Retardation of Dislocation Generation and Motion in Thin-Layered Metal Laminates

Lehoczky, S. L.

doi:10.1103/physrevlett.41.1814

Cited by 142 publications

(30 citation statements)

References 7 publications

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“…Below L crit , however, another thermally activated mechanism becomes predominant, likely dislocation-interface crossing, which prevails when the stress to bow out dislocation segments within the nano-layers exceeds the threshold stress for dislocation transmission across the interface. 28,29 Our results on the ARB NMM suggest that the interface crossing mechanism is accompanied by a substantial drop in hardness with temperature. The higher L crit for ARB than PVD can be explained as an interface effect and is in agreement with indirect evidence provided by recent MD calculations suggesting that dislocation transmission across the ARB interface is easier than across the PVD interface.…”

mentioning

confidence: 85%

“…By contrast, the strength continues to increase with decreasing layer thickness for all temperatures in the PVD Cu-Nb NMM, even for the smallest layer thickness of L = 5 nm. It has been suggested 4,28 that the plateau or softening signifies the predominance of dislocation glide across interfaces over dislocation glide within individual layers. The mechanism of interface crossing is thermally activated and in principle would be enhanced by elevated temperatures.…”

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confidence: 99%

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Optimum high temperature strength of two-dimensional nanocomposites

et al. 2013

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High-temperature nanoindentation was used to reveal nano-layer size effects on the hardness of two-dimensional metallic nanocomposites. We report the existence of a critical layer thickness at which strength achieves optimal thermal stability. Transmission electron microscopy and theoretical bicrystal calculations show that this optimum arises due to a transition from thermally activated glide within the layers to dislocation transmission across the layers. We demonstrate experimentally that the atomic-scale properties of the interfaces profoundly affect this critical transition. The strong implications are that interfaces can be tuned to achieve an optimum in high temperature strength in layered nanocomposite structures.

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confidence: 85%

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confidence: 99%

Optimum high temperature strength of two-dimensional nanocomposites

et al. 2013

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“…Recent advances in coating technologies permit the deposition of multilayers with superior chemical and mechanical properties using PVD and plasma-assisted PVD [386]. Typical examples of these multilayered structures include Al/Cu, Al/Ag [445,446], TiN/AlN [447], TiN/VN [448], TiN/NbN [449,450]. The hardness of TiN/VN and TiN/NbN coatings exceeds 50 GPa when the superlattice bilayer period is around 5 nm.…”

Section: Superhard and Super-tough Nanocrystalline Coatingsmentioning

confidence: 99%

Nanocrystalline materials and coatings

Tjong

Chen

2004

Materials Science and Engineering: R: Reports

832

345

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In recent years, near-nano (submicron) and nanostructured materials have attracted increasingly more attention from the materials community. Nanocrystalline materials are characterized by a microstructural length or grain size of up to about 100 nm. Materials having grain size of $0.1 to 0.3 mm are classified as submicron materials. Nanocrystalline materials exhibit various shapes or forms, and possess unique chemical, physical or mechanical properties. When the grain size is below a critical value ($10-20 nm), more than 50 vol.% of atoms is associated with grain boundaries or interfacial boundaries. In this respect, dislocation pile-ups cannot form, and the Hall-Petch relationship for conventional coarse-grained materials is no longer valid. Therefore, grain boundaries play a major role in the deformation of nanocrystalline materials. Nanocrystalline materials exhibit creep and super plasticity at lower temperatures than conventional micro-grained counterparts. Similarly, plastic deformation of nanocrystalline coatings is considered to be associated with grain boundary sliding assisted by grain boundary diffusion or rotation. In this review paper, current developments in fabrication, microstructure, physical and mechanical properties of nanocrystalline materials and coatings will be addressed. Particular attention is paid to the properties of transition metal nitride nanocrystalline films formed by ion beam assisted deposition process. #

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“…The most common phenomenon is that the multilayers often show hardness enhancements with decreasing modulation periodicity. The potential mechanisms for explaining it include modulus mismatch hardening, coherency stress hardening, structure barrier strengthening and supermodulus effect [1][2][3][4][5][6][7]. However, few results about the mechanical properties of c-/a-and a-/ametal multilayers are reported [8][9][10], and how the modulation periodicity affects the mechanical properties of a-/a-metal multilayers requires further understanding.…”

Section: Introductionmentioning

confidence: 91%

“…The mechanical properties of crystalline/crystalline (c-/c-) metallic multilayers are intensively studied [1][2][3][4][5][6][7]. The most common phenomenon is that the multilayers often show hardness enhancements with decreasing modulation periodicity.…”

Section: Introductionmentioning

confidence: 99%