Atomistic simulations of elastic deformation and dislocation nucleation during nanoindentation

Lilleodden, Erica T.; Zimmerman, Jonathan A.; Foiles, Stephen M.; Nix, William D.

doi:10.1016/s0022-5096(02)00119-9

Cited by 263 publications

(172 citation statements)

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“…It is well documented that induced by nanoindentation the nanoscale deformation of bulk Si is accompanied with the phase transformation from the initial diamond- cubic (Si(I)) to the high-pressure β-tin (Si(II)) phase [5][6][7][8]15]. In contrast to the case of GaAs, loading of the indenter does not produce the pop-in associated with the mentioned phase change.…”

Section: Resultsmentioning

confidence: 99%

“…Silicon, one of the most extensively studied advanced technology materials exhibits a complex pattern of plastic deformation combining amorphization [5,6], phase transformations [5][6][7][8], and dislocations [7,8]. Recent nanoscale compression [9,10] and nanoindentation observations [7] demonstrated that deformation of silicon nanovolumes is markedly different from behavior of the * corresponding author; e-mail: dariusz.chrobak@us.edu.pl bulk material.…”

Section: Introductionmentioning

confidence: 99%

“…Recent nanoscale compression [9,10] and nanoindentation observations [7] demonstrated that deformation of silicon nanovolumes is markedly different from behavior of the * corresponding author; e-mail: dariusz.chrobak@us.edu.pl bulk material. The enhanced hardness of Si nanospheres is consistent with the known phenomenon of yield stress increase due to the decrease of dimensions of deformed volumes [9,10].…”

Section: Introductionmentioning

confidence: 99%

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Influence of Phase Transformations on Incipient Plasticity of Si-Nanospheres

Chrobak

Nowak

2017

Acta Phys. Pol. A

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Our finding of the current spike effect highlighted for the first time in 2009 offers an enhanced understanding of the link between nanoscale mechanical deformation and electrical behavior, and ultimately suggests key advances in unique phase-change applications in future electronics. Certainly, crystal imperfections affect the properties of the nanoparticles themselves, e.g., their biocompatibility and biodegradability. The potential role of dislocations having a profound impact on the use of Si nanoparticles was largely overlooked, since plastic deformation of bulk Si is dominated by amorphization and phase transformations. Here we show an effect of bulk → nanoparticle transition (deconfinement) on incipient plasticity of Si-nanovolume. Our results provide a fresh insight into the dilemma concerning dislocation or phase transformation origin of nanoscale plastic deformation of semiconductor nanoobjects.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Phase Transformations on Incipient Plasticity of Si-Nanospheres

Chrobak

Nowak

2017

Acta Phys. Pol. A

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“…There are a number of MD simulations that capture the evolution of dislocation microstructure to various degrees [21,[23][24][25][26]. Features that emerge from these simulations include the nucleation of dislocation loops, their expansion and interaction, detachment from the source, and their propagation [26].…”

Section: Insights From Simulations On Nanoindentationmentioning

confidence: 99%

“…The latter, in particular, has been useful in visualizing the dislocation nucleation mechanism in real materials [20]. Finally, considerable theoretical understanding has come from various types of simulation studies such as molecular dynamics (MD) simulations [21][22][23][24][25][26], dislocation dynamics simulations and multiscale modeling simulations (using MD together with dislocation dynamics simulations) [26]. While there are a number of MD simulations for the DC mode, there are no simulations of any kind that predict displacement jumps reported in the LC mode experiments.…”

Section: Introductionmentioning

confidence: 99%

A Novel Approach to Modelling Nanoindentation Instabilities

Ananthakrishna

Krishnamoorthy

2018

Crystals

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Abstract:We review the recently developed models for load fluctuations in the displacement controlled mode and displacement jumps in the load controlled mode of indentation. To do this, we devise a method for calculating plastic contribution to load drops and displacement jumps by setting-up a system of coupled nonlinear time evolution equations for the mobile and forest dislocation densities by including relevant dislocation mechanisms. These equations are then coupled to the equation defining constant displacement rate or load rate. The model for the displacement controlled mode using a spherical indenter predicts all the generic features of nanoindentation such as the elastic branch followed by several force drops of decreasing magnitudes and residual indentation depth after unloading. The stress corresponding to the elastic force maximum is close to the yield stress of an ideal solid. The predicted numbers for all the quantities match experiments on single crystals of Au using a spherical indenter. We extend the approach to model the load controlled nanoindentation experiments that employ a Berkovich indenter. We first identify the dislocation mechanisms contributing to different regions of the F − z curve as a first step for obtaining a good fit to a given experimental F − z curve. This is done by studying the influence of the parameters associated with various dislocation mechanisms on the model F − z curves. The study also demonstrates that the model predicts all the generic features of nanoindentation such as the existence of an initial elastic branch followed by several displacement jumps of decreasing magnitudes and residual plasticity after unloading for a range of model parameter values. Furthermore, an optimized set of parameter values can be easily determined that give a good fit to the experimental load-displacement curves for Al single crystals of (110) and (133) orientations. Our model also predicts the indentation size effect in a region where the displacement jumps disappear. The good agreement of the results of the models with experiments supports our view that the present approach can be used as an alternate method to simulations. The approach also provides insights into several open questions.

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