Nanoindentation response of nanocrystalline copper via molecular dynamics: Grain-size effect

Li, Jiejie; Lu, Binbin; Zhang, Yuhang; Zhou, Hongjian; Hu, Guoming; Xia, Re

doi:10.1016/j.matchemphys.2019.122391

Cited by 50 publications

(24 citation statements)

References 61 publications

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“…Increasing the grain size leads to a reduction in the grain boundaries ratio and a rise in the ratio of the crystalline atoms, resulting in a higher level of elastic recovery. This result is similar to the reverse Hall–Petch effect that appeared in nanocrystalline materials that the grain size is smaller than 10 nm 24 , 25 . In this range, the smaller nanocrystalline diamond grain tends to be easier destroyed comparing to the larger one.…”

Section: Resultssupporting

confidence: 85%

“…The larger grain size mostly has the shallower groove depth. In other words, the larger grain size demonstrates a higher elastic capacity because it has a higher grain-boundary ratio, a good result compared to other studies 10 , 24 . Because the atoms in the grain boundaries exist in a disordered structure, having a lower density than the atoms inside the grain.…”

Section: Resultssupporting

confidence: 61%

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Phase transformation and subsurface damage formation in the ultrafine machining process of a diamond substrate through atomistic simulation

Nguyen

Fang

2021

Sci Rep

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This report explores the effects of machining depth, velocity, temperature, multi-machining, and grain size on the tribological properties of a diamond substrate. The results show that the appearance of graphite atoms can assist the machining process as it reduces the force. Moreover, the number of graphite atoms relies on the machining speed and substrate temperature improvement caused by the friction force. Besides, machining in a machined surface for multi-time is affected by its rough, amorphous, and deformed surface. Therefore, machining in the vertical direction for multi-time leads to a higher rate of deformation but a reduction in the rate of graphite atoms generation. Increasing the grain size could produce a larger graphite cluster, a higher elastic recovery rate, and a higher temperature but a lower force and pile-up height. Because the existence of the grain boundaries hinders the force transformation process, and the reduction in the grain size can soften the diamond substrate material.

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Section: Resultssupporting

confidence: 85%

Section: Resultssupporting

confidence: 61%

Phase transformation and subsurface damage formation in the ultrafine machining process of a diamond substrate through atomistic simulation

Nguyen

Fang

2021

Sci Rep

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“…It can be found that the nano-hardness of the bulging region (regions 2–6) is generally higher than that of the unformed region (regions 1 and 7), which is similar to the results obtained by Cheng et al [ 39 ]. This is because with the increase of plastic strain, the movement of crystal dislocations becomes dense, resulting in the increase of hardness [ 40 ]. It is worth noting that the elastic modulus changes little in the unformed region and the mold entrance zone, but decreases significantly in the bulging zone.…”

Section: Resultsmentioning

confidence: 99%

Mold Size Effect in Microscale Laser Dynamic Flexible Bulging Assisted by Laser Pre-Shocking

et al. 2022

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The size effect seriously affects the forming quality of micro-formed parts in the field of micro-forming. This paper focuses on the influence of the mold size effect in microscale laser dynamic flexible bulging (μLDFB). The experimental results indicate that, for the copper foil with a given thickness, there are suitable mold characteristic sizes to obtain better forming quality. The surface quality of bulging parts is poor when the mold characteristic size is small. However, the forming symmetry and forming uniformity of bulging samples are reduced when the mold characteristic size is large. As the laser pulse energy increases, the plastic strain increases, and the bulging samples experience five stages: uniform plastic deformation, local necking, cracks in the bulging zone, complete fracture in the bulging zone and complete rupture at the mold entrance zone. The increase of the surface roughening rate caused by the increase of grain size and mold characteristic size makes local necking easier, which further leads to fracture. On this basis, in this paper laser pre-shocking (LPS) is introduced to improve the forming quality. Comparative experiments show that LPS has a positive effect on improving the surface quality and the forming performance of bulging samples. The forming limit of bulging samples is increased and the occurrence of local necking is delayed.

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“…MD simulation directly depicts the interaction of atoms. In recent decades, it has been widely employed to investigate the mechanical properties of single crystals and nanopolycrystalline materials (e.g., nano-polycrystal silicon [25] and copper [26]) by means of nanoindentation or many other tests [11]. However, MD simulation is only suitable for nanoscale specimens due to the extremely heavy computational load.…”

Section: Introductionmentioning

confidence: 99%

Development of the Concurrent Multiscale Discrete-Continuum Model and Its Application in Plasticity Size Effect

2022

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A concurrent multiscale model coupling discrete dislocation dynamics to the finite element method is developed to investigate the plastic mechanism of materials at micron/submicron length scales. In this model, the plastic strain is computed in discrete dislocation dynamics (DDD) and transferred to the finite element method (FEM) to participate in the constitutive law calculation, while the FEM solves the complex boundary problem for DDD simulation. The implementation of the whole coupling scheme takes advantage of user subroutines in the software ABAQUS. The data structures used for information transferring are introduced in detail. Moreover, a FE mesh-based regularization method is proposed to localize the discrete plastic strain to continuum material points. Uniaxial compression tests of single crystal micropillars are performed to validate the developed model. The results indicate the apparent dependence of yield stress on sample size, and its underlying mechanisms are also analyzed.

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Nanoindentation response of nanocrystalline copper via molecular dynamics: Grain-size effect

Cited by 50 publications

References 61 publications

Phase transformation and subsurface damage formation in the ultrafine machining process of a diamond substrate through atomistic simulation

Phase transformation and subsurface damage formation in the ultrafine machining process of a diamond substrate through atomistic simulation

Mold Size Effect in Microscale Laser Dynamic Flexible Bulging Assisted by Laser Pre-Shocking

Development of the Concurrent Multiscale Discrete-Continuum Model and Its Application in Plasticity Size Effect

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