Download or read book Nanoscale Elastic plastic Transitions Mechanical Properties and Deformation Mechanisms of SiC Materials written by Ahmad Nawaz and published by . This book was released on 2017 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book SiC based Miniaturized Devices written by Stephen Edward Saddow and published by MDPI. This book was released on 2020-06-18 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: MEMS devices are found in many of today’s electronic devices and systems, from air-bag sensors in cars to smart phones, embedded systems, etc. Increasingly, the reduction in dimensions has led to nanometer-scale devices, called NEMS. The plethora of applications on the commercial market speaks for itself, and especially for the highly precise manufacturing of silicon-based MEMS and NEMS. While this is a tremendous achievement, silicon as a material has some drawbacks, mainly in the area of mechanical fatigue and thermal properties. Silicon carbide (SiC), a well-known wide-bandgap semiconductor whose adoption in commercial products is experiening exponential growth, especially in the power electronics arena. While SiC MEMS have been around for decades, in this Special Issue we seek to capture both an overview of the devices that have been demonstrated to date, as well as bring new technologies and progress in the MEMS processing area to the forefront. Thus, this Special Issue seeks to showcase research papers, short communications, and review articles that focus on: (1) novel designs, fabrication, control, and modeling of SiC MEMS and NEMS based on all kinds of actuation mechanisms; and (2) new developments in applying SiC MEMS and NEMS in consumer electronics, optical communications, industry, medicine, agriculture, space, and defense.

Download or read book Nanoscale Effects in the Tribological Properties of Materials a Molecular Dynamics Study written by and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the emergence of technological applications such as magnetic storage devices, MEMS applications and ultra-thin film coatings, the study of friction, adhesion, and wear has become increasingly important. For better design and durability of these nanoscale devices, it is essential to understand deformation in small volumes and in particular how deformation mechanisms can be related to frictional response of an interface in the regime where plasticity is fully developed. However, there is a lack of analytical models that relate tribological response to material properties and/or contact geometry for nanoscale elastic-plastic contacts. To provide these solutions, this thesis focuses on (a) development of analytical models that describe tribological behavior at nanoscale contacts and (b) investigation of atomistic mechanisms that control nanoscale deformation during sliding of elastic-plastic contacts. Large scale molecular dynamics studies of single asperity sliding have been conducted on three different materials: crystalline silicon carbide, crystalline copper and nanocrystalline silicon carbide. We demonstrate that, unlike in a number of other brittle materials, a high pressure phase transformation in SiC is highly unlikely under indentation or cutting conditions. The different categories of dislocation activity are investigated as a function of normal load and depth of cut for single crystal SiC. For nanocrystalline (nc) SiC, deformation is shown to occur via grain boundary sliding, heterogeneous nucleation of partial dislocations, formation of voids at the triple junctions, and grain pull-out. Our results demonstrate that machining of nc ceramics can be performed with nanometer-sized tools because in this regime brittle ceramics are pliable. In addition, we have developed a new analytical model which describes the plowing coefficient of friction during sliding of elastic-plastic contacts between a single asperity and a flat substrate. The proposed model includes the effects of both elastic recovery and pileup. Applicability of the new model is demonstrated on the examples of non-adhesive and adhesive contacts in SiC and Cu. In addition, our model shows excellent agreement with large scale molecular dynamics simulations and AFM experiments of nanoscratching on Cu single crystals.

Download or read book Nanoscale Surface and Interface Mechanics of Elastic Plastic Media with Smooth Patterned and Rough Surfaces written by Yin, Xi and published by . This book was released on 2011 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of this dissertation was to develop both finite element and analytical models of contact, friction, and wear phenomena encountered at the nanoscale. This was achieved by the development of continuum mechanics and discrete dislocation models of the deforming homogeneous or layered media and the use of self-affine (fractal) geometry for the representation of the interface topography. The specific accomplishments of this work are as follows. The contact problem of a rigid flat indenting an elastic-plastic semi-infinite medium with a sinusoidal surface profile was examined in light of a two-dimensional plane-strain finite element analysis. Numerical results of the dimensionless contact pressure, normal approach, average surface rise, center-line-average roughness, peak-to-valley roughness, cavity volume, and ratio of truncated-to-real contact area versus fractional contact area obtained for relatively compliant and stiff elastic-perfectly plastic half-spaces were compared with results obtained from a slip-line plasticity analysis. These results have direct application to metal working processes, such as rolling, and provide insight into the evolution of surface and subsurface contact deformation and asperity interaction of contacting surfaces exhibiting periodic waviness. Mechanical failure of patterned alternating phase-shift mask (APSM) nanostructures due to dynamic pressure loadings caused by megasonic cleaning was examined in the context of simulation results obtained from a two-dimensional plane-strain finite element analysis. A parametric study of the effects of microstructure geometry and loading frequency on the subsurface stress state and mask structural integrity was performed for two typical chromium-quartz APSM patterns. Numerical results elucidate possible failure modes and effect of microstructure dimensions on pattern damage during megasonic cleaning, and have direct implications to the design of extreme ultraviolet lithography masks and optimization of the megasonic cleaning process. Analytical models were developed to study the friction, wear, energy dissipation, and plastic flow of surfaces exhibiting multi-scale roughness in both sliding and normal contacts. A contact mechanics study of friction, energy dissipation, and abrasive wear of a hard and rough (fractal) surface sliding against a soft and smooth substrate was developed based on the slip-line theory of plasticity. The slip-line model yields relationships of the deformation behavior and coefficient of friction of a fully plastic asperity microcontact in terms of the applied normal load and interfacial adhesion. The analysis of the rough surface contact provides insight into the dependence of global friction coefficient, energy dissipated during sliding contact, and abrasive wear rate and wear coefficient on the global interference (total normal load effect), interfacial friction conditions (adhesion effect), fractal parameters (roughness effect), and elastic-plastic material properties (deformation mode effect). Numerical results for representative contact systems illustrate the effects of interfacial adhesion, global interference (total normal load), topography parameters, and material properties on friction coefficient, dissipated frictional energy, and wear rate/coefficient. The dependence of plastic deformation at asperity contacts and wear rate (coefficient) on global interference (total normal load), elastic-plastic material properties, topography (roughness), and work of adhesion of contacting surfaces was examined in a contact mechanics analysis of adhesive wear of rough (fractal) surfaces in normal contact. Loss of materials (wear) was presumed to originate from plastic contacting asperities, accounting for the contribution of interfacial adhesion to the normal load at each asperity microcontact. The effects of material properties, roughness, surface compatibility, and environmental conditions on the adhesive wear rate and wear coefficient were discussed in the context of numerical results for representative contact systems. Plane-strain indentation of a single-crystal semi-infinite medium by a rigid indenter was analyzed by discrete dislocation plasticity. The profile of the rigid indenter was characterized by either a smooth (cylindrical) or a rough (fractal) surface. This is the first contact analysis based on discrete dislocations derived for crystalline materials indented by a surface exhibiting multi-scale roughness. Short-range dislocation interactions were modeled in accord to dislocation constitutive rules, while long-range dislocation interactions were modeled by the elastic stress fields of edge dislocations. Simulation results provided insight into the effects of contact load, dislocation source and obstacle densities, slip-plane orientation and distribution, indenter radius, topography (roughness) of fractal surface, and multi-scale asperity interactions on damage at the onset of yielding (emission of first dislocation dipole) and plasticity evolution represented by the development of dislocation structures. Plastic deformation under the theoretical strength of the material was related to contact size effects. The findings in this dissertation provide fundamental understanding of surface deformation behavior, evolution of subsurface stress field due to contact traction, and tribological characteristics of elastic-plastic media with patterned and rough surface profiles subject to contact and/or surface loadings. The obtained results have direct implications in various industry fields, such as metal working, semiconductor electronics packaging, magnetic storage recording, and microelectromechanical devices.

Download or read book Structure and Mechanical Properties of Transition Group Metals Alloys and Intermetallic Compounds written by Tomasz Czujko and published by MDPI. This book was released on 2019-07-11 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of this Special Issue is to present the latest theoretical and experimental achievements concerning the mechanisms of microstructural change in metallic materials subject to different processing methods, and their effect on mechanical properties. It is my pleasure to present a series of compelling scientific papers written by scientists from the community of transition group metals, alloys, and intermetallic compounds.

Download or read book Plastic Deformation of Nanostructured Materials written by A. M. Glezer and published by CRC Press. This book was released on 2020-06-30 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plastic Deformation of Nanostructured Materials offers comprehensive analysis on the most important data and results in the field of materials strength and mechanics. This reference systematically examines the special features of the mechanical behavior and corresponding structural mechanisms of crystal structure defects with grain sizes that range from meso- to micro- levels. The book is organized into six chapters. Each chapter gives special attention to various topics including a detailed analysis of the main components of the dislocation structure, the conditions of transition from dislocation slip to grain boundary sliding as well as present studies concerned with the nature of severe plastic deformation processes. An indispensable reference for scientists, engineers, postgraduate students and others working in the physics of strength and development of highly efficient constructional multifunctional materials, Plastic Deformation of Nanostructured Materials highlights current interests on the structural mechanisms of plastic deformation of ultrafine-grained and nanostructured materials. Book jacket.

Download or read book In situ Materials Characterization written by Alexander Ziegler and published by Springer Science & Business Media. This book was released on 2014-04-01 with total page 265 pages. Available in PDF, EPUB and Kindle. Book excerpt: The behavior of nanoscale materials can change rapidly with time either because the environment changes rapidly or because the influence of the environment propagates quickly across the intrinsically small dimensions of nanoscale materials. Extremely fast time resolution studies using X-rays, electrons and neutrons are of very high interest to many researchers and is a fast-evolving and interesting field for the study of dynamic processes. Therefore, in situ structural characterization and measurements of structure-property relationships covering several decades of length and time scales (from atoms to millimeters and femtoseconds to hours) with high spatial and temporal resolutions are crucially important to understand the synthesis and behavior of multidimensional materials. The techniques described in this book will permit access to the real-time dynamics of materials, surface processes and chemical and biological reactions at various time scales. This book provides an interdisciplinary reference for research using in situ techniques to capture the real-time structural and property responses of materials to surrounding fields using electron, optical and x-ray microscopies (e.g. scanning, transmission and low-energy electron microscopy and scanning probe microscopy) or in the scattering realm with x-ray, neutron and electron diffraction.

Download or read book Thermo mechanical Behavior of Silicon at Nanoscale an in Situ Investigation written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Deformation Mechanisms Microstructure Evolution and Mechanical Properties of Nanoscale Materials Volume 1297 written by Julia R. Greer and published by Materials Research Society. This book was released on 2011-05-02 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Symposium P, "Deformation Mechanisms, Microstructure Evolution, and Mechanical Properties of Nanoscale Materials," was held Nov. 29-Dec. 3 at the 2010 MRS Fall Meeting in Boston, Massachusetts. This resultant volume addresses the topic of materials used in next-generation technological devices. These devices are used for a variety of applications-ranging from biomedical to space to energy-related-and will be subjected to non-ambient temperatures and high stresses and pressures. A variety of advanced nanomaterials and nanoscaled architectures have been proposed to meet these stringent demands. However, a complete understanding of the mechanisms that govern deformation at these scales is still elusive. This volume focuses on providing the state-of-the-art research on the mechanical response of nano- and microscale components that may comprise these devices and highlights emerging topics in novel mechanical testing techniques, in situ microscopy, high- and low-temperature deformation mechanisms, and mechanical property characterization of materials, as well as recent advances in atomistic and multiscale modeling of nanomaterials.

Download or read book Comprehensive Nanoscience and Nanotechnology written by and published by Academic Press. This book was released on 2019-01-02 with total page 1881 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive Nanoscience and Technology, Second Edition, Five Volume Set allows researchers to navigate a very diverse, interdisciplinary and rapidly-changing field with up-to-date, comprehensive and authoritative coverage of every aspect of modern nanoscience and nanotechnology. Presents new chapters on the latest developments in the field Covers topics not discussed to this degree of detail in other works, such as biological devices and applications of nanotechnology Compiled and written by top international authorities in the field

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 (

Download or read book Plasticity Failure and Fatigue in Structural Materials From Macro to Nano written by K. Jimmy Hsia and published by Wiley. This book was released on 2008-03-01 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains papers from the symposium held to honor Professor Hael Mughrabi, who devoted 40 years of research to the mechanical behavior of materials. In particular, Professor Mughrabi performed fundamental studies on the mechanisms of plastic deformation and fatigue based on dislocation mechanics. Readers of this book will find research development in deformation and fatigue including very high cycle fatigue of advanced engineering materials. Particular emphasis is given to mechanical properties of nanomaterials, and to the behavior and processes at the nanoscale in engineering materials. Specific subjects include deformation and fracture mechanisms; single crystals; mathematical modeling; cyclic, static and dynamic loading; and damage evolution.

Download or read book Plasticity for Engineers written by C. R. Calladine and published by ISBS. This book was released on 2000-09-15 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: Focusing on the plastic property of materials and the behavior of structures under load, this book presents perfect plasticity material as a model of irreversible mechanical behavior to analyze a range of continuum structural problems and metal-forming processes.

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 Plasticity Failure and Fatigue in Structural Materials from Macro to Nano written by Hsia and published by John Wiley & Sons. This book was released on 2012-11-01 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains papers from the symposium held to honor Professor Hael Mughrabi, who devoted 40 years of research to the mechanical behavior of materials. In particular, Professor Mughrabi performed fundamental studies on the mechanisms of plastic deformation and fatigue based on dislocation mechanics. Readers of this book will find research development in deformation and fatigue including very high cycle fatigue of advanced engineering materials. Particular emphasis is given to mechanical properties of nanomaterials, and to the behavior and processes at the nanoscale in engineering materials. Specific subjects include deformation and fracture mechanisms; single crystals; mathematical modeling; cyclic, static and dynamic loading; and damage evolution.

Download or read book Radiation Effects on Mechanical Properties of Thin 3c sic Investigated by in Situ Nanoindentation Via Transmission Electron Microscopy written by Xuying Liu (Ph.D.) and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In situ nanoindentation tests on thin 3C-SiC in a transmission electron microscope show small but non-negligible plastic deformation at room temperature. SiC is brittle in macroscopic studies but it can be become ductile when deformation occurs in small volumes. Here, we report such a brittle to ductile transition of 3C-SiC during nanoindentation of thin films (150-270 nm thick), and we reveal mechanisms of plastic deformation in situ. We find that plasticity in 3C-SiC is driven by dislocations, and that there is a pronounced plastic strain recovery at these length scales. We suggest that plastic deformation recovery arises from annihilation of transient dislocation extension driven by retracted external stress. In addition, we demonstrate that when the sample thickness is less than 90 nm, 3C-SiC becomes brittle again, and therefore the thickness of the films is important in determining whether the sample is brittle or ductile. In situ TEM nanoindentation tests on thin 3C-SiC irradiated at different radiation conditions indicate different mechanical behavior that is related to different microstructures. Samples irradiated at 600 [degrees]C 0.3 dpa and 600 2̐ʻC 3 dpa are easier to fracture under applied force than as-synthesized 3C-SiC. Long, straight, and simple crack paths are characteristic features for 600 [degrees]C 3 dpa samples, which is an evidence of easier fracture than 600 [degrees]C 0.3 dpa. However, 900 [degrees]C 3 dpa samples do not exhibit noticeable brittleness. Instead, they exhibit plastic deformation under applied force, which is the same as as-synthesized samples. Based on the microstructure of the irradiated samples, increasing the density of black spot defects that form at 600 [degrees]C degrades resistance to cracking, but the change of defect type to dislocation loops at 900 [degrees]C restores the plastic behavior. The results from this study are not consistent with macroscale analysis of fracture and cracking in irradiated SiC, which suggest different behavior and the microscale in irradiated as well as unirradiated SiC. These results therefore provide useful insights into the microscale properties of 3C-SiC which are important to multiscale simulation of 3C-SiC to predict mechanical performance of microelectromechanical systems, coatings, and next-generation fission reactor fuels.

Download or read book Radiation Effects on Mechanical Properties of Thin 3c sic Investigated by in Situ Nanoindentation Via Transmission Electron Microscopy written by Xuying Liu (Ph.D.) and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In situ nanoindentation tests on thin 3C-SiC in a transmission electron microscope show small but non-negligible plastic deformation at room temperature. SiC is brittle in macroscopic studies but it can be become ductile when deformation occurs in small volumes. Here, we report such a brittle to ductile transition of 3C-SiC during nanoindentation of thin films (150-270 nm thick), and we reveal mechanisms of plastic deformation in situ. We find that plasticity in 3C-SiC is driven by dislocations, and that there is a pronounced plastic strain recovery at these length scales. We suggest that plastic deformation recovery arises from annihilation of transient dislocation extension driven by retracted external stress. In addition, we demonstrate that when the sample thickness is less than 90 nm, 3C-SiC becomes brittle again, and therefore the thickness of the films is important in determining whether the sample is brittle or ductile. In situ TEM nanoindentation tests on thin 3C-SiC irradiated at different radiation conditions indicate different mechanical behavior that is related to different microstructures. Samples irradiated at 600 [degrees]C 0.3 dpa and 600 2̐ʻC 3 dpa are easier to fracture under applied force than as-synthesized 3C-SiC. Long, straight, and simple crack paths are characteristic features for 600 [degrees]C 3 dpa samples, which is an evidence of easier fracture than 600 [degrees]C 0.3 dpa. However, 900 [degrees]C 3 dpa samples do not exhibit noticeable brittleness. Instead, they exhibit plastic deformation under applied force, which is the same as as-synthesized samples. Based on the microstructure of the irradiated samples, increasing the density of black spot defects that form at 600 [degrees]C degrades resistance to cracking, but the change of defect type to dislocation loops at 900 [degrees]C restores the plastic behavior. The results from this study are not consistent with macroscale analysis of fracture and cracking in irradiated SiC, which suggest different behavior and the microscale in irradiated as well as unirradiated SiC. These results therefore provide useful insights into the microscale properties of 3C-SiC which are important to multiscale simulation of 3C-SiC to predict mechanical performance of microelectromechanical systems, coatings, and next-generation fission reactor fuels.