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Nanostructure Stabilization And Mechanical Behavior Of Binary Nanocrystalline Alloys
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Book Synopsis Nanostructure Stabilization and Mechanical Behavior of Binary Nanocrystalline Alloys by : Jason R. Trelewicz
Download or read book Nanostructure Stabilization and Mechanical Behavior of Binary Nanocrystalline Alloys written by Jason R. Trelewicz and published by . This book was released on 2008 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: The unique mechanical behavior of nanocrystalline metals has become of great interest in recent years, owing to both their remarkable strength and the emergence of new deformation physics at the nanoscale. Of particular interest has been the breakdown in Hall-Petch strength scaling, which is frequently attributed by atomistic simulations to a mechanistic shift to interface dominated plasticity. Experimental validation has been less abundant, primarily due to the processing challenges associated with achieving homogeneous nanocrystalline samples suitable for mechanical testing. Alloying has been proposed as a potential route to high-quality nanocrystalline metals, although choice of an appropriate alloy system, based on available thermodynamic data, remains elusive. In this thesis, we propose a thermodynamic model for nanostructure stabilization that derives from the energetic state variables characteristic of binary alloys. These modeling results motivate the study of Ni-W alloys in particular, which may be synthesized via aqueous electrodeposition, accessing grain sizes across the entire Hall-Petch breakdown regime as characterized by x-ray diffraction and transmission electron microscopy. Ambient temperature nanoindentation testing is employed to evaluate the mechanical behavior of the as-deposited alloys, assessing the nature of flow, the rate sensitivity, and pressure sensitivity of deformation, with emphasis on property inflections required to bridge the behavior of nanocrystalline metals to amorphous solids. The rate sensitivity, in particular, demonstrates an inherent dependence on nanocrystalline grain size, exhibiting a maximum in the vicinity of the Hall-Petch breakdown as a consequence of a shift to glass-like shear localization. In light of this finding, we study the Hall-Petch breakdown at high strain rates, and show that an "inverse Hall-Petch" weakening regime emerges at high rates. Additional effects from structural relaxation are investigated, and illustrated to strongly influence the strength scaling behavior and shift to inhomogeneous flow. Relaxed samples are also subjected to elevated temperature indentation tests, and the results discussed in the context of thermally-activated plasticity, thus providing a more quantitative analysis of the nanoscale deformation mechanisms.
Book Synopsis The Effect of Solutes on Interface Structure and Microstructural Stability in Binary, Nanocrystalline Alloys by : Jonathan Priedeman
Download or read book The Effect of Solutes on Interface Structure and Microstructural Stability in Binary, Nanocrystalline Alloys written by Jonathan Priedeman and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stabilizing a nanocrystalline material against grain growth is necessary to preserve the nanostructure and associated strength while experiencing conditions experienced during manufacturing and/or service. This work examines the structures and stability provided by solutes in different alloys. First, a platinum-gold alloy thin film is examined during in-situ annealing where observations of a faceted grain boundary structure are made. Atomistic simulations reveal that segregation of gold to that grain boundary stabilize such a structure. Second, a bulk copper-niobium alloy is plastically deformed at elevated temperature. The nanostructure of the alloy is preserved, indicating good stability. The strength of the niobium-doped alloy, however, is more sensitive to temperature than a related copper-tantalum alloy. This sensitivity is found to be a result of the oxidation behavior of the solutes: theoretical calculations of the misfit strengthening provided by these oxide precipitates reveal greater temperature sensitivity than either the niobium or tantalum precipitates. Third, a bulk copper-hafnium alloy is also plastically deformed at elevated temperature, and the nanostructure is also retained. Here the hafnium was processed as a conformal coating over the copper powder prior to consolidation rather than use of an elemental powder-powder mixing. The copper-hafnium alloy has good low-temperature strength, but begins deforming by grain boundary mediated mechanisms at much lower temperatures compared to copper-tantalum and copper-niobium. Again, the precipitates contribute to this behavior, as the hafnium oxidizes to form a monoclinic hafnium dioxide. This oxide provides good resistance to dislocation propagation but does not reinforce grain boundaries due to lack of coherency. Thus, in all three alloys studied, the solute behavior as it seeks to achieve local equilibrium has profound effects on observed structural evolution (and mechanical response).
Book Synopsis Design of Stable Nanostructure Configurations in Ternary Alloys by : Wenting Xing (Ph. D.)
Download or read book Design of Stable Nanostructure Configurations in Ternary Alloys written by Wenting Xing (Ph. D.) and published by . This book was released on 2018 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of stable nanocrystalline binary alloys, which possess a large volume fraction of grain boundaries at elevated temperatures, is a promising route to high yield strength materials. Previous studies have focused on alloying by selecting solute elements that segregate at grain boundaries to stabilize the nanostructure. A selection criterion has been established for designing stable binary nanocrystalline materials. This thesis explores the extension of this concept to the design of multicomponent nanostructured systems. In contrast to the simplicity of a binary system where not many topological possibilities are accessible, multicomponent nanostructured systems are shown to occupy a vast space where the large majority of interesting configurations will be missed by a regular solution approximation. This thesis describes research to develop a conceptual basis for the thermodynamic properties of multicomponent nanocrystalline alloys, and to design interesting ternary configurations not accessible in binary systems. The conditions necessary to achieve the desired nanostructure configurations are developed in a model that takes solute interactions into consideration. Based on the model, we performed a systematic case study on one alloy system expected to exhibit nanocrystalline stability: Pt-Pd-Au. As a control, two binary systems (Pt-Au, Pt-Pd) were produced for comparison. While a uniform distribution of Pd is observed in binary Pt-Pd alloys at 400 °C, the results from scanning transmission electron microscopy (STEM) reveal that Pd segregation behavior was induced by the Au grain boundary segregation in the ternary system at 400 °C. Our work on induced co-segregation behavior of Pt-Pd-Au alloy is just a simple example of solute interaction in nanocrystalline alloys. Our approach more generally presents a new design framework to control the complex configurations possible in nanocrystalline materials by alloying element selection.
Book Synopsis Nanostructured Metals and Alloys by : S H Whang
Download or read book Nanostructured Metals and Alloys written by S H Whang and published by Elsevier. This book was released on 2011-03-22 with total page 840 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tensile strength, fatigue strength and ductility are important properties of nanostructured metallic materials, which make them suitable for use in applications where strength or strength-to-weight ratios are important. Nanostructured metals and alloys reviews the latest technologies used for production of these materials, as well as recent advances in research into their structure and mechanical properties. One of the most important issues facing nanostructured metals and alloys is how to produce them. Part one describes the different methods used to process bulk nanostructured metals and alloys, including chapters on severe plastic deformation, mechanical alloying and electrodeposition among others. Part two concentrates on the microstructure and properties of nanostructured metals, with chapters studying deformation structures such as twins, microstructure of ferrous alloys by equal channel angular processing, and characteristic structures of nanostructured metals prepared by plastic deformation. In part three, the mechanical properties of nanostructured metals and alloys are discussed, with chapters on such topics as strengthening mechanisms, nanostructured metals based on molecular dynamics computer simulations, and surface deformation. Part four focuses on existing and developing applications of nanostructured metals and alloys, covering topics such as nanostructured steel for automotives, steel sheet and nanostructured coatings by spraying. With its distinguished editor and international team of contributors, Nanostructured metals and alloys is a standard reference for manufacturers of metal components, as well as those with an academic research interest in metals and materials with enhanced properties.
Book Synopsis Amorphous-Nanocrystalline Alloys by : A.M. Glezer
Download or read book Amorphous-Nanocrystalline Alloys written by A.M. Glezer and published by CRC Press. This book was released on 2017-12-06 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt: Amorphous-nanocrystalline alloys are a relatively new class of materials born from the rapid development of new technologies and different methods of producing amorphous and nanocrystalline powders and films, compacting, melt quenching, megaplastic deformation, implantation, laser, plasma, and other high-energy methods. This book considers methods of producing these materials (melt quenching, controlled crystallization, deformation effect, and pulse treatments (photon, laser and ultrasound), spraying thin films, and ion implantation). Theoretical and experimental studies describe plastic deformation mechanisms and physico-mechanical properties. Practical applications are also presented.
Book Synopsis Transmission Electron Microscopy by : C. Barry Carter
Download or read book Transmission Electron Microscopy written by C. Barry Carter and published by Springer. This book was released on 2016-08-24 with total page 543 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text is a companion volume to Transmission Electron Microscopy: A Textbook for Materials Science by Williams and Carter. The aim is to extend the discussion of certain topics that are either rapidly changing at this time or that would benefit from more detailed discussion than space allowed in the primary text. World-renowned researchers have contributed chapters in their area of expertise, and the editors have carefully prepared these chapters to provide a uniform tone and treatment for this exciting material. The book features an unparalleled collection of color figures showcasing the quality and variety of chemical data that can be obtained from today’s instruments, as well as key pitfalls to avoid. As with the previous TEM text, each chapter contains two sets of questions, one for self assessment and a second more suitable for homework assignments. Throughout the book, the style follows that of Williams & Carter even when the subject matter becomes challenging—the aim is always to make the topic understandable by first-year graduate students and others who are working in the field of Materials Science Topics covered include sources, in-situ experiments, electron diffraction, Digital Micrograph, waves and holography, focal-series reconstruction and direct methods, STEM and tomography, energy-filtered TEM (EFTEM) imaging, and spectrum imaging. The range and depth of material makes this companion volume essential reading for the budding microscopist and a key reference for practicing researchers using these and related techniques.
Book Synopsis Bulk Metallic Glasses by : C. Suryanarayana
Download or read book Bulk Metallic Glasses written by C. Suryanarayana and published by CRC Press. This book was released on 2017-11-22 with total page 543 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reflecting the fast pace of research in the field, the Second Edition of Bulk Metallic Glasses has been thoroughly updated and remains essential reading on the subject. It incorporates major advances in glass forming ability, corrosion behavior, and mechanical properties. Several of the newly proposed criteria to predict the glass-forming ability of alloys have been discussed. All other areas covered in this book have been updated, with special emphasis on topics where significant advances have occurred. These include processing of hierarchical surface structures and synthesis of nanophase composites using the chemical behavior of bulk metallic glasses and the development of novel bulk metallic glasses with high-strength and high-ductility and superelastic behavior. New topics such as high-entropy bulk metallic glasses, nanoporous alloys, novel nanocrystalline alloys, and soft magnetic glassy alloys with high saturation magnetization have also been discussed. Novel applications, such as metallic glassy screw bolts, surface coatings, hyperthermia glasses, ultra-thin mirrors and pressure sensors, mobile phone casing, and degradable biomedical materials, are described. Authored by the world’s foremost experts on bulk metallic glasses, this new edition endures as an indispensable reference and continues to be a one-stop resource on all aspects of bulk metallic glasses.
Book Synopsis Mechanical Behaviour of Nanostructured Materials by : D.G. Morris
Download or read book Mechanical Behaviour of Nanostructured Materials written by D.G. Morris and published by Trans Tech Publications Ltd. This book was released on 1998-04-06 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: The investigation of nanocrystalline materials has been an extremely active field during the past two decades as it promises to yield new and exciting properties, which will both test the scientific understanding of the behaviour of materials in general, and offer new scope for applications. While considerable progress has been made in basic understanding, the shift from fundamental science to technological application has been slow, especially with regard to exploitation of the mechanical behaviour of these materials.
Book Synopsis Mechanical Properties of Nanocrystalline Materials by : James C. M. Li
Download or read book Mechanical Properties of Nanocrystalline Materials written by James C. M. Li and published by CRC Press. This book was released on 2011-09-02 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book concentrates on both understanding and development of nanocrystalline materials. The original relation that connects grain size and strength, known as the Hall-Petch relation, is studied in the nanometer grain size region. The breakdown of such a relation is a challenge. Why and how to overcome it? Is the dislocation mechanism still operating when the grain size is very small, approaching the amorphous limit? How do we go from the microstructure information to the continuum description of the mechanical properties?
Book Synopsis Microstructural Stability and Mechanical Behavior of Nanostructured Ni by : Jeremy Thornton
Download or read book Microstructural Stability and Mechanical Behavior of Nanostructured Ni written by Jeremy Thornton and published by . This book was released on 2006 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Plastic Deformation in Nanocrystalline Materials by : Mikhail Gutkin
Download or read book Plastic Deformation in Nanocrystalline Materials written by Mikhail Gutkin and published by Springer. This book was released on 2010-12-01 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: It seems there is no special need to comment on the term 'nanostructure' now, when one often meets the 'nano' words not only in scientific journals but even in newspapers. Moreover, today they are even to be heard in TV and radio programmes. In academic science, where the terms 'nanostructure' and 'nan otechnology' have been extremely popular since the early 1990s, they have been successfully extended to the sphere of economics and business, and now to politics. This is quite natural because nanostructures and nanotechnolo gies will surely serve as a basis for the most advanced and highest technology production in the nearest and probably also the remote future. Hence, the struggle to create and occupy its markets is already under way. In this respect, it is of great interest to review data on the dynamics of U. S. Federal Goverment expenditure for nanotechnology [1,2]. In the fiscal years 1997 and 2002, expenditure was approximately US$116 and US$ 697 million, respectively. In the fiscal year 2004, the President's request for US federal in vestment in nanoscale science, engineering and technology is about US$ 849 million [2]. The indicative budget allocated to the Thematic Priority enti tled 'Nanotechnologies and nanosciences, knowledge-based multifunctional materials and new production processes and devices' for the duration 2002- 2006 of the sixth EU Framework Programme for Research and Technological Development is EUR 1300 million [3].
Book Synopsis Structural Nanocrystalline Materials by : Carl C. Koch
Download or read book Structural Nanocrystalline Materials written by Carl C. Koch and published by Cambridge University Press. This book was released on 2007-05-31 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanocrystalline materials exhibit exceptional mechanical properties, representing an exciting new class of structural materials for technological applications. The advancement of this important field depends on the development of new fabrication methods, and an appreciation of the underlying nano-scale and interface effects. This authored book addresses these essential issues, presenting for the first time a fundamental, coherent and current account at the theoretical and practical level of nanocrystalline and nanocomposite bulk materials and coatings. The subject is approached systematically, covering processing methods, key structural and mechanical properties, and a wealth of applications. This is a valuable resource for graduate students studying nanomaterials science and nanotechnologies, as well as researchers and practitioners in materials science and engineering.
Book Synopsis Design of a Stable Nanocrystalline Alloy by : Heather Ann Murdoch
Download or read book Design of a Stable Nanocrystalline Alloy written by Heather Ann Murdoch and published by . This book was released on 2013 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanocrystalline materials are inherently unstable due to their high material fraction of grain boundaries, preventing their improved properties from being used in application. To stabilize the nanoscale grain size against rampant growth, past literature has proposed lowering the grain boundary energy through solute segregation to the boundaries. This approach has seen varied experimental success, using a metric of segregation strength to select an alloying element. In those alloys were some measure of stabilization is gained through alloying, precipitation of a second phase disrupts the necessary segregation state and triggers grain growth. This work considers the total stability of a nanocrystalline alloy -- both stability against grain growth and stability against second phase precipitation -- by examining the changes in free energy associated with segregation and nanostructuring. It is discovered that the relationship of segregation and mixing enthalpies for a particular system dictates the nanocrystalline stability of the alloy. Nanocrystalline stability maps are constructed for several conditions that can be used to predict an alloy's ability to support a nanostructure. Also revealed by the generation of stability maps are new types of stable nanocrystalline phases - in addition to the expected nano-phase stabilized by solute decoration of the grain boundary, a solute-rich nanocrystalline phase is expected to be stable under some conditions, as is an amorphous phase. To connect material systems to the results predicted by this work, a new model for the enthalpy of segregation was derived.
Book Synopsis Atomistic Simulation Study of Nickel Solute Segregation and Mechanical Behavior in Nanocrystalline Fcc, Bcc and Hcp Binary Alloys by : Ève-Audrey Picard
Download or read book Atomistic Simulation Study of Nickel Solute Segregation and Mechanical Behavior in Nanocrystalline Fcc, Bcc and Hcp Binary Alloys written by Ève-Audrey Picard and published by . This book was released on 2021 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanocrystalline metals and alloys have been proven to possess unprecedentedly higher tensile strength than coarse-grained conventional metals. The extreme grain refinement in nanocrystalline metals, however, negatively affects these materials by reducing their ductility through grain-boundary embrittlement and shear localization mechanisms that are promoted by segregation of solute atoms to the interfaces. Different segregation behaviors described in the literature can be divided into either heterogeneous or homogeneous types. Yet current understanding of the impact of solute atom arrangements within grain boundary networks on mechanical properties of cubic and hexagonal nanocrystals remains limited. In this thesis, hybrid Monte-Carlo and molecular dynamics simulations were used to study the segregation behavior of Ni solute atoms in polycrystals made of FCC Ag-Ni, FCC Al-Ni, BCC Nb-Ni, and HCP Zr-Ni alloys. Solute segregation in 4 binary alloys with a constant solute content of 4 at.% Ni was simulated and quantified at the same homologous temperature and at their respective maximum solubility temperature. A spectrum of segregation configurations varying from fully heterogeneous to fully homogeneous was found: Pure heterogeneous segregation (Ag96Ni4 500 K), homogeneous segregation with second-phase precipitates (Al96Ni4 378 K, Nb96Ni4 1110 K), homogeneous segregation with small-scale Ni clusters (Nb96Ni4 1564 K, Zr96Ni4 464 K), and pure homogeneous segregation with amorphous intergranular films (Al96Ni4 913 K, Zr96Ni4 1118 K). These differences in segregation behavior are shown to lead to significant variations in stress-strain response for each alloy. It is found that segregation involving the presence of grain-boundary precipitates with homogeneous segregation behavior promoted the most significant shear localization.
Book Synopsis Advanced Mechanical Properties and Deformation Mechanisms of Bulk Nanostructured Materials by : Yonghao Zhao
Download or read book Advanced Mechanical Properties and Deformation Mechanisms of Bulk Nanostructured Materials written by Yonghao Zhao and published by Trans Tech Publications. This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume is indexed by Thomson Reuters BCI (WoS).Bulk nanostructured (NS) materials have emerged as a new class of materials having unusual structures and properties. As a result, they have attracted considerable attention in recent years. Bulk NS materials are single or multi-phase polycrystals with a nanoscale grain size and can usually be classified into nanocrystalline (
Book Synopsis Nanostructures: Synthesis, Functional Properties and Application by : Thomas Tsakalakos
Download or read book Nanostructures: Synthesis, Functional Properties and Application written by Thomas Tsakalakos and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 694 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Advanced Study Institute on Synthesis, Functional Properties and Applications of Nanostructures, held at the Knossos Royal Village, Heraklion, Crete, Greece, July 26, 2002 - August 4, 2002, successfully reviewed the state-of-the-art of nanostructures and nanotechnology. It was concluded that Nanotechnology is widely agreed to be the research focus that will lead to the next generation of breakthroughs in science and engineering. There are three cornerstones to the expectation that Nanotechnology will yield revolutionary advances in understanding and application: • Breakthroughs in properties that arise from materials fabricated from the nanoscale. • Synergistic behavior that arise from the combination of disparate types of materials (soft vs. hard, organic vs. inorganic, chemical vs. biological vs. solid state) at the nanoscale. • Exploitation of natural (e.g. chemical and biological) assembly mechanisms that can accomplish structural control at the nanoscale. It is expected that this will lead to paradigms for assembling bio-inspired functional systems that accomplish desirable properties that are either unavailable or prohibitively expensive using top-down approaches.
