Download or read book Heterogeneities in Metallic Glasses Atomistic Computer Simulations on the Structure and Mechanical Properties of Copper zirconium Alloys and Composites written by Tobias Brink and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Atomistic Investigation of the Structural Transport and Mechanical Properties of Cu Zr Metallic Glasses written by Mohit Kumar and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The unique set of mechanical and magnetic properties possessed by metallic glasses has attracted a lot of recent scientific and technological interest. The development of new metallic glass alloys with improved manufacturability, enhanced properties and higher ductility relies on the fundamental understanding of the interconnections between their atomic structure, glass forming ability (GFA), transport properties, and elastic and plastic deformation mechanisms. This thesis is focused on finding these atomic structure-property relationships in Cu-Zr BMGs using molecular dynamics simulations. In the first study described herein, molecular dynamics simulations of the rapid solidification process over the Cu-Zr compositional domain were conducted to explore inter-dependencies of atomic transport and fragility, elasticity and structural ordering, and GFA. The second study investigated the atomic origins of serration events, which is the characteristic plastic deformation behaviour in BMGs. The combined results of this work suggest that GFA and ductility of metallic glasses could be compositionally tuned.
Download or read book Atomistic Simulations of Glasses written by Jincheng Du and published by John Wiley & Sons. This book was released on 2022-04-05 with total page 564 pages. Available in PDF, EPUB and Kindle. Book excerpt: A complete reference to computer simulations of inorganic glass materials In Atomistic Simulations of Glasses: Fundamentals and Applications, a team of distinguished researchers and active practitioners delivers a comprehensive review of the fundamentals and practical applications of atomistic simulations of inorganic glasses. The book offers concise discussions of classical, first principles, Monte Carlo, and other simulation methods, together with structural analysis techniques and property calculation methods for the models of glass generated from these atomistic simulations, before moving on to practical examples of the application of atomistic simulations in the research of several glass systems. The authors describe simulations of silica, silicate, aluminosilicate, borosilicate, phosphate, halide and oxyhalide glasses with up-to-date information and explore the challenges faced by researchers when dealing with these systems. Both classical and ab initio methods are examined and comparison with experimental structural and property data provided. Simulations of glass surfaces and surface-water reactions are also covered. Atomistic Simulations of Glasses includes multiple case studies and addresses a variety of applications of simulation, from elucidating the structure and properties of glasses for optical, electronic, architecture applications to high technology fields such as flat panel displays, nuclear waste disposal, and biomedicine. The book also includes: A thorough introduction to the fundamentals of atomistic simulations, including classical, ab initio, Reverse Monte Carlo simulation and topological constraint theory methods Important ingredients for simulations such as interatomic potential development, structural analysis methods, and property calculations are covered Comprehensive explorations of the applications of atomistic simulations in glass research, including the history of atomistic simulations of glasses Practical discussions of rare earth and transition metal-containing glasses, as well as halide and oxyhalide glasses In-depth examinations of glass surfaces and silicate glass-water interactions Perfect for glass, ceramic, and materials scientists and engineers, as well as physical, inorganic, and computational chemists, Atomistic Simulations of Glasses: Fundamentals and Applications is also an ideal resource for condensed matter and solid-state physicists, mechanical and civil engineers, and those working with bioactive glasses. Graduate students, postdocs, senior undergraduate students, and others who intend to enter the field of simulations of glasses would also find the book highly valuable.
Download or read book Metals Abstracts written by and published by . This book was released on 1993 with total page 1220 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Metallic Glasses written by Hu Huang and published by BoD – Books on Demand. This book was released on 2018-09-19 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metallic glasses are very promising engineering and functional materials due to their unique mechanical, chemical, and physical properties, attracting increasing attention from both scientific and industrial communities. However, their practical applications are greatly hindered due to three main problems: dimensional limit, poor tension plasticity, and difficulty in machining and shaping. Therefore, further investigation of these issues is urgently required. This book provides readers with recent achievements and developments in the properties and processing of metallic glasses, including mainly thermoplastic forming of metallic glasses (Chapter 2), atomic-level simulation of mechanical deformation of metallic glasses (Chapter 3), metallic glass matrix composites (Chapter 4), and tribo-electrochemical applications of metallic glasses (Chapters 5 and 6).
Download or read book Metallic Glasses and Their Composites written by D.V. Louzguine and published by Materials Research Forum LLC. This book was released on 2018-01-02 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: The formation of metallic glasses and dual-phase composite/hybrid materials is reviewed, as well as the glass transition process and the resulting structural phenomena. These materials exhibit high strength, extreme hardness, good wear resistance and large elastic deformation. Due to their excellent structural, functional, magnetic, chemical and biological properties metallic glasses are suitable for a great many applications, including in such areas as microelectromechanical devices, pressure sensors, orthopaedic screws and precision surgical instruments. Metallic Glasses, Metallic Glass Composites, Crystal/Glass Transition, Nano-Crystallization, Phase Separations, Supercooled Liquids, Glassy Nanocomposites, Nanoscale Quasicrystals, Mechanical Properties, Nanoscale Wear Resistance, Bauschinger Effect, Cryogenic Temperature, Porous Glasses, Nanocomposite Alloys, Soft Magnetic Alloys, Hard Magnetic Alloys, Magnetocaloric Effect, Corrosion Resistant Alloys, Surface Oxides, Catalysts
Download or read book Metallic Glasses written by Behrooz Movahedi and published by BoD – Books on Demand. This book was released on 2016-08-17 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metallic glasses and amorphous materials have attracted much more attention in the last two decades. A noncrystalline solid produced by continuous cooling from the liquid state is known as a glass. From the other point of view, a noncrystalline material, obtained by any other process, for example, vapor deposition or solid-state processing methods such as mechanical alloying, but not directly from the liquid state, is referred to as an amorphous material. At this moment, bulk metallic glasses (BMG) are appearing as a new class of metallic materials with unique physical and mechanical properties for structural and functional usage. Extreme values of strength, fracture toughness, magnetic properties, corrosion resistance, and other properties have been registered in BMG materials.
Download or read book Recent Advancements in Metallic Glasses written by Vitaly A. Khonik and published by MDPI. This book was released on 2021-06-09 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Special Issue “Recent Advancements in Metallic Glasses” presents ten original papers, considering both scientific and application issues related to metallic glasses. The papers are devoted to general consideration of the formation and defects of the glassy structure, defect evolution due to heat treatment, deformation behavior upon compression and high-pressure torsion, amorphous-crystalline transformation, hydrogenation behavior, and biomedical applications.
Download or read book Bulk Metallic Glasses written by C. Suryanarayana and published by CRC Press. This book was released on 2010-08-24 with total page 547 pages. Available in PDF, EPUB and Kindle. Book excerpt: In spite of the large amount of research activity in this subfield of materials science and engineering, there is no single book available that provides background information, methods of synthesis, characterization procedures, properties, and potential and existing applications.of bulk metallic glasses. Written in an easy-to-understand style by pioneering researchers in this field, Bulk Metallic Glasses is one of the first books to coherently discuss the synthesis, processing, properties, and applications of these unique materials. The book explores the differences between nanocrystalline, glassy, and amorphous solids as well as the thermodynamics and kinetics and various processing methods of glass formation. It critically compares the different criteria for glass formation, describes the advantages and limitations of experimental methods for synthesizing bulk metallic glasses in assorted sizes and shapes, and examines the kinetics of crystallization/devitrification and the mechanisms of transformations. It also covers the density, diffusivity, thermal expansion, electrical resistivity, specific heat, viscosity, corrosion resistance, mechanical behavior, and magnetic properties of bulk metallic glasses. After presenting a wide array of applications, the book concludes with a discussion on the future of these materials. The adoption of bulk metallic glasses into existing systems is besieged by many obstacles but due to their interesting combination of properties, future applications may be unlimited. A one-stop resource on all aspects of bulk metallic glasses, this book demonstrates the immense potential of these novel materials. It clearly elucidates the background, detailed methods of synthesis and characterization, structure, and properties of bulk metallic glasses.
Download or read book Mechanical Properties and Deformation Behaviors of Metallic Glasses Investigated by Atomic Level Simulations written by Hongwei Zhao and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The chapter reviewed recent developments about intrinsic structure of metallic glasses and their mechanical properties at atomic level, with an emphasis on making connections between developments in theory and simulations. Topics covered the following: structure analysis on metallic glasses with methods of pair distribution function, Honeycutt-Andersen analysis, and Voronoi tessellation; the connection of structure with the mechanical properties; shear band initiation and the development at the atomic level; and deformation mode transition from cast metallic glasses to reconstructed nanoglasses. These works provided theoretical understanding on the essence of metallic glasses' mechanical properties and deformation behaviors, and offered promises for more extensive applications of metallic glasses.
Download or read book Metallic Glasses Quasicrystals and Their Nanocomposites written by Devinder Singh and published by LAP Lambert Academic Publishing. This book was released on 2014-11-03 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: The endeavours made in this book are intended to study the effect of material tailoring on the crystallization behaviour, glass forming ability and structure/microstructure of Zr/Cu-based metallic glasses and nanoquasicrystal-glass composites. The substitution of Ga on Al site in Zr-Al-Cu-Ni alloy affects the nucleation and growth characteristics of quasicrystals and consequently changes the morphology of nanoquasicrystals. A new metallic glass composition; Zr-Ga-Cu-Ni with glass transition temperature (Tg); 614 K has been observed. The addition of Ti destabilizes the glassy phase in (Zr-Al-Cu-Ni)Ti alloys. Formation of single quasicrystalline phase by annealing the glass has been found for the alloys. The size of quasicrystal grain decreases with increase of Ti. Rapidly solidified ribbons of Cu-Ga-Mg-Ti and Cu-Al-Mg-Ti alloys show the formation of -brass type phase, which is an approximant of quasicrystals. The Cu-Ga-Mg-Ti alloy display ordered -brass structure, whereas Cu-Al-Mg-Ti leads to the formation of amorphous and nanocrystalline disordered bcc -brass phase. Electron diffraction patterns have been found to show a close structural similarity with the icosahedral phase.
Download or read book Plasticity Improvement of Metallic Glasses by Introducing Structural Heterogeneities written by Lei Zhao and published by . This book was released on 2019 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On the Correlation Between Microscopic Structural Heterogeneity and Embrittlement Behavior in Metallic Glasses written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: To establish a relationship between microstructure and mechanical properties, we systematically annealed a Zr-based bulk metallic glass (BMG) at 100 ~ 300°C and measured their mechanical and thermal properties. The as-cast BMG exhibits some ductility, while the increase of annealing temperature and time leads to the transition to a brittle behavior that can reach nearly-zero fracture energy. The differential scanning calorimetry did not find any significant changes in crystallization temperature and enthalpy, indicating that the materials still remained fully amorphous. Elastic constants measured by ultrasonic technique vary only slightly with respect to annealing temperature and time, which does obey the empirical relationship between Poisson's ratio and fracture behavior. Nanoindentation pop-in tests were conducted, from which the pop-in strength mapping provides a "mechanical probe" of the microscopic structural heterogeneities in these metallic glasses. Based on stochastically statistic defect model, we found that the defect density decreases with increasing annealing temperature and annealing time and is exponentially related to the fracture energy. A ductile-versus-brittle behavior (DBB) model based on the structural heterogeneity is developed to identify the physical origins of the embrittlement behavior through the interactions between these defects and crack tip.
Download or read book Experimental and Computational Investigations of Strain Localization in Metallic Glasses written by Ashwini Bharathula and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Metallic glasses are metallic alloy systems with disordered atomic structure. Due to their unique amorphous structure, they exhibit an extraordinary set of properties that are ideal for a wide variety of applications ranging from electrical transformers, armor-piercing projectiles, sporting goods and fuel cells to precision gears for micromotors. In particular, owing to their exceptional mechanical properties like near-theoretical strength (1-3 GPa), large elastic strain range (2-3%), and unusual formability above the glass transition temperature, metallic glasses have tremendous potential in structural applications. Unfortunately, their unique structure also gives rise to significant limitations, such as limited ductility at room temperature due to rapid localization of plastic flow in shear bands. However, when the test volumes approach the size of a shear band nucleus (~50-500 nm), it is believed that shear band formation and propagation can be constrained, leading to enhanced plasticity and failure strength. This study investigates the phenomenon of strain localization using both experimental and computational techniques. On the experimental front, sample size effects on strength, plasticity and deformation modes were explored in a Zr-based bulk metallic glass via micron- and sub-micron scale compression testing. Specimens with diameters ranging from 200 nm to a few microns were fabricated using Focused Ion Beam technique and were tested under uniaxial compression in a nanoindentation set-up with a flat punch tip. Effect of extrinsic factors like specimen geometry and machine stiffness on deformation behavior was discussed. Shear banding was shown to be more stable at this length scale than in macro-scale testing because of a smaller specimen to load frame stiffness ratio. It was found that as the specimen size is reduced to below 300 nm, the deformation mode changes from being discrete and inhomogeneous to more continuous flow including both localized and non-localized contributions at low strains. Moreover, the magnitude of strain bursts was found to decrease with decrease in specimen size. Furthermore, Weibull statistical analysis was performed to investigate the effect of specimen size on yield strength in this metallic glass. It was revealed that the dispersion in strengths increases dramatically with decrease in sample size, attributed to the size distribution of the defects responsible for shear banding. The findings are crucial in designing systems which promote plasticity in metallic glasses by suppressing the shear-band instability and also in direct application of these materials for structural purposes as small components in micro- and nano-scale systems. On the computational front, Molecular Dynamics (MD) simulations have been employed to generate Zr-Cu metallic glass structures. In order to analyze and better understand and visualize the concepts of "free" volume and flow defects in metallic glasses, an electron density model was developed as an upgrade to the traditional hard sphere approaches. Simple tension and shear modes of deformation were simulated using MD in Zr-Cu system, and role of open volume in deformation was studied using the electron density model. In uniaxial tension simulations, effect of temperature and deformation rate is examined, and the process of accumulation of free volume to the point of catastrophic failure is visualized using the Electron Density model. In shear simulations, we find that the as-quenched glass structures undergo homogeneous deformation and do not exhibit any strain localization. However, it is found that by incorporating a cylindrical void in the glass structure as a source of "free" volume, it is possible to induce strain localization. It was found that a critical void diameter of 8 Angstroms was required to successfully initialize strain localization in this system.
Download or read book Plastic Deformation in Zirconium Based Metallic Glasses Via Nanoindentation written by Zenon Humberto Melgarejo-Pinto and published by . This book was released on 2016 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the discovery in 1960 of Au-Si amorphous alloy by rapidly quenching with cooling rates up to 106 K/s metallic glasses became as an important research topic in the materials science community because of their intriguing processing routes, structure and properties. Recently, new multicomponent glassy- alloy systems, bulk metallic glasses (BMGs), appeared with lower critical cooling rates (103 to 1 K/s) and superlative properties, such as corrosion resistance, biocompatibility, and high strength/modulus ratio. Nevertheless, low temperature brittleness remains a concern. This brittleness comes from the tendency of plastic deformation to concentrate into extremely narrow shear bands. The present research pursues a better understanding of plastic deformation in metallic glasses (MGs) by studying, via nanoindentation, the effect of thermal history, composition, and loading paths on the mechanical behavior of Zr-based MGs. Differential scanning calorimeter (DSC) analysis helps to assess structural relaxation near glass transition temperature (Tg). Broadband nanoindentation creep (BNC) and load transient nanoindentation experiments contribute to characterize the hardness-strain rate behavior and indentation size effects, respectively. As-cast Zr50Cu45Al5 (at. %) metallic glasses evidenced hardness-strain rate loading path dependence, which gradually disappears by effect of the annealing treatments. Back-stresses effect is theorized as the cause of load path dependence behavior. Relaxation effect at low and high strain rates in BNC traces and load ramps “overshoots” in transient experiments enabled to confirm structural changes during mechanical deformation, which is not considered by thermal activation models of deformation. Most of the Zr-based metallic glasses exhibited measurable overshoot indentation size effect. Nonetheless, creep fraction size effect was observed just in as-cast Zr50Cu45Al5 alloys. Rheological mechanical model helps to both characterize the parameters involved in the plastic deformation of Zr-based metallic glasses and understand the competence between structural changes and mechanical deformation. Finally, nanoindentation analysis showed a gradient in hardness and modulus of as-cast ribbons and ingots, where the side with fastest cooling has the highest properties. The direction of the gradient is opposite to what other researchers have observed.
Download or read book Mechanical Behavior of Zr Based Metallic Glasses and Their Nanocomposites written by Devinder Singh and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In the present chapter, results of our recent investigations on the role of gallium (Ga) on the aluminum (Al) site in Zr69.5Al7.5-xGaxCu12Ni11 metallic glass (MG) composition have been discussed. The material tailoring and cooling rate effects on the mechanical behavior of Zr-based metallic glasses and their nanocomposites have been studied. The substitution of Ga on the Al site in Zr-Al-Cu-Ni alloy affects the nucleation and growth characteristics of quasicrystals (QCs) and consequently changes the morphology of nanoquasicrystals. The Zr69.5Al7.5-xGaxCu12Ni11 system displayed metallic glass formation in the range of x = 0-7.5. In this process, we have come out with a new glass composition; Zr-Ga-Cu-Ni with glass transition temperature (Tg)-614 K. The effect of cooling rate on the glass forming ability (GFA) and mechanical properties for this new metallic glass composition has been discussed and compared with some other Zr-based metallic glasses. The various indentation parameters such as microhardness, yield strength, strain hardening constant, nature of shear band formation, and so on for the alloys have been analyzed. The study is focused on investigations of these materials to understand the structure (microstructure) property correlations.
Download or read book Metals Abstracts Index written by and published by . This book was released on 1995 with total page 1390 pages. Available in PDF, EPUB and Kindle. Book excerpt:
