Atomistic studies of nanohardness size effects

Chan, Chia‐Hsin; Chen, Yen Yu; Chang, Shyang; Chen, Chuin Shan

doi:10.1504/ijtamm.2011.041174

Cited by 5 publications

(4 citation statements)

References 16 publications

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“…Many studies have adopted atomistic simulations to probe and understand detailed deformation process and the possible impact factors involved in nanoindentation. For example, Chan et al [10] studied the size effects of indenter nanohardness using atomistic simulations, and found that nanohardness was inversely proportional to the indenter radius. Imran et al [11] studied the influence from the indenter velocity and size of the indenter using molecular dynamics (MD) simulations in Ni single crystals.…”

Section: Introductionmentioning

confidence: 99%

Indenter Shape Dependent Dislocation Actives and Stress Distributions of Single Crystal Nickel during Nanoindentation: A Molecular Dynamics Simulation

Wu¹,

Li²,

Zhang³

2020

Advances in Condensed-Matter and Materials Physics - Rudimentary Research to Topical Technology

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The influences of indenter shape on dislocation actives and stress distributions during nanoindentation were studied by using molecular dynamics (MD) simulation. The load-displacement curves, indentation-induced stress fields, and dislocation activities were analyzed by using rectangular, spherical, and Berkovich indenters on single crystal nickel. For the rectangular and spherical indenters, the load-displacement curves have a linear dependence, but the elastic stage produced by the spherical indenter does not last longer than that produced by the rectangular indenter. For a Berkovich indenter, there is almost no linear elastic regime, and an amorphous region appears directly below the indenter tip, which is related to the extremely singular stress field around the indenter tip. In three indenters cases, the prismatic dislocation loops are observed on the {111} planes, and there is a sudden increase in stress near the indenter for the Berkovich indenter. The stress distributions are smooth with no sudden irregularities at low-indentation depths; and the stress increases and a sudden irregularity appears with the increasing indentation depths for the rectangular and spherical indenters. Moreover, the rectangular indenter has the most complex dislocation activities and the spherical indenter is next, while very few dislocations occur in the Berkovich indenter case.

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Section: Introductionmentioning

confidence: 99%

Indenter Shape Dependent Dislocation Actives and Stress Distributions of Single Crystal Nickel during Nanoindentation: A Molecular Dynamics Simulation

Wu¹,

Li²,

Zhang³

2020

Advances in Condensed-Matter and Materials Physics - Rudimentary Research to Topical Technology

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“…Atomistic modeling has been used to address a wide variety of deformation processes in solids recently (Chen et al 2008, Chan et al 2011, Lai and Chen 2013, Chen and Lee 2010, Jeong et al 2011, Shen 2013, Teng et al 2011, Wang et al 2013, Zhao and Aluru 2008. The advantage of fully atomistic modeling is its capability to provide desirable resolution that accounts for highly inhomogeneous deformations caused by lattice defects in materials.…”

Section: Introductionmentioning

confidence: 99%

Energy and force transition between atoms and continuum in quasicontinuum method

Chang¹,

Liao²,

Huang³

et al. 2014

Interaction and multiscale mechanics

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We present a full energy and force formulation of the quasicontinuum method with non-local and local transition elements. Non-local transition elements are developed to transmit inhomogeneity from the atomistic to the continuum regions. Local transition elements are developed to resolve the mathematical mismatch between non-local atoms and the local continuum. The rationale behind these transition elements is provided by analyzing the energy and force transitions between atoms and continuum under the Cauchy-Born rule. We show that breakdown of the Cauchy-Born rule occurs for slaved atoms of local elements within the cutoff of non-local atoms. The inadequacy of the Cauchy-Born rule at the transition region naturally leads to the need of atomistic treatment of transition slaved and transition representative atoms. Such an atomistic treatment together with a full or cutoff sampling allows non-local transition elements containing these transition entities to transmit inhomogeneity. Different force formulations for transition representative atoms and pure local representative atoms allow the local transition elements to resolve non-local and local mismatches. The method presented herein is validated by force calculations in an unstressed perfect crystal as well as an unrelaxed grain boundary model. A nanoindentation simulation in 3D is conducted to demonstrate the accuracy and efficiency of the proposed method.

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“…With recent advances in computing power, researchers have adopted atomistic simulations to probe and understand detailed deformation processes and the mechanisms involved in nanoindentation (Lilleodden et al 2003, Lee et al 2005, Chen et al 2008, Chan et al 2011. Lilleodden et al (2003) carried out an atomistic study of Au nanoindentation and reported the Corresponding author, Professor, E-mail: dchen@ntu.edu.tw elastic anisotropy of Au metal.…”

Section: Introductionmentioning

confidence: 99%

“…For both samples, the mean contact pressure varied significantly during the early stages of indentation but reached a steady value soon after the first apparent load drop. Chan et al (2011) studied the size effects of nanoindentation using atomistic simulations. For spherical indenters with radii ranging from 10 to 50 Å , it was found that nanohardness was inversely proportional to the indenter radius.…”

Section: Introductionmentioning

confidence: 99%

Influence of indenter shape on nanoindentation: an atomistic study

Lai¹,

Chen

2013

Interaction and multiscale mechanics

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The influence of indenter geometry on nanoindentation was studied using a static molecular dynamics simulation. Dislocation nucleation, dislocation locks, and dislocation movements during nanoindentation into Al (001) were studied. Spherical, rectangular, and Berkovich indenters were modeled to study the material behaviors and dislocation activities induced by their different shapes. We found that the elastic responses for the three cases agreed well with those predicted from elastic contact theory. Complicated stress fields were generated by the rectangular and Berkovich indenters, leading to a few uncommon nucleation and dislocation processes. The calculated mean critical resolved shear stresses for the Berkovich and rectangular indenters were lower than the theoretical strength. In the Berkovich indenter case, an amorphous region was observed directly below the indenter tip. In the rectangular indenter case, we observed that some dislocation loops nucleated on the plane. Furthermore, a prismatic loop originating from inside the material glided upward to create a mesa on the indenting surface. We observed an unusual softening phenomenon in the rectangular indenter case and proposed that heterogeneously nucleating dislocations are responsible for this.

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Atomistic studies of nanohardness size effects

Cited by 5 publications

References 16 publications

Indenter Shape Dependent Dislocation Actives and Stress Distributions of Single Crystal Nickel during Nanoindentation: A Molecular Dynamics Simulation

Indenter Shape Dependent Dislocation Actives and Stress Distributions of Single Crystal Nickel during Nanoindentation: A Molecular Dynamics Simulation

Energy and force transition between atoms and continuum in quasicontinuum method

Influence of indenter shape on nanoindentation: an atomistic study

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