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Languages : en
Pages :
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Book Description
Layered composites of Cu/Nb with incoherent interfaces achieve very high strength levels. Interfaces play a crucial role in materials strength by acting as barriers to slip. Atomistic models of Cu/Nb bilayers are used to explore the origins of this resistance. The models clearly show that dislocations near an interface experience an attraction toward the interface. This attraction is caused by shear of the interface induced by the stress field of the dislocation. More importantly, atomistic simulations also reveal that interfacial dislocations easily move in interfaces by both glide and climb. Integrating these findings into a micro-scale model, we develop a three-dimensional crystal elastic-plastic model to describe the mechanical behavior of nanoscale metallic multi layers.
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ISBN:
Category :
Languages : en
Pages :
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Book Description
Layered composites of Cu/Nb with incoherent interfaces achieve very high strength levels. Interfaces play a crucial role in materials strength by acting as barriers to slip. Atomistic models of Cu/Nb bilayers are used to explore the origins of this resistance. The models clearly show that dislocations near an interface experience an attraction toward the interface. This attraction is caused by shear of the interface induced by the stress field of the dislocation. More importantly, atomistic simulations also reveal that interfacial dislocations easily move in interfaces by both glide and climb. Integrating these findings into a micro-scale model, we develop a three-dimensional crystal elastic-plastic model to describe the mechanical behavior of nanoscale metallic multi layers.
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Languages : en
Pages : 16
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Book Description
The development of multilayer structures has been driven by a wide range of commercial applications requiring enhanced material behaviors. Innovations in physical vapor deposition technologies, in particular magnetron sputtering, have enabled the synthesis of metallic-based structures with nanoscaled layer dimensions as small as one-to-two monolayers. Parameters used in the deposition process are paramount to the Formation of these small layer dimensions and the stability of the structure. Therefore, optimization of the desired material properties must be related to assessment of the actual microstructure. Characterization techniques as x-ray diffraction and high resolution microscopy are useful to reveal the interface and layer structure-whether ordered or disordered crystalline, amorphous, compositionally abrupt or graded, and/or lattice strained Techniques for the synthesis of metallic multilayers with subnanometric layers will be reviewed with applications based on enhancing material behaviors as reflectivity and magnetic anisotropy but with emphasis on experimental studies of mechanical properties.
Author: Vasyl Michael Harik
Publisher: Springer Science & Business Media
ISBN: 940170385X
Category : Technology & Engineering
Languages : en
Pages : 241
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Book Description
An outstanding feature of this book is a collection of state-of-the-art reviews written by leading researchers in the nanomechanics of carbon nanotubes, nanocrystalline materials, biomechanics and polymer nanocomposites. The structure and properties of carbon nanotubes, polycrystalline metals, and coatings are discussed in great details. The book is an exceptional resource on multi-scale modelling of metals, nanocomposites, MEMS materials and biomedical applications. An extensive bibliography concerning all these topics is included. Highlights on bio-materials, MEMS, and the latest multi-scale methods (e.g., molecular dynamics and Monte Carlo) are presented. Numerous illustrations of inter-atomic potentials, nanotube deformation and fracture, grain rotation and growth in solids, ceramic coating structures, blood flows and cell adhesion are discussed. This book provides a comprehensive review of latest developments in the analysis of mechanical phenomena in nanotechnology and bio-nanotechnology.
Author: Arief Suriadi Budiman
Publisher: Springer Nature
ISBN: 9811567204
Category : Science
Languages : en
Pages : 254
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Book Description
This book addresses issues pertinent to mechanics and stress generation, especially in recent advanced cases of technology developments, spanning from micrometer interconnects in solar photovoltaics (PV), next-gen energy storage devices to multilayers of nano-scale composites enabling novel stretchable/flexible conductor technologies. In these cases, the mechanics of materials have been pushed to the extreme edges of human knowledge to enable cutting-edge, unprecedented functionalities and technological innovations. Synchrotron X-ray diffraction, in situ small-scale mechanical testing combined with physics-based computational modeling/simulation, has been widely used approaches to probe these mechanics of the materials at their extreme limits due to their recently discovered distinct advantages. The techniques discussed in this manuscript are highlights specially curated from the broad body of work recently reported in the literature, especially ones that the author had led the pursuits at the frontier himself. Extreme stress generation in these advanced material leads to often new failure modes, and hence, the reliability of the final product is directly affected. From the recent topics and various advanced case studies covered in this book, the reader gets an updated knowledge of how new mechanics can and has been applied in Design-for-Reliability (DfR) for some of the latest technological innovations known in our modern world. Further, this also helps in building better designs, which may avoid the pitfalls of the current practiced trends.
Author: Shuai Shao
Publisher:
ISBN: 9781267477316
Category :
Languages : en
Pages :
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Book Description
The goal of this thesis is to understand the interaction between dislocations and various metallic interfaces in nanoscale metallic multilayers (NMM). At lower strain rates, this mean understanding the effect of interfaces to the strain hardening of the NMMs; at higher strain rates, this means the effect of the interfaces on the spallation strengths of the NMMs. NMMs possess ultra-high strength level which is owing to the interactions between single dislocations (i.e. no pile-up) and interfaces. In this thesis, aiming at the goal, using atomistic simulations several nanoscale metallic multilayers subjected to different loading conditions and strain rates are being considered.
Author:
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ISBN:
Category :
Languages : en
Pages : 13
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Book Description
In complex loading conditions (e.g. sliding contact), mechanical properties, such as strain hardening and initial hardness, will dictate the long-term performance of materials systems. With this in mind, the strain hardening behaviors of Cu/Nb nanoscale metallic multilayer systems were examined by performing nanoindentation tests within nanoscratch wear boxes and undeformed, as-deposited regions. Both the architecture and substrate influence were examined by utilizing three different individual layer thicknesses (2, 20, and 100 nm) and two total film thicknesses (1 and 10 [mu]m). After nano-wear deformation, multilayer systems with thinner layers showed less volume loss as measured by laser scanning microscopy. Additionally, the hardness of the deformed regions significantly rose with respect to the as-deposited measurements, which further increased with greater wear loads. Strain hardening exponents for multilayers with thinner layers (2 and 20 nm, n ≈ 0.018 and n ≈ 0.022 respectively) were less than was determined for 100 nm systems (n ≈ 0.041). These results suggest that singledislocation based deformation mechanisms observed for the thinner systems limit the extent of achievable strain hardening. This conclusion indicates that impacts of both architecture strengthening and strain hardening must be considered to accurately predict multilayer performance during sliding contact across varying length scales.
Author: Bharat Bhushan
Publisher: Springer Science & Business Media
ISBN: 3642311075
Category : Technology & Engineering
Languages : en
Pages : 1467
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Book Description
Nanomaterials attract tremendous attention in recent researches. Although extensive research has been done in this field it still lacks a comprehensive reference work that presents data on properties of different Nanomaterials. This Handbook of Nanomaterials Properties will be the first single reference work that brings together the various properties with wide breadth and scope.
Author: A. Chamberod
Publisher: Trans Tech Publications Ltd
ISBN: 303570452X
Category : Technology & Engineering
Languages : en
Pages : 648
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Book Description
This book contains a series of lectures given in a Summer School held in Aussois (France) in September 1989. It offers a global perspective on the current state-of-the-art in the rapidly emerging field of metallic multilayered structures.
Author: Firas Akasheh
Publisher:
ISBN: 9780549023258
Category :
Languages : en
Pages : 150
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Book Description
In this work, size effects and deformation mechanisms in nanoscale metallic multilayered (NMM) composites were studied. Existing models for the prediction of the dependence of strength of NMM composites on the individual layer thickness do not capture the experimentally observed dependence. Dislocation interactions have been suggested as a significant contributor to this discrepancy. Due to the complexity and multiplicity of dislocation interaction in real systems, the study started by examining the hardening effect and implications on the dislocation structure of two known-to-be significant dislocation interactions in NMM composites. The first is the interaction between a threading dislocation and orthogonally intersection interfacial dislocations. Dislocation dynamics (DD) analysis was employed and it was found that the strongest interaction occurs when the interacting dislocations are collinear and involves annihilation reactions and the formation of 90° dislocation bends at the interfaces, as commonly observed in experiments. The strength predictions indicate a strengthen increase of about 50%; however, they do not follow the experimentally observed trend. The second interaction to study was that between a threading dislocation and parallel interfacial dislocations. A semi-analytical energetic approach was employed and it was found that parallel interactions can lead to softening effect, as well as hardening effect depending on the relative sign of the Burgers vector of the threading and the parallel dislocations. It was also found that when the Burgers vectors are collinear, the interaction is stronger. A comparison with the measured strength of real multilayered system shows that accounting for parallel interactions improves the strength predictions for an isolated glide dislocation, however that does not offer answers regarding the observed strength saturation when the individual layer thickness in the few nanometer range. Finally, large-scale DD simulations of NMM composites were performed. Such simulations naturally accounts for all the possible and complex interactions in a real system. The strength predictions of such simulations are in better qualitative agreement with experimental trends than any of the unit process. Nevertheless, more work is needed to validate the results by investigating different relaxation models to accomplish the initial dislocations structure used in subsequent loading. The simulations were also valuable in identifying dislocation mechanisms which can take place during the deformation.
Author: Young Kwon
Publisher: Springer Science & Business Media
ISBN: 0387363181
Category : Technology & Engineering
Languages : en
Pages : 634
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Book Description
This book presents the state-of-the-art in multiscale modeling and simulation techniques for composite materials and structures. It focuses on the structural and functional properties of engineering composites and the sustainable high performance of components and structures. The multiscale techniques can be also applied to nanocomposites which are important application areas in nanotechnology. There are few books available on this topic.
