Pseudoelastic Deformation during Nanoscale Adhesive Contact Formation

Mordehai, Dan; Rabkin, Eugen; Srolovitz, David J.

doi:10.1103/physrevlett.107.096101

Cited by 28 publications

(19 citation statements)

References 31 publications

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“…Here, one can assume that homogeneous dislocation nucleation is not favoured (when compared to SDN) due to the competition between subsurface shear stress concentration on one hand, and nanoscale properties such as surface atomic discretization, orientation of surface ledge, and dislocation line energy on the other hand. Nevertheless, while this process recently drew particular attention [11,47,49], it might not be realistic. Indeed, the pyramidal dislocation structure, which, up to now, has only been observed in MD simulations, results from the interaction of four Shockley partial dislocations simultaneously nucleated in four 1 6 112 {111} slip systems of maximum Schmid factor.…”

Section: Elementary Deformation Processesmentioning

confidence: 99%

Influence of an amorphous surface layer on the mechanical properties of metallic nanoparticles under compression

Goryaeva

Fusco

Bugnet

et al. 2019

Phys. Rev. Materials

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This study aims to investigate the role of amorphous surface layers on the mechanical response of metallic nanoparticles under compression using molecular dynamics simulations. For this purpose, the transferability of three embedded-atom-method (EAM) potentials to model monoatomic Ni glass and amorphous-crystalline structures is examined. Particular attention is paid to the crystallisation rate of the amorphous shell surrounding the crystalline inner structure. Relying on the most appropriate model, the influence of the amorphous layer on the mechanical response of crystalline-amorphous Ni nanoparticles is further investigated. Regardless of its thickness, the amorphous surface layer significantly changes both the effective elastic modulus of the nanoparticle and the flow stress. Besides stress, dislocation nucleation processes as well as the final shape of the compressed particles are influenced by the presence of the amorphous shell. These results bring new insights on the influence of surface state on the mechanics of metallic nano-objects.

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Section: Elementary Deformation Processesmentioning

confidence: 99%

Influence of an amorphous surface layer on the mechanical properties of metallic nanoparticles under compression

Goryaeva

Fusco

Bugnet

et al. 2019

Phys. Rev. Materials

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“…5a), which indicates the occurrence of plastic deformation during the cold welding process. Generally, when two nanostructures come into contact, a large mechanical stress could be induced at the contact zone owing to the mismatch of geometry and orientation, which can result in the so-called dislocation-mediated pseudoelastic deformation if the contact surface is atomically flat 39 . In our experiment, however, the surfaces of the two nanostructures are not atomically flat (Fig.…”

Section: Formation Of Dislocation-originated Sft By Dislocationmentioning

confidence: 99%

Atomic-scale dynamic process of deformation-induced stacking fault tetrahedra in gold nanocrystals

et al. 2013

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Stacking fault tetrahedra, the three-dimensional crystalline defects bounded by stacking faults and stair-rod dislocations, are often observed in quenched or irradiated face-centred cubic metals and alloys. All of the stacking fault tetrahedra experimentally observed to date are believed to originate from vacancies. Here we report, in contrast to the classical vacancyoriginated ones, a new kind of stacking fault tetrahedra formed via the interaction and crossslip of partial dislocations in gold nanocrystals. The complete atomic-scale processes of nucleation, migration and annihilation of the dislocation-originated stacking fault tetrahedra are revealed by in situ high-resolution observations and molecular dynamics simulations. The dislocation-originated stacking fault tetrahedra can undergo migration and annihilation due to mechanical loading in a manner that is not expected in bulk samples. These results uncover a unique deformation mechanism via dislocation interaction inside the confined volume of nanocrystals and have important implications regarding the size effect on the mechanical behaviour of small-volume materials.

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“…Crystalline defects that were initially present in the nanocrystals after deformation may have healed before imaging through dislocation-mediated processes such as escape through free surfaces. [3,4] Our discovery of pseudoelasticity in small Au nanocrystals implies that the metallic nanostructures used in nanoscale machines, devices and patterned surfaces may demonstrate rapid self-healing and resilience against external stresses and strains. The relevance of these findings extends beyond nanofabrication and crystal growth.…”

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confidence: 99%

Pseudoelasticity at Large Strains in Au Nanocrystals

Hanson

Eisler

et al. 2018

Phys. Rev. Lett.

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Pseudoelasticity in metals is typically associated with phase transformations (e.g., shape memory alloys) but has recently been observed in sub-10 nm Ag nanocrystals that rapidly recovered their original shape after deformation to large strains. The discovery of pseudoelasticity in nanoscale metals dramatically changes the current understanding of the properties of solids at the smallest length scales, and the motion of atoms at surfaces. Yet, it remains unclear whether pseudoelasticity exists in different metals and nanocrystal sizes. The challenge of observing deformation at atomistic to nanometer length scales has prevented a clear mechanistic understanding of nanoscale pseudoelasticity, although surface diffusion and dislocation-mediated processes have been proposed. We further the understanding of pseudoelasticity in nanoscale metals by using a diamond anvil cell to compress colloidal Au nanocrystals under quasihydrostatic and nonhydrostatic pressure conditions. Nanocrystal structural changes are measured using optical spectroscopy and transmission electron microscopy and modeled using electrodynamic theory. We find that 3.9 nm Au nanocrystals exhibit pseudoelastic shape recovery after deformation to large uniaxial strains of up to 20%, which is equivalent to an ellipsoid with an aspect ratio of 2. Nanocrystal absorbance efficiency does not recover after deformation, which indicates that crystalline defects may be trapped in the nanocrystals after deformation.

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Pseudoelastic Deformation during Nanoscale Adhesive Contact Formation

Cited by 28 publications

References 31 publications

Influence of an amorphous surface layer on the mechanical properties of metallic nanoparticles under compression

Influence of an amorphous surface layer on the mechanical properties of metallic nanoparticles under compression

Atomic-scale dynamic process of deformation-induced stacking fault tetrahedra in gold nanocrystals

Pseudoelasticity at Large Strains in Au Nanocrystals

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