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Author: Jinyu Zhang Publisher: ISBN: Category : Science Languages : en Pages :
Book Description
The aim of this chapter is to shed light on the effects of grain boundary segregation on microstructural evolution in nanostructured metallic materials as well as on their mechanical properties. Several key topics will be covered. First, a brief explanation of mechanical stress-driven grain growth in nanostructured Al, Ni, and Cu thin films will be provided in terms of a deformation mechanism map. It will become clear that the excess energy of grain boundaries enable the nanostructured metals to suffer from significant microstructure evolution via dislocation-boundary interactions during plastic deformation even at room temperature. Manipulation of grain boundary structures/properties via dopants segregation at grain boundaries to inhibit grain coalescence associated with remarkably enhanced mechanical properties is then discussed in three representative binary Cu-based systems, id est, Cu-Zr, Cu-Al, and Cu-W. This is finally followed by a summary of this chapter.
Author: Jinyu Zhang Publisher: ISBN: Category : Science Languages : en Pages :
Book Description
The aim of this chapter is to shed light on the effects of grain boundary segregation on microstructural evolution in nanostructured metallic materials as well as on their mechanical properties. Several key topics will be covered. First, a brief explanation of mechanical stress-driven grain growth in nanostructured Al, Ni, and Cu thin films will be provided in terms of a deformation mechanism map. It will become clear that the excess energy of grain boundaries enable the nanostructured metals to suffer from significant microstructure evolution via dislocation-boundary interactions during plastic deformation even at room temperature. Manipulation of grain boundary structures/properties via dopants segregation at grain boundaries to inhibit grain coalescence associated with remarkably enhanced mechanical properties is then discussed in three representative binary Cu-based systems, id est, Cu-Zr, Cu-Al, and Cu-W. This is finally followed by a summary of this chapter.
Author: Pavel Lejcek Publisher: Springer Science & Business Media ISBN: 3642125050 Category : Technology & Engineering Languages : en Pages : 249
Book Description
Grain boundaries are important structural components of polycrystalline materials used in the vast majority of technical applications. Because grain boundaries form a continuous network throughout such materials, their properties may limit their practical use. One of the serious phenomena which evoke these limitations is the grain boundary segregation of impurities. It results in the loss of grain boundary cohesion and consequently, in brittle fracture of the materials. The current book deals with fundamentals of grain boundary segregation in metallic materials and its relationship to the grain boundary structure, classification and other materials properties.
Author: I. Sabirov Publisher: Springer ISBN: 3319195999 Category : Technology & Engineering Languages : en Pages : 125
Book Description
This book presents a multifunctional approach to the design of bulk nanostructured metals through severe plastic deformation (SPD). Materials engineering has traditionally involved selecting a suitable material for a given application. However, modern engineering frequently requires materials with a set of multifunctional, often conflicting properties: Enhanced mechanical properties need to be combined with improved physical (electrical, magnetic, etc.) and/or chemical (corrosion resistance, biocompatibility) properties. So disparate materials properties need to be engineered and optimized simultaneously. These requirements have created a paradigm shift in which the classical materials selection approach is replaced by design of material microstructures to achieve certain performance requirements, subject to constraints on individual properties such as strength, conductivity, and corrosion resistance. Written by researchers at the forefront of this new materials design approach, the present volume provides a comprehensive introduction to multifunctional design of bulk nanostructured materials, with applications ranging from hydrogen storage to construction engineering.
Author: Michael Andrew Gibson (Ph. D.) Publisher: ISBN: Category : Languages : en Pages : 266
Book Description
Metals with grain sizes below 100 nanometers exhibit remarkable hardness [1], wear resistance [2], and superplastic forming behavior [3], in addition to changes in many other properties. These materials are thus of technological interest as structural materials. However, the excess free energy associated with grain boundary formation drives rapid grain growth in pure nanostructured metals at low homologous temperatures [4], preventing traditional (hot) forming and consolidation techniques and restricting practical usage. Such microstructural instability can be suppresed through alloying; thermally stable nanostructured metals can be designed through judicious choice of segregating alloying elements [5, 6, 7]. However, it is not known to what extent these effects are thermodynamic versus kinetic in origin. In order to advance understanding of nanostructure stabilization, in the first part of this thesis, I define general, thermodynamic limits on grain size stabilization via segregation in metals and provide specific thermodynamic models for grain size stabilization of polycrystals via alloying for use in future alloy design. While grain boundary segregation is desirable to inhibit grain growth, such segregation is typically associated with grain boundary embrittlement [8]. In the latter part of this thesis, I demonstrate general principles for the design thermally stable nanocrystalline metals without compromising grain boundary cohesion. More specifically, I create an analytical model of grain boundary embrittlement at equilibrium segregation; construct the largest database on grain boundary and surface segregation energies to date; and utilize this database of segregation energies to quantitatively confirm and deny hypotheses regarding the driving forces for surface segregation, grain boundary segregation, and grain boundary embrittlement. The specific results of this thesis should be useful to metallurgists in understanding and designing grain boundary and surface chemistry, and in designing materials resistant to grain boundary decohesion. The quantitative methods developed in this thesis should be useful to the broader materials community as a whole.
Author: Tomasz Tański Publisher: BoD – Books on Demand ISBN: 9535128612 Category : Science Languages : en Pages : 186
Book Description
This book contains eight chapters with original and innovative research studies in the field of grain boundaries. The results presented in the chapters of this book are very interesting and inspiring. This book will be very valuable to all researchers who are interested in the influence of grain boundaries on the structure and different kinds of properties of engineering materials. This book is also addressed to students and professional engineers working in the industry as well as to specialists who pay attention to all aspects related to grain boundaries and their impact on the various properties of innovative materials. The chapters of this book were developed by respected and well-known researchers from different countries.
Author: Yu R. Kolobov Publisher: Cambridge Int Science Publishing ISBN: 1904602177 Category : Technology & Engineering Languages : en Pages : 247
Book Description
The authors examine the main relationships of the process of grain boundary diffusion in bicrystals, coarse-grained polycrystals and nanostructured materials. The results of investigations of diffusion-related processes of recovery, recystallisation and development of plastic deformation in creep, static and cyclic loading in bulk nanostructured materials produced by high-intensity plastic deformation are presented.
Author: Amirhossein Khalajhedayati Publisher: ISBN: 9781321996067 Category : Languages : en Pages : 127
Book Description
Nanocrystalline metals have been the focus of current literature due to their interesting mechanical properties. This is a result of having nanometer sized grains and high volume fraction of grain boundaries. While these materials have high strength, the large number of boundaries is also responsible for the limited ductility and thermal instability often observed for nanocrystalline systems. Despite the current efforts in the literature, these challenges still prevent widespread use of nanocrystalline metals in real engineering applications. In this thesis, we study these problems by focusing on tailoring the grain boundary structure and chemistry and propose a methodology that can be used to mitigate those challenges. First, we study the plastic flow and failure as a function of grain boundary volume fraction (i.e., grain size) using microcompression in a nanocrystalline Ni-W. Since grain boundary physics are extremely important here, we also study how the relaxation of nonequilibrium grain boundaries affects failure. We show that nanocrystalline metals with larger grain boundary volume fractions and relaxed boundary structures are stronger, but also more likely to fail prematurely through catastrophic shear banding. We also show that shear banding can create a dynamic microstructure leading to grain coarsening. A major take-away from this work is that disordered grain boundaries can actually be beneficial. Therefore, in the next study we introduce amorphous complexions, highly disordered grain boundaries, through grain boundary doping as an all-in-one solution to design against failure and thermal instability. We use nanocrystalline Cu with the addition of Zr as our model system to explore complexion engineering in these materials. High resolution transmission electron microscopy in conjunction with energy dispersive x-ray spectroscopy demonstrates segregation of Zr to the boundaries of Cu-Zr alloys created with mechanical alloying. This provided evidence for the formation of amorphous grain boundaries complexions under certain conditions. Microcompression and in-situ bending experiments are then used to quantify the effect of doping on mechanical behavior. Finally, our results show that strength, strain-to-failure, failure mode, and thermal stability can be controlled with boundary doping. The proposed methodology described here is rather general and can be applied to other material systems to make bulk nanocrystalline metals with improved mechanical properties.
Author: Oleg N. Senkov Publisher: Springer Science & Business Media ISBN: 1402021127 Category : Technology & Engineering Languages : en Pages : 451
Book Description
In the fall of 1998, Prof. Sergey Firstov invited me to the Frantcevych Institute for Problems of Materials Science (IPMS) in Kyiv, Ukraine to discuss possible collaborations in the area of advanced metals research. During this visit, a strong mutual interest was evident in a broad range of structural metals technologies, and a quick friendship was established. Countless subsequent emails and a reciprocal visit to the U. S Air Force Research Laboratory by Prof. Firstov and a team of scientists from IPMS ensued to discuss and detail a broad collaboration in the area of structural metals. Two years after the initial visit, a major investment by the U. S. Air Force Office of Scientific Research (AFOSR) was established to pursue the technologies defined by these interactions. The annual reviews of the AFOSR Ukrainian Metals Initiative were held in late May, a most beautiful time in Kyiv when the lilacs are in bright display and the air is scented with the smell of falling blossoms from the chestnut trees that line the major streets and many parks. The sunny days and mild evenings provide a welcome break from winter, and on weekend evenings festive crowds spill onto the Khreshchatyk, Kyiv’s downtown boulevard, to listen to street musicians, watch jugglers and comedians, or simply to celebrate with friends. The annual reviews featured long days of intensive discussion of technical progress, followed in the evenings by the warm hospitality of the Ukrainian hosts.
Author: T. Daniel Thangadurai Publisher: Springer Nature ISBN: 303026145X Category : Technology & Engineering Languages : en Pages : 210
Book Description
This book discusses the early stages of the development of nanostructures, including synthesis techniques, growth mechanisms, the physics and chemistry of nanostructured materials, various innovative characterization techniques, the need for functionalization and different functionalization methods as well as the various properties of nanostructured materials. It focuses on the applications of nanostructured materials, such as mechanical applications, nanoelectronics and microelectronic devices, nano-optics, nanophotonics and nano-optoelectronics, as well as piezoelectric, agriculture, biomedical and, environmental remediation applications, and anti-microbial and antibacterial properties. Further, it includes a chapter on nanomaterial research developments, highlighting work on the life-cycle analysis of nanostructured materials and toxicity aspects.
Author: Jinyu Zhang
Author: Jinyu Zhang
Author: Pavel Lejcek
Author: I. Sabirov
Author: Michael Andrew Gibson (Ph. D.)
Author: Tomasz Tański
Author: Yu R. Kolobov
Author: Amirhossein Khalajhedayati
Author: Oleg N. Senkov
Author: T. Daniel Thangadurai
Author: Donald McLean