Download or read book Deformation and Damage Process in Nanostructured Metallic Systems written by and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this reporting period, processing of nanostructured powders, consolidation of nanostructured powders, computer simulation, micro structural characterization, and mechanical deformation tests were carried out. The nanostructured powders and bulk nanostructured materials were produced successfully via optimization of processing parameters. The observed highly grain stability can be explained by a grain boundary pinning mechanism arising from the dispersoid particles as well as impurity segregation. The microstructures of the as- extruded and the deformed bulk nanocrystalline aluminum alloys were investigated using transmission electron microscopy. A nanoindentation technique and traditional mechanical tests as well as computer simulation were also used to evaluate the mechanical performance. A discrete dislocation dynamics model has been developed to bridge the gap between atomic simulations and continuum approaches. It has the potential to provide a rigorous description of the complex relationships between the macroscopic mechanical behavior of materials and the underlying fundamental physical mechanisms. The tensile test results showed that grain size effects, solid solution strengthening, Orowan strengthening and dislocation strengthening contribute significantly to the properties of the cryomilled Al alloys. The future work for the next period is also discussed in the report.

Download or read book An Experimental Study of Deformation and Fracture of a Nanostructured Metallic Material written by Nisrin Rizek Abdel Al and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The mechanical properties of materials strongly depend on their microstructure. Therefore, engineering the material's microstructure can lead to improving its mechanical properties. One method for enhancing the strength of metallic materials consists of refining the grain size down to the nanometer scale. Such nanostructured materials possess remarkable strength without using conventional metallurgical strengthening methods. However, this strength often comes at the expense of workhardening capacity, thus favoring flow localization and loss of ductility and toughness. The deformation behavior of nanostructured metallic materials has been extensively studied in the literature. However, little is known of their fracture behavior. In this study, the mechanical behavior of a nanostructured, nearly pure material is investigated in order to link processing conditions, microstructure, and fracture locus in stress space. With focus laid on BCC materials which can undergo a ductile-to-brittle transition, Interstitial- Free (IF) steel is chosen. The microstructure is refined using Severe Plastic Deformation (SPD) to achieve ultra-fine grain (UFG) materials with grain sizes in the range 100nm- 1 mu m. Equal Channel Angular Extrusion (ECAE) is used to obtain three types of UFG-IF steel microstructures by varying the extrusion rate and processing temperature. The deformation behavior is investigated for the three UFG materials using round smooth bars and is compared with the behavior of the as-received material. The damage behavior and the fracture mechanisms are studied using tensile round notched bars with varying notch radii. The findings indicate a remarkable combination of strength and notch ductility at room temperature, including for the material with the finest microstructure. They also point to the need for careful characterization of temperature effects before such materials can be considered in structural applications.

Download or read book Damage Tolerance and Mechanics of Interfaces in Nanostructured Metals written by Daniel J. Foley and published by . This book was released on 2017 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: The concept of interface driven properties in crystalline metals has been one of the most intensely discussed topics in materials science for decades. Since the 1980s researchers have been exploring the concept of grain boundary engineering as route for tuning properties such as fracture toughness and irradiation resistance. This is especially true in ultra-fine grained and nanocrystalline materials where grain boundary mediated properties become dominant. More recently, materials composed of hierarchical nanostructures, such as amorphous-crystalline nanolaminates, have attracted considerable attention due to their favorable properties, ease of manufacture and highly tunable microstructure. While both grain boundary engineering and hierarchical nanostructures have shown promise there are still questions remaining regarding the role of specific attributes of the microstructure (such as grain boundaries, grain/layer size and inter/intralayer morphology) in determining material properties. This thesis attempts to address these questions by using atomistic simulations to perform deformation and damage loading studies on a series of nanolaminate and bicrystalline structures. During the course of this thesis the roles of layer thickness, interlayer structure and interlayer chemistry on the mechanical properties of Ni-NiX amorphous-crystalline nanolaminates were explored using atomistic simulations. This thesis found that layer thickness/thickness ratio and amorphous layer chemistry play a crucial role in yield strength and Young's modulus. Analysis of the deformation mechanisms at the atomic scale revealed that structures containing single crystalline, crystalline layers undergo plastic deformation when shear transformation zones form in the amorphous layer and impinge on the amorphous-crystalline interface, leading to dislocation emission. However, structures containing nanocrystalline, crystalline layers (both equiaxed and columnar nanocrystalline) undergo plastic deformation through a combination of grain boundary sliding and grain boundary mediated dislocation nucleation. Since grain boundaries were found to play a critical role as sources and sinks for dislocations in amorphous-crystalline nanolaminates a follow-up study on the effect of grain boundary character on damage accumulation/accommodation in copper symmetric tilt grain boundaries was performed. This study found that grain boundaries will become saturated with damage, a state where grain boundary energy and grain boundary free volume oscillate about a plateau during continuous defect loading (vacancy, interstitial and frenkel pair loading were all considered). Further, grain boundary character (specifically equilibrium grain boundary energy) was strongly correlated to the damage accommodation behavior of grain boundaries in copper. Finally, a study that attempted to link grain boundary damage saturation behavior to variations in grain boundary mechanical properties was performed. This study found no direct relationships between grain boundary damage saturation behavior and variations in grain boundary properties. The results of this thesis provide researchers with several strategies for tuning the properties of amorphous-crystalline nanolaminates. These strategies include manipulated bulk attributes such as layer thickness and morphology as well as manipulation of microscale attributes such as grain boundary engineering. Finally, this thesis provides valuable insight into the damage loading/accommodation behavior of FCC symmetric tilt grain boundaries.

Download or read book Microstructural Stability of Nanostructured Fcc Metals During Cyclic Deformation and Fatigue written by Matthias Friedrich Funk and published by KIT Scientific Publishing. This book was released on 2014-05-22 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanostructured metals with maximal grain or twin sizes of less than 100 nm have advanced properties like increased strength.As beneficial as these microstructures can be for the strength of materials, they are not infinitely stable. During mechanical loading these metals tend to coarsen and lose their beneficial structure. Besides electron microscopic analysis of fatigued samples, in situ cycling tests were conducted in order to observe structural degradation during mechanical loading.

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.

Download or read book Deformation and Failure in Metallic Materials written by Kolumban Hutter and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 413 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is devoted to the deformation and failure in metallic materials, summarizing the results of a research programme financed by the "Deutsche Forschungsgemeinschaft". It presents the recent engineering as well as mathematical key aspects of this field for a broad community. Its main focus is on the constitutive behaviour as well as the damage and fracture of metallic materials, covering their mathematical foundation, modelling and numerics, but also relevant experiments and their verification.

Download or read book A Continuum Model of Deformation and Damage in Metals Coated with Nanolaminate Metallic Systems for Applications in High Energy Environments written by Mohammed Hamood Anazi and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research develops a continuum model of deformation and damage in metals coated with nanolaminate metallic systems (NMS) for potential applications in high-energy environments. The model is developed based on continuum mechanics within the elastic/viscoplastic framework that comprises constitutive equations which include dislocation density, size effect, strain hardening, strain rate effect, and damage. In addition, evolution laws for damage and dislocation density are considered. The model investigates the deformation behavior and strength in such materials and provides a predictive capability for designing engineering structures. The model is then implemented into a user subroutine in a commercial finite element analysis subroutine. Several numerical investigations are performed for steel and NMS at various individual layer thicknesses and compared with experimental data found in the literature. The deformation model developed for X70 steel and Copper/Niobium Cu/Nb NMS which is deformed variously based on its individual layer thickness. For X70, a modified Taylor equation is considered for hardening behavior, while for NMS, the confined layer slip (CLS) mechanism obeys a combined formula composed of Orwan's mechanism, interface stress, and dislocation density when the individual layer thickness is between 5 nm and 100 nm. Meanwhile, the nucleation (Nu) mechanism is controlled by the nucleation of a dislocation mechanism when the individual layer thickness is less than 5 nm. Next, the model is extended to consider softening or ductile failure based on an isotropic damage model that considers voids nucleation and growth. Finally, this research conducted an extensive numerical study on X70 and NMS. Then, X70 was coated with NMS to create a new composite called a X70 NMS composite. Likewise, the X70 NMS composite was studied based on a free damage state and damage state. A tension test according to ASTM standards was simulated to study the materials numerically. The models of the materials show good agreement with experimental results found in the literature, suggesting that the NMS coating is a good strength and ductility addition to X70 based on the X70 NMS composite study.

Download or read book Molecular Dynamics Simulation of Nanostructured Materials written by Snehanshu Pal and published by CRC Press. This book was released on 2020-05-15 with total page 305 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molecular dynamics simulation is a significant technique to gain insight into the mechanical behavior of nanostructured (NS) materials and associated underlying deformation mechanisms at the atomic scale. The purpose of this book is to detect and correlate critically current achievements and properly assess the state of the art in the mechanical behavior study of NS material in the perspective of the atomic scale simulation of the deformation process. More precisely, the book aims to provide representative examples of mechanical behavior studies carried out using molecular dynamics simulations, which provide contributory research findings toward progress in the field of NS material technology.

Download or read book The Nano Micro Interface 2 Volumes written by Marcel Van de Voorde and published by John Wiley & Sons. This book was released on 2015-03-09 with total page 771 pages. Available in PDF, EPUB and Kindle. Book excerpt: Controlling the properties of materials by modifying their composition and by manipulating the arrangement of atoms and molecules is a dream that can be achieved by nanotechnology. As one of the fastest developing and innovative -- as well as well-funded -- fields in science, nanotechnology has already significantly changed the research landscape in chemistry, materials science, and physics, with numerous applications in consumer products, such as sunscreens and water-repellent clothes. It is also thanks to this multidisciplinary field that flat panel displays, highly efficient solar cells, and new biological imaging techniques have become reality. This second, enlarged edition has been fully updated to address the rapid progress made within this field in recent years. Internationally recognized experts provide comprehensive, first-hand information, resulting in an overview of the entire nano-micro world. In so doing, they cover aspects of funding and commercialization, the manufacture and future applications of nanomaterials, the fundamentals of nanostructures leading to macroscale objects as well as the ongoing miniaturization toward the nanoscale domain. Along the way, the authors explain the effects occurring at the nanoscale and the nanotechnological characterization techniques. An additional topic on the role of nanotechnology in energy and mobility covers the challenge of developing materials and devices, such as electrodes and membrane materials for fuel cells and catalysts for sustainable transportation. Also new to this edition are the latest figures for funding, investments, and commercialization prospects, as well as recent research programs and organizations.

Download or read book The Nano Micro Interface written by Marcel Van de Voorde and published by John Wiley & Sons. This book was released on 2015-01-12 with total page 771 pages. Available in PDF, EPUB and Kindle. Book excerpt: Controlling the properties of materials by modifying their composition and by manipulating the arrangement of atoms and molecules is a dream that can be achieved by nanotechnology. As one of the fastest developing and innovative -- as well as well-funded -- fields in science, nanotechnology has already significantly changed the research landscape in chemistry, materials science, and physics, with numerous applications in consumer products, such as sunscreens and water-repellent clothes. It is also thanks to this multidisciplinary field that flat panel displays, highly efficient solar cells, and new biological imaging techniques have become reality. This second, enlarged edition has been fully updated to address the rapid progress made within this field in recent years. Internationally recognized experts provide comprehensive, first-hand information, resulting in an overview of the entire nano-micro world. In so doing, they cover aspects of funding and commercialization, the manufacture and future applications of nanomaterials, the fundamentals of nanostructures leading to macroscale objects as well as the ongoing miniaturization toward the nanoscale domain. Along the way, the authors explain the effects occurring at the nanoscale and the nanotechnological characterization techniques. An additional topic on the role of nanotechnology in energy and mobility covers the challenge of developing materials and devices, such as electrodes and membrane materials for fuel cells and catalysts for sustainable transportation. Also new to this edition are the latest figures for funding, investments, and commercialization prospects, as well as recent research programs and organizations.

Download or read book Nanomaterials by Severe Plastic Deformation written by Michael J. Zehetbauer and published by John Wiley & Sons. This book was released on 2006-03-06 with total page 872 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings of the "Second International Conference on Nanomaterials by Severe Plastic Deformation" review the enormous scientific avalanche that has been developing in the field over recent years. A valuable resource for any scientist and engineer working in this emerging field of nanotechnology.

Download or read book Defects and Deformation in Nanostructured Metals written by Christopher Earl Carlton and published by . This book was released on 2009 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: A better understanding of how the nanoscale environment affects the mechanical properties of materials, in particular metallic nanoparticles and nanocrystalline metals is vital to the development of next generation materials. Of special interest is obtaining a fundamental understanding of the inverse Hall-Petch Effect in nanocrystalline metals, and nanoindentation in individual nanoparticles. Understanding these subjects is critical to understanding how the mechanical properties of materials are fundamentally affected by nanoscale dimensions. These topics have been addressed by a combination of theoretical modeling and in-situ nanoindentation transmission electron microscopy (TEM) analysis. Specifically, the study of the inverse Hall-Petch effect in nanocrystalline metals will be investigated by a thorough review of the literature followed by a proposed novel theoretical model that better explains the experimentally observed behavior of nanocrystalline metals. On the other hand, the nanoindentation of individual nanoparticles is a very new research topic that has yet to aggregate a large body of experimental data. In this context, in-situ TEM nanoindentation experiments on silver nanoparticles will be first performed to determine the mechanisms of deformation in these nanostructures. A theoretical explanation for the observed deformation mechanisms will be then developed and its implications will be discussed. In addition to nanoparticles, this study will also provide unique and valuable insight into the deformation mechanisms of nanopillars, a growing area of research despite much controversy and speculation about their actual mechanisms of deformation. After studying the novel behavior of both nanocrystalline metals and nanoparticles, useful applications of both classes of materials will be explored. The discussion of applications will focus on utilizing the interesting behaviors explored in the dissertation. Of particular interest will be applications of nanoparticles and nanocrystalline materials to coatings, radiation resistance and super-plastic materials.

Download or read book Nanostructured Materials by High Pressure Severe Plastic Deformation written by Yuntian T. Zhu and published by Springer Science & Business Media. This book was released on 2006-01-20 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recently, it was reported that nanostructured materials processed under high pressure by HPT and ECAP have an extraordinary combination of both high strength and high ductility, which are two desirable, but rarely co-existing properties. These findings indicate that high-pressure is a critical factor that can be employed to process nanostructured materials with superior mechanical, and possibly also physical, properties. It is the objective of this workshop to review our current knowledge, identify issues for future research, and discuss future directions on the processing and properties of nanostructured materials via SPD techniques, with a special emphasis on high-pressure effects. The 42 peer-reviewed papers in this book cover areas of high pressure effect on the nanostructure and properties of SPD-processed materials, fundamentals of nanostructured materials, development of high-pressure SPD technologies for commercializations, recent advances of SPD technologies as well as applications and future markets of SPD-processed nanostructured materials.

Download or read book Trends in Nanoscale Mechanics written by Vasyl Michael Harik and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Damage Mechanisms in Nanolayered Metallic Composites written by and published by . This book was released on 2002 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The strengths of metallic multilayers, composed of alternating layers o f soft metals such as Cu and Nb, approach the theoretical limit of material strengih when the bilayer periods are on the order of a few nanometers. We have investigated the damage mechanisms in these ultra-high strength nanolayered composite inaterials subjected to monotonic deformation. Large strain plastic deformation such as rooin temperature rolling does not lead to any dislocation cell structure formation within the layers indicating that the deformation and dislocation storage mechanisms in nanostructured materials are completely different from the bulk. In bulk metals, dislocation pile-ups lead to heterogeneous slip, but in nano-materials, deformation by single disloqations on closely spaced glide planes results in more homogeneously distributed slip. The implications of the high tensile strengths and hoinogencous slip on the fatigue properties of nanolayered materials are also discussed.

Download or read book Understanding the Deformation Mechanisms in Nanostructured Metals by a Novel Discrete Crystal Plasticity Finite Element Model written by Rui Yuan and published by . This book was released on 2017 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Implementation of nanostructured metals and alloys for use in engineering applications requires a detailed knowledge of the underlying deformation mechanisms in these materials. It is well known that plastic deformation in metals and alloys is mainly mediated by dislocation activities. Nonetheless, TEM observations and atomistic simulations indicate that dislocation-mediated plasticity in nanostructured metals and alloys is significantly different from that in their coarse-grained counterparts. Therefore, this dissertation focuses on the exploration of the deformation mechanisms in nanostructured metals via crystal plasticity finite element modeling and simulation. A statistical grain boundary dislocation source model accounting for dislocation nucleation and slip events was developed and incorporated into a 3D discrete crystal plasticity finite element model to study the mechanical behaviors of nanostructured metals including nanocrystalline, nanotwinned and heterogeneous lamellar structured metals. It was found that a Hall-Petch scaling of strength emerged from grain size limitation on dislocation source length, and that the Hall-Petch slope depended sensitively on texture and was proportional to the Taylor factor. Furthermore, it was shown that experimentally observed scaling between yield strength and twin thickness in columnar-grained nanotwinned Cu arose from statistical variability in dislocation source length, and that reducing twin thickness could increase plastic anisotropy as a result of the increase in mean stress to emit dislocations. In addition, it was revealed that a heterogeneous lamellar structure consisting of a nanocrystalline layer sandwiched between two coarse-grained lamellae could effectively homogenize plastic strain in the nanocrystalline layer, leading to suppressed strain heterogeneity and enhanced ductility"--Abstract, page iv.

Download or read book Strength Deformation and Fracture in Metallic Nanostructures written by Xun Wendy Gu and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: