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.

Metallic glasses, a class of metal alloys which lack a periodic crystal structure, exhibit exceptional property combinations not accessible by other classes of materials. In spite of promise for widespread application, metallic glasses are difficult to synthesize and understanding of their structure and behavior is limited compared to crystalline alloys. There is no predictive criterion for determining if a particular alloy is capable of forming glass. Numerous glass-forming alloys have been reported, spanning a wide range of possible properties largely through trial and error. Engineering of these materials is difficult, as the connection between atomic structure and macroscopic behavior is not sufficiently developed to exploit particular behaviors in any intentional capacity. Using Molecular Dynamics (MD) simulations, three metallic glass-forming systems, Al-La, Cu-Zr and Cu-Ti-Zr were investigated and compared with the intention of connecting structure to properties and illuminating differences in glass-forming behavior in different alloys. From these simulations a specific mechanism occurring in the liquid, the changing of nearest neighbor environments, was identified and correlated to liquid viscosity. The change in viscosity with temperature, called fragility, was connected to this atomic-scale behavior allowing glass formers and non-glass formers in the Al-La alloys system to be separated from each other. The structure of each glass is readily available from these simulations, and the changes to neighbor environments in Al-La and Cu-Zr alloys, were found to be very similar when comparing the smaller atom type (Al, Cu). Differences in system-wide behavior for Al-La and Cu-Zr can be described based upon the behavior of the larger atom type (La, Zr), where Zr causes a major change in behavior as the majority component not exhibited by even very La-rich alloys. This dissimilarity between La and Zr provides a plausible explanation for Cu-Zr’s superior glass-forming ability compared to Al-La. Experimental data indicated that Cu-Ti-Zr achieve maximum glass-forming ability near Cu51.7Zr36.7Ti11.6. The addition of Ti to the Cu-Zr binary system causes a decrease in nearest-neighbor-switching events and stabilizes structures formed in the liquid, rather than destroying them. Cu51.7Zr36.7Ti11.6 also divides two compositional regions of hardness dependence: above 37% Zr the hardness scales with the concentration of Cu, while below 37% Zr the hardness scales with the concentration of Ti. Based on concepts developed for Al-La and Cu-Zr it was revealed that removing Cu drastically reduced the number of efficiently-packed Cu-centered structures. Below 37% Zr this effect is compensated by an increase in other dense structures but above 37% the effect is both more potent and uncompensated. The loss of these structures is responsible for the changes in yield behavior, and has an effect on the GFA. Finally, extension of these simulations to additional systems requires new multi-component EAM potentials, an essential input for MD simulations. The Rapid Alloy Method for the Production of Accurate General Empirical Potentials (RAMPAGE) was developed to create new multi-component potentials from elemental potentials available in the literature. Using RAMPAGE, the characteristics identified in glass-forming systems can be investigated in other metallic systems.

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).

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.

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.

This book introduces the application of computational homology for structural analysis of metallic glasses. Metallic glasses, relatively new materials in the field of metals, are the next-generation structural and functional materials owing to their excellent properties. To understand their properties and to develop novel metallic glass materials, it is necessary to uncover their atomic structures which have no periodicity, unlike crystals. Although many experimental and simulation studies have been performed to reveal the structures, it is extremely difficult to perceive a relationship between structures and properties without an appropriate point of view, or language. The purpose here is to show how a new approach using computational homology gives a useful insight into the interpretation of atomic structures. It is noted that computational homology has rapidly developed and is now widely applied for various data analyses. The book begins with a brief basic survey of metallic glasses and computational homology, then goes on to the detailed procedures and interpretation of computational homology analysis for metallic glasses. Understandable and readable information for both materials scientists and mathematicians is also provided.