Molecular-dynamics study of mechanical deformation in nano-crystalline aluminum

Kadau, Kai; Lomdahl, Peter S.; Holian, Brad Lee; Germann, Timothy C.; Kadau, Dirk; Entel, P.; Wolf, Dietrich E.; Kreth, M.; Westerhoff, F.

doi:10.1007/s11661-004-0217-2

Cited by 69 publications

(38 citation statements)

References 21 publications

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“…Recent molecular dynamics (MD) simulations have improved our understanding of the deformation of nanocrystalline materials [13]. The MD simulations in nanocrystalline copper [20][21][22][23], aluminum [11,24], nickel [22,23] and cobalt [25], where an inverse Hall-Petch effect was observed [11,17,20,21,[24][25][26], revealed the difference between the grain interior and the grain boundary regions where most of the deformation occurred due to the inter-grain deformation (sliding) mechanism [20,22,23,27,28]. It was further observed that the volume fraction of the total grain boundaries, which increases with decreasing grain size [29], increases under straining conditions, indicating an expansion of the grain boundary regions during straining [11].…”

Section: Introductionmentioning

confidence: 99%

Modeling the dependence of strength on grain sizes in nanocrystalline materials

Bhole

Chen

2008

Science and Technology of Advanced Materials

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A model was developed to describe the grain size dependence of hardness (or strength) in nanocrystalline materials by combining the Hall-Petch relationship for larger grains with a coherent polycrystal model for nanoscale grains and introducing a log-normal distribution of grain sizes. The transition from the Hall-Petch relationship to the coherent polycrystal mechanism was shown to be a gradual process. The hardness in the nanoscale regime was observed to increase with decreasing grain boundary affected zone (or effective grain boundary thickness, ) in the form of −1/2 . The critical grain size increased linearly with increasing . The variation of the calculated hardness value with the grain size was observed to be in agreement with the experimental data reported in the literature.

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Section: Introductionmentioning

confidence: 99%

Modeling the dependence of strength on grain sizes in nanocrystalline materials

Bhole

Chen

2008

Science and Technology of Advanced Materials

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“…Lots of MD simulations have been carried out to investigate the strain rate effect of nanoscale structures [11][12][13][14]. These simulations demonstrate some results similar to that observed in experiments.…”

Section: Introductionmentioning

confidence: 56%

“…However the simulated sample sizes are restricted to tens of nm, much smaller than that in laboratory tests. Moreover, the strain rates involved in previous MD simulations are quite high (usually higher than 10 8 s −1 [11,13] in contrast to those appearing in most laboratory tests, like 10 −3 s −1 . The limitations of MD simulation should be attributed to its intrinsic length and time scales involved in the potential functions used to characterize the inter-molecular interactions [15].…”

Section: Introductionmentioning

confidence: 91%

Rate effect and coupled evolution of atomic motions and potential landscapes

et al. 2013

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Since rate effect of materials plays a key role in impact engineering, the microscopic mechanism of rate effect is investigated at molecular level in this paper. The results show that rate effect on the strength of atomic system is closely related to the coupled evolution of atomic motions and potential landscapes. Accordingly, it becomes possible to develop a new algorithm of molecular simulation, which could properly and efficiently demonstrate strain rate effect under a wide range of loading rates and unveil the mechanisms underlying the strain rate effects.

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“…Because of a shift in the dominant deformation mechanisms from dislocationmediated plasticity to GB-associated plasticity, the strength/hardness of metals has been found to increase first with decreasing grain size down to a critical grain size (10-20 nm), and then decrease with further grain refinement [1,2,[9][10][11][12][13][14][15]. Moreover, a similar trend for twinboundary spacing (TBS) effect on the strength of nanotwinned (NT) metals was also found due to a transition of deformation mechanisms [16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 91%

Smaller critical size and enhanced strength by nano-laminated structure in nickel

Wang

Yuan

2015

Computational Materials Science

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a b s t r a c tBecause of a shift in the dominant deformation mechanisms, the strength/hardness of metals increases with decreasing grain size down to a critical value, then decreases with further grain refinement. Here, laminated structure with low-angle grain boundaries was found to have smaller critical size and enhanced strength when compared to the equiaxed grain structure, through a series of large-scale molecular dynamics simulations. Then, the corresponding atomistic mechanisms were investigated by checking and comparing the rotations of grains and equivalent strain partitioning in grain boundary atoms. In laminated structure, grain boundary activies were found to be promoted with decreasing lamellar thickness. More importantly, when compared to the equiaxed grain structure at the same length scale (lamellar thickness/grain size), grain boundary activities were found to be inhibited by the laminated structure, which is the main reason for the enhanced strength and the smaller critical size. Besides grain boundary activities, formation of extended dislocations, formation of deformation twins, partial dislocations interacting with formed TBs, partial dislocation blocking by and even transmission through low-angle grain boundaries were also found to play important roles in plastic deformation of nano-laminated structure. The current findings should provide insights for designing stronger and more stable nanostructured metals.Ó 2015 Published by Elsevier B.V.

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Molecular-dynamics study of mechanical deformation in nano-crystalline aluminum

Cited by 69 publications

References 21 publications

Modeling the dependence of strength on grain sizes in nanocrystalline materials

Modeling the dependence of strength on grain sizes in nanocrystalline materials

Rate effect and coupled evolution of atomic motions and potential landscapes

Smaller critical size and enhanced strength by nano-laminated structure in nickel

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