The effect of crystal anisotropy and pre-existing defects on the incipient plasticity of FCC single crystals during nanoindentation

Bagheripoor, Mahdi; Klassen, Robert D.

doi:10.1016/j.mechmat.2020.103311

Cited by 30 publications

(7 citation statements)

References 41 publications

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“…There are also some relevant studies for the defect and mechanical anisotropy in other materials like borophene, gold, graphene and black phosphorus [ 25 , 26 , 27 ]. However, for the mechanical anisotropy of monocrystalline silicon in the molecular dynamics view, the nanoscale effects of a point defect have not been reported yet.…”

Section: Introductionmentioning

confidence: 99%

General Molecular Dynamics Approach to Understand the Mechanical Anisotropy of Monocrystalline Silicon under the Nanoscale Effects of Point Defect

et al. 2021

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Mechanical anisotropy and point defects would greatly affect the product quality while producing silicon wafers via diamond-wire cutting. For three major orientations concerned in wafer production, their mechanical performances under the nanoscale effects of a point defect were systematically investigated through molecular dynamics methods. The results indicated anisotropic mechanical performance with fracture phenomena in the uniaxial deformation process of monocrystalline silicon. Exponential reduction caused by the point defect has been demonstrated for some properties like yield strength and elastic strain energy release. Dislocation analysis suggested that the slip of dislocations appeared and created hexagonal diamond structures with stacking faults in the [100] orientation. Meanwhile, no dislocation was observed in [110] and [111] orientations. Visualization of atomic stress proved that the extreme stress regions of the simulation models exhibited different geometric and numerical characteristics due to the mechanical anisotropy. Moreover, the regional evolution of stress concentration and crystal fracture were interrelated and mutually promoted. This article contributes to the research towards the mechanical and fracture anisotropy of monocrystalline silicon.

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Section: Introductionmentioning

confidence: 99%

General Molecular Dynamics Approach to Understand the Mechanical Anisotropy of Monocrystalline Silicon under the Nanoscale Effects of Point Defect

et al. 2021

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“…It was also observed that as the deformation volume of a material decreases, the effect of crystal orientation on the operative deformation mechanisms increases; in particular, the mechanical response of sub-micron defect-free nanopillars is different depending on whether they are deformed along high symmetry orientations or low symmetry orientations [35,36]. The compression tests on confined micropillars revealed higher (and therefore closer to theoretical limit) stresses of massive dislocation nucleation than in the presence of free surfaces [36,37].…”

Section: Introductionmentioning

confidence: 82%

Discontinuous yielding of pristine micro-crystals

Salman¹,

Baggio²,

Bacroix³

et al. 2021

Comptes Rendus. Physique

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We study the mechanical response of a dislocation-free 2D crystal under homogenous shear using a new mesoscopic approach to crystal plasticity, a Landau-type theory, accounting for the global invariance of the energy in the space of strain tensors while operating with an infinite number of equivalent energy wells. The advantage of this approach is that it eliminates arbitrariness in dealing with topological transitions involved, for instance, in nucleation and annihilation of dislocations. We use discontinuous yielding of pristine micro-crystals as a benchmark problem for the new theory and show that the nature of the catastrophic instability, which in this setting inevitably follows the standard affine response, depends not only on lattice symmetry but also on the orientation of the crystal in the loading device. The ensuing dislocation avalanche involves cooperative dislocation nucleation, resulting in the formation of complex microstructures controlled by a nontrivial self-induced coupling between different plastic mechanisms.

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“…Pre-existing lattice defects, including dislocations and dislocation sources, affect the behavior of plasticity initiation beneath an indenter [ 32 , 112 , 113 , 114 , 115 , 116 , 117 , 118 , 119 , 120 , 121 , 122 , 123 , 124 ]. Bahr et al demonstrated that the critical stress for yielding can reach the theoretical strength of W and Fe only under a low density of dislocation source [ 112 ].…”

Section: Effect Of Pre-existing Lattice Defectsmentioning

confidence: 99%

Pop-In Phenomenon as a Fundamental Plasticity Probed by Nanoindentation Technique

Ohmura

Wakeda

2021

Materials

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The attractive strain burst phenomenon, so-called “pop-in”, during indentation-induced deformation at a very small scale is discussed as a fundamental deformation behavior in various materials. The nanoindentation technique can probe a mechanical response to a very low applied load, and the behavior can be mechanically and physically analyzed. The pop-in phenomenon can be understood as incipient plasticity under an indentation load, and dislocation nucleation at a small volume is a major mechanism for the event. Experimental and computational studies of the pop-in phenomenon are reviewed in terms of pioneering discovery, experimental clarification, physical modeling in the thermally activated process, crystal plasticity, effects of pre-existing lattice defects including dislocations, in-solution alloying elements, and grain boundaries, as well as atomistic modeling in computational simulation. The related non-dislocation behaviors are also discussed in a shear transformation zone in bulk metallic glass materials and phase transformation in semiconductors and metals. A future perspective from both engineering and scientific views is finally provided for further interpretation of the mechanical behaviors of materials.

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The effect of crystal anisotropy and pre-existing defects on the incipient plasticity of FCC single crystals during nanoindentation

Cited by 30 publications

References 41 publications

General Molecular Dynamics Approach to Understand the Mechanical Anisotropy of Monocrystalline Silicon under the Nanoscale Effects of Point Defect

General Molecular Dynamics Approach to Understand the Mechanical Anisotropy of Monocrystalline Silicon under the Nanoscale Effects of Point Defect

Discontinuous yielding of pristine micro-crystals

Pop-In Phenomenon as a Fundamental Plasticity Probed by Nanoindentation Technique

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