Mechanical Behaviour Of Nanostructured Materials

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.

The processing and mechanical behaviour of bulk nanostructured materials are one of the most interesting new fields of research on advanced materials systems. Many nanocrystalline materials possess very high strength with still good ductility, and exhibit high values of fatigue resistance and fracture toughness. There has been continuing interest in these nanomaterials for use in structural and biomedical applications, and this has led to a large number of research programs worldwide. This book focuses on the processing techniques, microstructures, mechanical and physical properties, and applications of bulk nanostructured materials, as well as related fundamental issues. Only since recently can such bulk nanostructured materials be produced in large bulk dimensions, which opens the door to their commercial applications.

Special topic volume with invited peer reviewed papers only

Nowadays, with the improved abilities of computers, molecular modeling has become a powerful technique in computational chemistry with ever-increasing practical interests. At the moment, using effective algorithms along with powerful processors enables us to simulate systems, including thousands of atoms up to several microseconds. However, finding a balance between the computational costs and reliable results still remains a challenge. Two general approaches help us to reveal the behavior of these systems: quantum chemical calculations and molecular mechanics calculations. Quantum mechanics deals with physical phenomena as well as atoms behavior during chemical bonding and falls in the category of modern physics. In this book, two of the most practical quantum mechanics approaches are investigated: density functional theory (DFT) and density-functional tight-binding (DFTB).

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.

This book highlights the mechanical properties of nanomaterials produced by several techniques for various applications. The dislocations observed in specimens obtained in nanomaterials are discussed on the chapter about deformation process. Partial dislocations and grain boundary sliding deformation phenomena in nanomaterial specimens are also deeply discussed. Tests for tension, compression, and hardness are described. The behavior of nanomaterials is compared to macrosize specimens, and the results obtained for different fabrication methods are also compared. The special characteristics of nanomaterials are summarized at the end of the book.

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.

Providing in-depth information on how to obtain high-performance materials by controlling their nanostructures, this ready reference covers both the bottom-up and the top-down approaches to the synthesis and processing of nanostructured materials. The focus is on advanced methods of mechanical nanostructuring such as severe plastic deformation, including high pressure torsion, equal channel angular processing, cyclic extrusion compression, accumulative roll bonding, and surface mechanical attrition treatment. As such, the contents are inherently application-oriented, with the methods presented able to be easily integrated into existing production processes. In addition, the structure-property relationships and ways of influencing the nanostructure in order to exhibit a desired functionality are reviewed in detail. The whole is rounded off by a look at future directions, followed by an overview of applications in various fields of structural and mechanical engineering. With its solutions for successful processing of complex-shaped workpieces and large-scale specimens with desired properties, this is an indispensable tool for purposeful materials design.