Texture of Nanocrystalline Nickel: Probing the Lower Size Limit of Dislocation Activity

Chen, Bin; Lutker, Katie; Raju, Selva Vennila; Yan, Jinyuan; Kanitpanyacharoen, Waruntorn; Lei, Jialin; Yang, Shizhong; Wenk, Hans‐Rudolf; Mao, Ho‐kwang; Williams, Quentin

doi:10.1126/science.1228211

Cited by 102 publications

(86 citation statements)

References 32 publications

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“…As shown in Fig. 2, the large curvatures of the 2D diffraction lines of nickel nanocrystals also provide strong evidence for the shear stress in ultrafine nickel nanocrystals (24,27). Therefore, it is excluded that the observed texture loss of platinum in ultrafine nickel media arises from the lack of shear stress.…”

Section: Significancementioning

confidence: 86%

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Detecting grain rotation at the nanoscale

Chen

Lutker

Lei

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Significance The plastic deformation of nanomaterials has long been wrapped in mystery. Grain rotation is suggested to be a dominant mechanism of plastic deformation for ultrafine nanomaterials. However, the in situ observation of grain rotation has been made possible only for coarse-grained materials. Here we report the in situ high-pressure detection of grain rotation at the nanoscale. The surprising observation is that the texture strength of the same-sized platinum drops rapidly with decreasing grain size of the nickel medium, indicating that more active grain rotation occurs in the smaller nickel nanocrystals. Insight into these processes provides a better understanding of the plastic deformation of nanomaterials at a few-nanometer length scale.

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Section: Significancementioning

confidence: 86%

“…Such in situ high-pressure textural studies thus provide the means to investigate deformation mechanisms and help constrain the fundamental physics of deformation at the nanoscale. For the calculations, b p = 0.244 nm (9), G = 76 GPa (27,29), ν= 0.31 (27).…”

Section: Significancementioning

confidence: 99%

Detecting grain rotation at the nanoscale

Chen

Lutker

Lei

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…The combination of this two recent approaches open-up new possibilities for the use of up converting particles in many different applications: in imaging for biology of course but also for photodynamic therapy [129,130,131,132] or for photovoltaics [133].…”

Section: Up Conversion Of Photoluminescencementioning

confidence: 99%

Engineered inorganic core/shell nanoparticles

et al. 2014

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It has been for a long time recognized that nanoparticles are of great scientific interest as they are effectively a bridge between bulk materials and atomic structures. At first, size effects occurring in single elements have been studied. More recently, progress in chemical and physical synthesis routes permitted the preparation of more complex structures. Such structures take advantages of new adjustable parameters including stoichiometry, chemical ordering, shape and segregation opening new fields with tailored materials for biology, mechanics, optics magnetism, chemistry catalysis, solar cells and microelectronics. Among them, core/shell structures are a particular class of nanoparticles made with an inorganic core and one or several inorganic shell layer(s). In earlier work, the shell was merely used as a protective coating for the core. More recently, it has been shown that it is possible to tune the physical properties in a larger range than that of each material taken separately. The goal of the present review is to discuss the basic properties of the different types of core/shell nanoparticles including a large variety of heterostructures. We restrict ourselves on all inorganic (on inorganic/inorganic) core/shell structures. In the light of recent developments, the applications of inorganic core/shell particles are found in many fields including biology, chemistry, physics and engineering. In addition to a representative overview 2 of the properties, general concepts based on solid state physics are considered for material selection and for identifying criteria linking the core/shell structure and its resulting properties. Chemical and physical routes for the synthesis and specific methods for the study of core/shell nanoparticle are briefly discussed.

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“…In nanocrystalline metals, the grain boundarymediated process becomes dominant (24,25) but the size limit of the dislocation activation is extended to smaller grains at highpressure conditions (26). However, for the conventional materials with coarse grain sizes it is found that all dislocation-mediated deformation modes are activated irrespective of the grain size and the grain orientation plays an important role in the deformation modes (21-23, 27, 28).…”

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confidence: 99%

Theory for plasticity of face-centered cubic metals

Koo

Lee

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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The activation of plastic deformation mechanisms determines the mechanical behavior of crystalline materials. However, the complexity of plastic deformation and the lack of a unified theory of plasticity have seriously limited the exploration of the full capacity of metals. Current efforts to design high-strength structural materials in terms of stacking fault energy have not significantly reduced the laborious trial and error works on basic deformation properties. To remedy this situation, here we put forward a comprehensive and transparent theory for plastic deformation of face-centered cubic metals. This is based on a microscopic analysis that, without ambiguity, reveals the various deformation phenomena and elucidates the physical fundaments of the currently used phenomenological correlations. We identify an easily accessible single parameter derived from the intrinsic energy barriers, which fully specifies the potential diversity of metals. Based entirely on this parameter, a simple deformation mode diagram is shown to delineate a series of convenient design criteria, which clarifies a wide area of material functionality by texture control.planar fault | twinning | slip | molecular dynamics E lastic deformation of metals is fully described by Hooke's law, connecting stress and strain via the usual elastic parameters. In contrast, plasticity is a property that originates from dislocations and involves transitions over various competing energy barriers. A phenomenological description of the plastic regime based merely on the stacking fault energy (SFE) has been widely used by material scientists (1-11), even though it is not at all clear whether such an equilibrium property can really capture the complexity of plastic deformation. To try to mend this situation, researchers have introduced the so-called generalized planar fault (GPF) energy, which comprises several intrinsic energy barriers (IEBs) and thus provides detailed information on the deformation process itself (12, 13). Nevertheless, the GPF energy has not yet been fully recognized because of its inherent difficulty in experimental validation (14). In the present paper we solve this and introduce an approach that is fully transparent, where there are no such ambiguities.Face-centered cubic (fcc) metals possess three distinct deformation mechanisms: stacking fault (SF), twinning (TW), and full slip (SL) (2,(5)(6)(7)15). Many studies tried to relate the deformation of fcc metals to the GPF energy. For example, the competition between TW and SL was explained by a relative change between the intrinsic energy barriers, assuming the activation of the lowest barrier mode (16)(17)(18). However, such a simplified picture was found to be inadequate to elucidate the simultaneous activation of different modes seen in experiments (2,5,6,15). It has emerged that additional factors should be taken into account in conjunction with the GPF energy for describing the deformation behavior.The microstructure of materials, such as grain size and orientation, is known to in...

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Texture of Nanocrystalline Nickel: Probing the Lower Size Limit of Dislocation Activity

Cited by 102 publications

References 32 publications

Detecting grain rotation at the nanoscale

Detecting grain rotation at the nanoscale

Engineered inorganic core/shell nanoparticles

Theory for plasticity of face-centered cubic metals

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