It is demonstrated that the anisotropic frictional response of nanotwinned Cu originates from the heterogeneous localized deformation, which is strongly influenced by crystallographic orientation, twin boundary orientation and loading condition.

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Section: Effect Of Crystallographic Orientationmentioning

confidence: 99%

Mechanisms of anisotropic friction in nanotwinned Cu revealed by atomistic simulations

Zhang

Hartmaier

Wei

et al. 2013

Modelling Simul. Mater. Sci. Eng.

View full text Add to dashboard Cite

show abstract

“…The values of A ind p were determined during the MD simulation following the procedure proposed in Refs. [22,35]. In this approach, only atoms lying within the spherical shell of radius R ?…”

Section: Indentation Stagementioning

confidence: 99%

Atomistic Insights on the Wear/Friction Behavior of Nanocrystalline Ferrite During Nanoscratching as Revealed by Molecular Dynamics

et al. 2017

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Using embedded atom method potential, extensive large-scale molecular dynamics (MD) simulations of nanoindentation/nanoscratching of nanocrystalline (nc) iron have been carried out to explore grain size dependence of wear response. MD results show no clear dependence of the frictional and normal forces on the grain size, and the single-crystal (sc) iron has higher frictional and normal force compared to nc-samples. For all samples, the dislocation-mediated mechanism is the primary cause of plastic deformation in both nanoindentation/nanoscratch. However, secondary cooperative mechanisms are varied significantly according to grain size. Pileup formation was observed in the front of and sideways of the tool, and they exhibit strong dependence on grain orientation rather than grain size. Tip size has significant impact on nanoscratch characteristics; both frictional and normal forces monotonically increase as tip radii increase, while the friction coefficient value drops by about 38%. Additionally, the increase in scratch depth leads to an increase in frictional and normal forces as well as friction coefficient. To elucidate the relevance of indentation/scratch results with mechanical properties, uniaxial tensile test was performed for nc-samples, and the result indicates the existence of both the regular and inverse Hall-Petch relations at critical grain size of 110.9 Å . The present results suggest that indentation/scratch hardness has no apparent correlation with the mechanical properties of the substrate, whereas the plastic deformation has.

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“…For nt Cu samples, surface pileup is more pronounced with a larger TBS. It is known that surface pileup results from the accumulation of surface steps formed when the motion of dislocation gliding on 1-10 {111} slip systems terminates at the surface 31 and that the pileup formation is more pronounced in materials with less work hardening. From the MD simulation we conclude that the stronger work hardening in the nt materials is caused by frequent dislocation-twin boundary interactions.…”

Section: Frictional Behavior In Nt Polycrystalline Cumentioning

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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Influence of crystal anisotropy on elastic deformation and onset of plasticity in nanoindentation: A simulational study

Abstract: Articles you may be interested inEffect of microstructure anisotropy on the deformation of MAX polycrystals studied by in-situ compression combined with neutron diffraction Appl. Phys. Lett.

Cited by 144 publications

References 29 publications

Mechanisms of anisotropic friction in nanotwinned Cu revealed by atomistic simulations

Mechanisms of anisotropic friction in nanotwinned Cu revealed by atomistic simulations

Atomistic Insights on the Wear/Friction Behavior of Nanocrystalline Ferrite During Nanoscratching as Revealed by Molecular Dynamics

Twin boundary spacing-dependent friction in nanotwinned copper

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