Download or read book Mechanical Properties and Radiation Tolerance of Metallic Multilayers written by Nan Li and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: High energy neutron and proton radiation can induce serious damage in structural metals, including void swelling and embrittlement. Hence the design of advanced metallic materials with significantly enhanced radiation tolerance is critical for the application of advanced nuclear energy systems. The goals of this dissertation are to examine the fundamental physical mechanisms that determine the responses of certain metallic multilayers, with ultra-high density interface structures, to plastic deformation and high fluence He ion irradiation conditions. This dissertation focuses on the investigation of mechanical and radiation responses of Al/Nb and Fe/W multilayers. Radiation induced microstructural evolution in Cu and Cu/Mo multilayer films are briefly investigated for comparisons. Al/Nb multilayer films were synthesized by magnetron sputtering at room temperature. The interface is of Kurdjumov-Sachs orientation relationship. In situ nanoindentation inside a transmission electron microscope (TEM) reveal that interfaces act as strong barriers for dislocation transmission and dislocations climb along the Al/Nb interfaces at a much higher velocity than in bulk. The evolution of microstructure and mechanical properties of Al/Nb multilayers has been investigated after helium ion irradiations: 100 keV He+ ions with a dose of 6x10^16/cm2. When layer thickness, h, is greater than 25 nm, hardness barely changes, whereas radiation hardening is more significant at smaller h. This study shows that miscible fcc/bcc interface with large positive heat of mixing is not stable during ion irradiation. In parallel we investigate sputtered Fe/W multilayers. Film hardness increases with decreasing h, and approaches a maximum of 12.5 GPa when h = 1 nm. After radiation, radiation hardening is observed in specimens when h>/= 5 nm, however, hardness barely changes in irradiated Fe/W 1 nm specimens due to intermixing. In comparison, Cu/Mo 5 nm multilayers with immiscible interface has also been investigated after helium ion irradiations. Interfaces exhibit significantly higher helium solubility than bulk. He/vacancy ratio affects the formation and distribution of He bubbles. The greater diameter of He bubbles in Cu than Mo originates from the ease of bubble growth in Cu via punching of interstitial loops. Finally, helium bubble migration and growth mechanisms were investigated in irradiated Cu (100) single crystal films via in situ heating inside a TEM. The activation energy for bubble growth is ~ 0.02 eV at low temperature. At higher temperatures, the activation energy for bubble coalescence is ~ 0.22 eV inside crystal, and 0.34 eV close to surface. The migration mechanisms of helium bubbles involve continuous as well as Brownian movement.

Download or read book Enhanced Radiation Tolerance in Sputtered Cu V Multilayers written by Engang Fu and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: High energy particle (neutron, proton and He ions) irradiation to materials typically leads to deteriorating properties, including void swelling, blistering, embrittlement, fracture and exfoliation of surfaces. This dissertation examines size dependent radiation damage in nanostructured metallic multilayers synthesized by the magnetron sputtering technique at room temperature. It reveals the roles of interface in achieving enhanced radiation tolerance in metallic materials. The microstructure and mechanical properties of as-deposited Cu/V multilayer films are systemically investigated, providing the basis for studying radiation damage mechanisms. Sputter-deposited Cu/V multilayers are subjected to helium (He) ion irradiation at room temperature with a peak dose of 6 displacements per atom (dpa). The average helium bubble density and lattice expansion induced by radiation decrease significantly with decreasing h, where h is individual layer thickness. The magnitude of radiation hardening decreases with decreasing h, and becomes negligible when h is 2.5 nm or less. The interactions between interfaces and radiation induced point defects and the evolution of microstructurs and mechanical behavior are discussed. This study indicates that nearly immiscible Cu/V interfaces spaced a few nm apart can effectively reduce the concentration of radiation induced point defects. Dose dependent radiation damage at room temperature in these Cu/V multilayers is systematically investigated with a peak dose in the range of 1-12 dpa. Peak bubble density increases with increasing dose, but it is much lower in Cu/V 2.5 nm multilayers than that in Cu/V 50 nm specimens. A similar radiation hardening trend is observed in multilayers irradiated at different fluences. Radiation hardening increases with dose and seems to reach saturation at a peak dose of 6 dpa. Negligible hardening for fine (h less than/equal to 2.5 nm) multilayers is observed at all dose levels. Thermal stability of Cu/V multilayers is revealed by in situ annealing inside a transmission electron microscope. During isothermal annealing at 600 degrees C grain boundary grooving occurs across layer interfaces in Cu/V 50 nm specimens, whereas Cu/V 5 nm multilayers appear rather stable. Annealing of Cu/V multilayers at 400 degrees C leads to hardening of multilayers, whereas softening occurs in Cu/V multilayers annealed at 600 degrees C. The evolution of mechanical properties during annealing is correlated to the degradation of the layer interface and the consequent reduction of interface resistance to the transmission of single dislocation.

Download or read book Principles of Extreme Mechanics XM in Design for Reliability DfR written by Arief Suriadi Budiman and published by Springer Nature. This book was released on 2021-11-13 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses issues pertinent to mechanics and stress generation, especially in recent advanced cases of technology developments, spanning from micrometer interconnects in solar photovoltaics (PV), next-gen energy storage devices to multilayers of nano-scale composites enabling novel stretchable/flexible conductor technologies. In these cases, the mechanics of materials have been pushed to the extreme edges of human knowledge to enable cutting-edge, unprecedented functionalities and technological innovations. Synchrotron X-ray diffraction, in situ small-scale mechanical testing combined with physics-based computational modeling/simulation, has been widely used approaches to probe these mechanics of the materials at their extreme limits due to their recently discovered distinct advantages. The techniques discussed in this manuscript are highlights specially curated from the broad body of work recently reported in the literature, especially ones that the author had led the pursuits at the frontier himself. Extreme stress generation in these advanced material leads to often new failure modes, and hence, the reliability of the final product is directly affected. From the recent topics and various advanced case studies covered in this book, the reader gets an updated knowledge of how new mechanics can and has been applied in Design-for-Reliability (DfR) for some of the latest technological innovations known in our modern world. Further, this also helps in building better designs, which may avoid the pitfalls of the current practiced trends.

Download or read book The Structural and Mechanical Properties of Metallic Multilayers written by John T. Hoekstra and published by . This book was released on 1995 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Radiation on Materials written by Arvind S. Kumar and published by ASTM International. This book was released on 1994 with total page 1319 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Radiation on Materials written by and published by ASTM International. This book was released on 1981 with total page 1227 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Materials Design for Advanced Nuclear Energy Systems written by Samuel W. McAlpine and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced nuclear reactors present a multitude of materials challenges due to high operating temperatures, corrosive environments, and neutron radiation damage. In this thesis, I focus on two approaches to designing better materials for advanced reactors, high entropy alloys (HEAs) and metallic multilayer composites (MMLCs). HEAs are chemically disordered solid solutions combining 4-5 or more elements, which of- ten have superior mechanical properties and radiation damage tolerance compared to advanced steels and Ni-base alloys. While HEAs have garnered immense attention within the research community, there is still no effective approach for predicting which compositions will tend to form a single phase microstructure. I develop an atomistic thermodynamic model which uses a quantity I coin as the atomistic mixing energy (AME) to understand phase stability in HEAs and predict which elements are more or less favored to mix within a given HEA system. The model also facilitates the correct calculation of the vacancy formation energy distribution in HEAs which gives insight to radiation damage, solid-state diffusion, and other vacancy-driven material behavior. To test the validity of the model, I synthesize and characterize 5 refractory HEA compositions: NbMoTaTiW, NbMoTaTiV, NbMoTaTiZr, NbMoTaHfW, and WTaVTiCr. Implications for single phase HEA design utilizing the model developed in this thesis are explored. The final part of the thesis focuses on MMLCs, in which different material functionalities are separated into different layers. Currently, few studies have aimed to understand radiation damage effects at the interface between different layers. I use interfacial self-ion irradiation along the bimetal interface within 2 MMLC systems to shed light on the radiation damage behavior of the interfacial region. Radiation--enhanced diffusion was observed in one MMLC, and a Cr-rich phase is observed along the interface in both MMLCs. The propensity for radiation-enhanced diffusion is related to the compositional gradient across the interface, while the Cr-rich interfacial phase could potentially lead to material embrittlement within MMLCs.

Download or read book Radiation Damage in Nanostructured Metallic Films written by Kaiyuan Yu and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: High energy neutron and charged particle radiation cause microstructural and mechanical degradation in structural metals and alloys, such as phase segregation, void swelling, embrittlement and creep. Radiation induced damages typically limit nuclear materials to a lifetime of about 40 years. Next generation nuclear reactors require materials that can sustain over 60 - 80 years. Therefore it is of great significance to explore new materials with better radiation resistance, to design metals with favorable microstructures and to investigate their response to radiation. The goals of this thesis are to study the radiation responses of several nanostructured metallic thin film systems, including Ag/Ni multilayers, nanotwinned Ag and nanocrystalline Fe. Such systems obtain high volume fraction of boundaries, which are considered sinks to radiation induced defects. From the viewpoint of nanomechanics, it is of interest to investigate the plastic deformation mechanisms of nanostructured films, which typically show strong size dependence. By controlling the feature size (layer thickness, twin spacing and grain size), it is applicable to picture a deformation mechanism map which also provides prerequisite information for subsequent radiation hardening study. And from the viewpoint of radiation effects, it is of interest to explore the fundamentals of radiation response, to examine the microstructural and mechanical variations of irradiated nanometals and to enrich the design database. More importantly, with the assistance of in situ techniques, it is appealing to examine the defect generation, evolution, annihilation, absorption and interaction with internal interfaces (layer interfaces, twin boundaries and grain boundaries). Moreover, well-designed nanostructures can also verify the speculation that radiation induced defect density and hardening show clear size dependence. The focus of this thesis lies in the radiation response of Ag/Ni multilayers and nanotwinned Ag subjected to charged particles. The radiation effects in irradiated nanograined Fe are also investigated for comparison. Radiation responses in these nanostructured metallic films suggest that immiscible incoherent Ag/Ni multilayers are more resistant to radiation in comparison to their monolithic counterparts. Their mechanical properties and radiation response show strong layer thickness dependence in terms of radiation hardening and defect density. Coherent twin boundaries can interact with stacking fault tetrahedral and remove them effectively. Twin boundaries can actively absorb radiation induced defects and defect clusters resulting in boundary migration. Size dependence is also found in nanograins where fewer defects exhibit in films with smaller grains. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/149359

Download or read book Molecular Dynamics Modeling of the Mechanical Behavior of Metallic Multilayers written by and published by . This book was released on 1993 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: Constant-stress molecular dynamics simulations are used to study the mechanical properties of equal concentration Cu-Ni (111) metallic multilayers of repeat lengths 0.4--0.5 nm. Uniaxial stress is applied along the close-packed and perpendicular to the close-packed directions within the (111) plane. The observed elastic moduli do not display a supermodulus effect as observed in experimental bulge tests for the biaxial modulus. However, both the average interlayer spacing and the out-of-plane Poisson ratio display anomalous effects for multilayer repeat lengths below about two nanometers.

Download or read book Effects of Radiation on Materials written by N. H. Packan and published by ASTM International. This book was released on 1990 with total page 679 pages. Available in PDF, EPUB and Kindle. Book excerpt: Annotation Effects of Radiation on Materials: Fourteenth International Symposium was presented at Andover, MA, June 1988. The symposium was sponsored by ASTM Committee E-10 on Nuclear Technology and Applications. The papers from the first three days of the symposium appear in the two volumes of this publication. Volume I encompasses radiation damage- induced microstructures; point defect, solute, and gas atom effects; atomic-level measurement techniques; and applications of theory. Volume II includes mechanical behavior, all papers dealing with pressure-vessel steels, breeder reactor components, dosimetry, and nuclear fuels. The fourth day of the symposium was devoted to the single topic of reduced-activation materials (see TK9204). The two volumes are separately sold at $127 and $128 respectively; each is independently indexed. Annotation copyrighted by Book News, Inc., Portland, OR.

Download or read book Bulk Metallic Glasses written by Michael Miller and published by Springer Science & Business Media. This book was released on 2007-09-26 with total page 243 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bulk metallic glasses are a new emerging field of materials with many desirable and unique properties. These amorphous materials have many diverse applications from structural applications to biomedical implants. This book provides a complete overview of bulk metallic glasses. It covers the principles of alloy design, glass formation, processing, atomistic modeling, computer simulations, mechanical properties and microstructures.

Download or read book Radiation Damage in Materials written by Yongqiang Wang and published by MDPI. This book was released on 2020-12-28 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: The complexity of radiation damage effects in materials that are used in various irradiation environments stems from the fundamental particle–solid interactions and the subsequent damage recovery dynamics after the collision cascades, which involves multiple length and time scales. Adding to this complexity are the transmuted impurities that are unavoidable from accompanying nuclear processes. Helium is one such impurity that plays an important and unique role in controlling the microstructure and properties of materials used in fast fission reactors, plasma-facing and structural materials in fusion devices, spallation neutron target designs, actinides, tritium-containing materials, and nuclear waste. Their ultra-low solubility in virtually all solids forces He atoms to self-precipitate into small bubbles that become nucleation sites for further void growth under radiation-induced vacancy supersaturations, resulting in material swelling and high-temperature He embrittlement, as well as surface blistering under low-energy and high-flux He bombardment. This Special Issue, “Radiation Damage in Materials—Helium Effects”, contains review articles and full-length papers on new irradiation material research activities and novel material ideas using experimental and/or modeling approaches. These studies elucidate the interactions of helium with various extreme environments and tailored nanostructures, as well as their impact on microstructural evolution and material properties.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Radiation on Materials written by H. R. Brager and published by ASTM International. This book was released on 1982 with total page 786 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanical Properties and Radiation Tolerance of Ultrafine Grained and Nanocrystalline Metals written by Cheng Sun and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Austenitic stainless steels are commonly used in nuclear reactors and have been considered as potential structural materials in fusion reactors due to their excellent corrosion resistance, good creep and fatigue resistance at elevated temperatures, but their relatively low yield strength and poor radiation tolerance hinder their applications in high dose radiation environments. High angle grain boundaries have long been postulated as sinks for radiation-induced defects, such as bubbles, voids, and dislocation loops. Here we provide experimental evidence that high angle grain boundaries can effectively remove radiation-induced defects. The equal channel angular pressing (ECAP) technique was used to produce ultrafine grained Fe-Cr-Ni alloy. Mechanical properties of the alloy were studied at elevated temperature by tensile tests and in situ neutron scattering measurements. Enhanced dynamic recovery process at elevated temperature due to dislocation climb lowers the strain hardening rate and ductility of ultrafine grained Fe-Cr-Ni alloy. Thermal stability of the ultrafine grained Fe-Cr-Ni alloy was examined by ex situ annealing and in situ heating within a transmission electron microscope. Abnormal grain growth at 827 K (600°C) is attributed to deformation-induced martensite, located at the triple junctions of grains. Helium ion irradiation studies on Fe-Cr-Ni alloy show that the density of He bubbles, dislocation loops, as well as irradiation hardening are reduced by grain refinement. In addition, we provide direct evidence, via in situ Kr ion irradiation within a transmission electron microscope, that high angle grain boundaries in nanocrystalline Ni can effectively absorb irradiation-induced dislocation loops and segments. The density and size of dislocation loops in irradiated nanocrystalline Ni were merely half of those in irradiated coarse grained Ni. The results imply that irradiation tolerance in bulk metals can be effectively enhanced by microstructure refinement. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/149516

Download or read book Study of Mechanical Behavior of Metal ceramic Al SiC Multilayers Using Finite Element Method written by Raghu Vardhan Narne and published by . This book was released on 2018 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: The increasing and never-ending demand for more optimal mechanical properties in a single material, emphasized and led to the on-going research in design and development of multilayered multimaterials. A set of different materials when layered one on another, exhibit many contrary properties making it practically functional in wide range of mechanical loadings and environments. These sets of different materials, so called composite laminates, consist alternating layers of two or more materials in different combinations like Metal -- Metal, Ceramic -- Ceramic, Ceramic -- Metal exhibiting outstanding mechanical properties like high strength, toughness, fatigue resistance etc. There is a great need to better understand the mechanical behavior of such multilayered multimaterials, which is costly, time consuming and highly error prone to analyze the mechanical properties using the traditional manual methods which use experimental setups. The use of modern finite element methods backed with the efficient computing power could cut the costs, work time and augment the efficiency. A ceramic/metal (CerMet) pillar of Aluminum -- Silicon Carbide is modeled with alternative layers of Al & SiC of identical thickness, using axi-symmetrical elements with the help of commercial FEA package ANSYS APDL. The cohesive zone model has been applied on the interfaces to capture the interface effect on the mechanical behavior of the samples. The model was validated using the available data in the literature for a uniform compression of the pillar using a flat punch. To further our understanding on the mechanical response of the samples under non-uniform loading, the samples were indented using a spherical punch. The effects of cracks in the interfaces between the layers and the ratio of metal/ceramic layer thickness, on the mechanical behavior of the nanolaminate, are investigated with the help of Load-Displacement curves.

Download or read book Advances in Thin Films Nanostructured Materials and Coatings written by Alexander D. Pogrebnjak and published by Springer. This book was released on 2019-02-08 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights the latest advances in chemical and physical methods for thin-film deposition and surface engineering, including ion- and plasma-assisted processes, focusing on explaining the synthesis/processing–structure–properties relationship for a variety of thin-film systems. It covers topics such as advances in thin-film synthesis; new thin-film materials: diamond-like films, granular alloys, high-entropy alloys, oxynitrides, and intermetallic compounds; ultra-hard, wear- and oxidation-resistant and multifunctional coatings; superconducting, magnetic, semiconducting, and dielectric films; electrochemical and electroless depositions; thin-film characterization and instrumentation; and industrial applications.