Using Molecular Dynamics Simulations To Quantify The Energy Stored In Irradiation Defects In Tungsten And Aluminum

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Using Molecular Dynamics Simulations to Quantify the Energy Stored in Irradiation Defects in Tungsten and Aluminum

Author : Sean Lowder
Publisher :
ISBN 13 :
Total Pages : 67 pages
Book Rating : 4.:/5 (11 download)

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Book Synopsis Using Molecular Dynamics Simulations to Quantify the Energy Stored in Irradiation Defects in Tungsten and Aluminum by : Sean Lowder

Download or read book Using Molecular Dynamics Simulations to Quantify the Energy Stored in Irradiation Defects in Tungsten and Aluminum written by Sean Lowder and published by . This book was released on 2017 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radiation damage in materials can create potentially catastrophic effects by causing failure in critical reactor components. In order to prevent such failures, it is imperative that this damage is understood and quantified. Currently, displacements-per-atom (DPA) is the most common form of expressing the amount of radiation a material has received. With its limitations on accurately expressing how much damage remains in a material post-irradiation, the DPA does not provide enough information about an exposed material to fully understand how it is has been compromised. One suggested replacement for the DPA is the Wigner stored energy, which is a measurement of the energy stored in radiation defects. To prepare for future experimental work, irradiation in tungsten and aluminum was simulated and analyzed for trends in defect energy. With increasing amounts of radiation exposure, it was found that the average energy associated with individual defects remains constant, but that defect clustering and dislocation forming increases. Simulations were then performed to mimic the process of calorimetry heating. These simulations showed how the defects annealed out with heating, and the results will be extrapolated to predict experimental results. If Wigner energy can be successfully measured and characterized, it can become a more universal and reliable way of expressing radiation damage, improving safety throughout the nuclear industry.

Quantifying Radiation Damage Through Stored Energy Released During Defect Annealing in Metals

Author : Charles Arthur Hirst
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (135 download)

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Book Synopsis Quantifying Radiation Damage Through Stored Energy Released During Defect Annealing in Metals by : Charles Arthur Hirst

Download or read book Quantifying Radiation Damage Through Stored Energy Released During Defect Annealing in Metals written by Charles Arthur Hirst and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: With full knowledge of a material's atomistic structure, it is possible to predict any macroscopic property of interest. In practice, this is hindered by limitations of the chosen characterisation technique. For example, transmission electron microscopy (TEM) is unable to detect the smallest and most numerous defects in irradiated metals. Instead of spatial characterisation, defects can be detected and quantified through their excess energy.

Numerical Simulations of Tungsten Under Helium Irradiation

Author : Thibault Faney
Publisher :
ISBN 13 :
Total Pages : 115 pages
Book Rating : 4.:/5 (18 download)

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Book Synopsis Numerical Simulations of Tungsten Under Helium Irradiation by : Thibault Faney

Download or read book Numerical Simulations of Tungsten Under Helium Irradiation written by Thibault Faney and published by . This book was released on 2013 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic confinement fusion is a promising technology for electricity production due to available fuel and low waste products. However, the construction of a nuclear fusion reactor remains a scientific challenge. One of the main issues is the resistance of the plasma facing materials exposed to very harsh operating conditions. Tungsten is the leading candidate for the divertor, a crucial plasma facing component. This dissertation focuses on modeling the behavior of tungsten under irradiation conditions relevant to the divertor operations using a multi-scale modeling approach. In particular, high fluxes of helium ions at low energy impact the divertor and are responsible for changes in the tungsten microstructure such as the formation of helium blisters and ''fuzz"--Like structures which can ultimately lead to erosion, degradation of materials performance and materials failure. A spatially dependent cluster dynamics model is introduced in order to model the evolution of the tungsten microstructure under irradiation. This continuum model is based on kinetic rate theory and handles each material defect type independently. Under the assumptions of a low dilute limit and no spatial correlation between defects, this leads to a large system of non-linear reaction-diffusion equations. Hence, the results addressed in this thesis consist in the determination of the kinetic parameters for the cluster dynamics model, the construction of a solver which efficiently deals with the large non-linear system of partial differential equations, the determination of the applicability of the model to fusion relevant conditions, and the model results for a variety of irradiation conditions. The input kinetic parameters to the cluster dynamics model are the defects' diffusion coefficients, binding energies and capture radii. These can be determined using a molecular dynamics and density functional theory simulations as well as empirical data. The challenge lies in obtaining a consistent set of kinetic parameters. Therefore, a method to determine the value of the diffusion coefficients for small helium, interstitial and vacancy defects at various temperatures using only molecular dynamics simulations is presented. Binding energies are also determined using molecular dynamics, and when combined with the diffusion coefficients they form a consistent set of kinetic parameters. An efficient implementation of a parallel solver is presented to deal with the large number of stiff non linear reaction diffusion equations. The implementation of a SDIRK scheme using a modified version of the SPIKE algorithm gives excellent parallelization results and suggests that this implementation would also be efficient for an extension of the model to two or three dimensions. Convergence results for a variety of SDIRK schemes show a convergence order reduction of the numerical scheme due to the stiffness of the reaction and diffusion terms. A comparison between simulation results using the cluster dynamics model and experimental results is essential to assess the validity of the model. Comparison with thermal helium desorption spectrometry experiments at low flux and fluence shows an excellent agreement between simulation and experiments and indicate that the model captures the key physical properties affecting the evolution of the tungsten microstructure. Further comparison with molecular dynamics simulations at extremely high fluxes provides an insight in the expected limitations of the model due to surface effects and dilute limit approximations breakdown when applied to fusion relevant conditions. Results of the model under fusion relevant conditions show the formation of large helium bubbles under the surface at a temperature dependent depth. The results are very sensitive to both irradiation flux and temperature. At large temperatures, a small concentration of large bubbles forms first deep under the tungsten surface, and forms a ``plug" which moves towards the surface until eventually the dilute limit approximation breaks down, indicating that the sub-surfaces bubbles become interlinked. At small temperatures, a larger concentration of smaller bubbles forms close to the surface until eventually surface effects such as bubble bursting are expected to occur. These results are found to be in good agreement with a similar analytical reaction diffusion model for fusion relevant conditions. More work is needed to simulate past the dilute limit breakdown and examine the possibility of taking into account surface effects.

Energy Dependence of Electron-induced Radiation Damage in Tungsten

Author : James A. DiCarlo
Publisher :
ISBN 13 :
Total Pages : 34 pages
Book Rating : 4.:/5 (31 download)

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Book Synopsis Energy Dependence of Electron-induced Radiation Damage in Tungsten by : James A. DiCarlo

Download or read book Energy Dependence of Electron-induced Radiation Damage in Tungsten written by James A. DiCarlo and published by . This book was released on 1971 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electron irradiation energy thresholds for producing damage in polycrystalline tungsten wire.

Electronic Effects in High-energy Radiation Damage in Tungsten

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (957 download)

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Book Synopsis Electronic Effects in High-energy Radiation Damage in Tungsten by :

Download or read book Electronic Effects in High-energy Radiation Damage in Tungsten written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Even though the effects of the electronic excitations during high-energy radiation damage processes are not currently understood, it is shown that their role in the interaction of radiation with matter is important. We perform molecular dynamics simulations of high-energy collision cascades in bcc-tungsten using the coupled two-temperature molecular dynamics (2T-MD) model that incorporates both the effects of electronic stopping and electron-phonon interaction. We compare the combination of these effects on the induced damage with only the effect of electronic stopping, and conclude in several novel insights. In the 2T-MD model, the electron-phonon coupling results in less damage production in the molten region and in faster relaxation of the damage at short times. We show these two effects lead to a significantly smaller amount of the final damage at longer times.

Point Defect Calculations in Tungsten

Author : Ronald L. Danilowicz
Publisher :
ISBN 13 :
Total Pages : 18 pages
Book Rating : 4.:/5 (31 download)

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Book Synopsis Point Defect Calculations in Tungsten by : Ronald L. Danilowicz

Download or read book Point Defect Calculations in Tungsten written by Ronald L. Danilowicz and published by . This book was released on 1968 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Calculations were made with a computer code developed for making point-defect calculations in body-centered-cubic metals. A Semi-empirical cubic potential based on experimental data was also developed for tungsten for these calculations. The vacancy migration energy for tungsten was calculated. The calculated value of 1.73 electron volts, together with experimental data, suggests that vacancies migrate in stage III recovery in tungsten. The formation energies for six possible equilibrium interstitial configurations were also calculated. The (110) split interstitial was the most stable configuration for tungsten with a formation energy of 9.73 electron volts.

Simulating the Production of Free Defects in Irradiated Metals

Author :
Publisher :
ISBN 13 :
Total Pages : 14 pages
Book Rating : 4.:/5 (685 download)

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Book Synopsis Simulating the Production of Free Defects in Irradiated Metals by :

Download or read book Simulating the Production of Free Defects in Irradiated Metals written by and published by . This book was released on 1994 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Under cascade-producing irradiation by high energy neutrons or charged particles, only a small fraction of the initially displaced atoms contribute to the population of free defects, i.e. those that are available to migrate throughout the metal and cause microstructural changes. Although, in principle, computer simulations of free defect production could best be done using molecular dynamics, in practice, the wide ranges of time and distance scales involved can be done only by a combination of atomistic models that employ various levels of approximation. An atomic-scale, multimodel approach has been developed that combines molecular dynamics, binary collision models and stochastic annealing simulation. The annealing simulation is utilized in calibrating binary collision simulations to the results of molecular dynamics calculations, as well as to model the subsequent migration of the defects on more macroscopic time and size scales. The annealing simulation and the method of calibrating the multimodel approach are discussed, and the results of simulations of cascades in copper are presented. The temperature dependence of free defect production following simulated annealing of isolated cascades in copper shows a differential in the fractions of free vacancies and interstitial defects escaping from the cascade above Stage V. This differential, a consequence of the direct formation of interstitial clusters in cascades and the relative thermal stability of vacancy and interstitial clusters du ring subsequent annealing, is the basis for the production bias mechanism of void swelling.

Energy Research Abstracts

Author :
Publisher :
ISBN 13 :
Total Pages : 508 pages
Book Rating : 4.0/5 ( download)

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Book Synopsis Energy Research Abstracts by :

Download or read book Energy Research Abstracts written by and published by . This book was released on 1994-12 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Surface Response of Tungsten to Helium and Hydrogen Plasma Flux as a Function of Temperature and Incident Kinetic Energy

Author : Faiza Sefta
Publisher :
ISBN 13 :
Total Pages : 128 pages
Book Rating : 4.:/5 (94 download)

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Book Synopsis Surface Response of Tungsten to Helium and Hydrogen Plasma Flux as a Function of Temperature and Incident Kinetic Energy by : Faiza Sefta

Download or read book Surface Response of Tungsten to Helium and Hydrogen Plasma Flux as a Function of Temperature and Incident Kinetic Energy written by Faiza Sefta and published by . This book was released on 2013 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tungsten is a leading candidate material for the diverter in future nuclear fusion reactors. Previous experiments have demonstrated that surface defects and bubbles form in tungsten when ex- posed to helium and hydrogen plasmas, even at modest ion energies. In some regimes, between 1000K and 2000K, and for He energies below 100eV, "fuzz" like features form. The mechanisms leading to these surfaces comprised of nanometer sized tungsten tendrils which include visible helium bubbles are not currently known. The role of helium bubble formation in tendril morphology could very likely be the starting point of these mechanisms. Using Molecular dynamics (MD) simulations, the role of helium and hydrogen exposure in the initial formation mechanisms of tungsten "fuzz" are investigated. Molecular dynamics simulations are well suited to describe the time and length scales associated with initial formation of helium clusters that eventually grow to nano-meter sized helium bubbles. MD simulations also easily enable the modeling of a variety of surfaces such as single crystals, grain boundaries or "tendrils". While the sputtering yield of tungsten is generally low, previous observations of surface modification due to plasma exposure raise questions about the effects of surface morphology and sub-surface helium bubble populations on the sputtering behavior. Results of computational molecular dynamics are reported that investigate the influence of sub-surface helium bubble distributions on the sputtering yield of tungsten (100) and (110) surfaces induced by helium ion exposure in the range of 300 eV to 1 keV. The calculated sputtering yields are in reasonable agreement with a wide range of experimental data; but do not show any significant variation as a result of the pre-existing helium bubbles. Molecular dynamics simulations reveal a number of sub-surface mechanisms leading to nanometer- sized "fuzz" in tungsten exposed to low-energy helium plasmas. We find that during the bubble formation process, helium clusters create self-interstitial defect clusters in tungsten by a trap mutation process, followed by the migration of these defects to the surface that leads to the formation of layers of adatom islands on the tungsten surface. As the helium clusters grow into nanometer sized bubbles, their proximity to the surface and extremely high gas pressures can cause them to rupture the surface thus enabling helium release. Helium bubble bursting induces additional surface damage and tungsten mass loss which varies depending on the nature of the surface. We then show tendril-like geometries have surfaces that are more resilient to helium clustering and bubble formation and rupture. Finally, the study includes hydrogen to reveal the effect of a mixed 90%H-10%He plasma mix on the tungsten surface. We find that hydrogen greatly affects the tungsten surface, with a near surface hydrogen saturation layer, and that helium clusters still form and are attractive trapping sites for hydrogen. Molecular dynamics simulations have also investigated the effect of sub-surface helium bubble evolution on tungsten surface morphology. The helium bubble/tungsten surface interaction has been systematically studied to determine how parameters such as bubble shape and size, temperature, tungsten surface orientation and ligament thickness above the bubble impact bubble stability and surface evolution. The tungsten surface is roughened by a combination of adatom islands, craters and pinholes. The study provides insight into the mechanisms and conditions leading to various tungsten topology changes, most notably the formation of nanoscale fuzz. An atomistic study of the mechanisms behind initial phases of tungsten nano-fuzz growth has determined that tungsten surfaces are affected by sub-displacement energy helium and hydrogen fluxes through a series of mechanisms. Sub-surface helium atom clustering, bubble nucleation, growth and rupture lead to tungsten surface deformation. Helium clustering processes vary near grain boundaries or in tendril-like surface geometries. In the presence of hydrogen, these mechanisms are coupled with hydrogen surface saturation. Finally, further investigation to connect these atomistic mechanisms to nano-size tungsten fuzz growth is needed to get a comprehensive under- standing of the effects of low energy helium and hydrogen on tungsten.

Scientific and Technical Aerospace Reports

Author :
Publisher :
ISBN 13 :
Total Pages : 1370 pages
Book Rating : 4.:/5 (31 download)

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Book Synopsis Scientific and Technical Aerospace Reports by :

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1981 with total page 1370 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Fundamentals of Radiation Materials Science

Author : GARY S. WAS
Publisher : Springer
ISBN 13 : 1493934384
Total Pages : 1014 pages
Book Rating : 4.4/5 (939 download)

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Book Synopsis Fundamentals of Radiation Materials Science by : GARY S. WAS

Download or read book Fundamentals of Radiation Materials Science written by GARY S. WAS and published by Springer. This book was released on 2016-07-08 with total page 1014 pages. Available in PDF, EPUB and Kindle. Book excerpt: The revised second edition of this established text offers readers a significantly expanded introduction to the effects of radiation on metals and alloys. It describes the various processes that occur when energetic particles strike a solid, inducing changes to the physical and mechanical properties of the material. Specifically it covers particle interaction with the metals and alloys used in nuclear reactor cores and hence subject to intense radiation fields. It describes the basics of particle-atom interaction for a range of particle types, the amount and spatial extent of the resulting radiation damage, the physical effects of irradiation and the changes in mechanical behavior of irradiated metals and alloys. Updated throughout, some major enhancements for the new edition include improved treatment of low- and intermediate-energy elastic collisions and stopping power, expanded sections on molecular dynamics and kinetic Monte Carlo methodologies describing collision cascade evolution, new treatment of the multi-frequency model of diffusion, numerous examples of RIS in austenitic and ferritic-martensitic alloys, expanded treatment of in-cascade defect clustering, cluster evolution, and cluster mobility, new discussion of void behavior near grain boundaries, a new section on ion beam assisted deposition, and reorganization of hardening, creep and fracture of irradiated materials (Chaps 12-14) to provide a smoother and more integrated transition between the topics. The book also contains two new chapters. Chapter 15 focuses on the fundamentals of corrosion and stress corrosion cracking, covering forms of corrosion, corrosion thermodynamics, corrosion kinetics, polarization theory, passivity, crevice corrosion, and stress corrosion cracking. Chapter 16 extends this treatment and considers the effects of irradiation on corrosion and environmentally assisted corrosion, including the effects of irradiation on water chemistry and the mechanisms of irradiation-induced stress corrosion cracking. The book maintains the previous style, concepts are developed systematically and quantitatively, supported by worked examples, references for further reading and end-of-chapter problem sets. Aimed primarily at students of materials sciences and nuclear engineering, the book will also provide a valuable resource for academic and industrial research professionals. Reviews of the first edition: "...nomenclature, problems and separate bibliography at the end of each chapter allow to the reader to reach a straightforward understanding of the subject, part by part. ... this book is very pleasant to read, well documented and can be seen as a very good introduction to the effects of irradiation on matter, or as a good references compilation for experimented readers." - Pauly Nicolas, Physicalia Magazine, Vol. 30 (1), 2008 “The text provides enough fundamental material to explain the science and theory behind radiation effects in solids, but is also written at a high enough level to be useful for professional scientists. Its organization suits a graduate level materials or nuclear science course... the text was written by a noted expert and active researcher in the field of radiation effects in metals, the selection and organization of the material is excellent... may well become a necessary reference for graduate students and researchers in radiation materials science.” - L.M. Dougherty, 07/11/2008, JOM, the Member Journal of The Minerals, Metals and Materials Society.

University Physics

Author : Samuel J. Ling
Publisher :
ISBN 13 : 9789888407613
Total Pages : 818 pages
Book Rating : 4.4/5 (76 download)

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Book Synopsis University Physics by : Samuel J. Ling

Download or read book University Physics written by Samuel J. Ling and published by . This book was released on 2017-12-19 with total page 818 pages. Available in PDF, EPUB and Kindle. Book excerpt: University Physics is designed for the two- or three-semester calculus-based physics course. The text has been developed to meet the scope and sequence of most university physics courses and provides a foundation for a career in mathematics, science, or engineering. The book provides an important opportunity for students to learn the core concepts of physics and understand how those concepts apply to their lives and to the world around them. Due to the comprehensive nature of the material, we are offering the book in three volumes for flexibility and efficiency. Coverage and Scope Our University Physics textbook adheres to the scope and sequence of most two- and three-semester physics courses nationwide. We have worked to make physics interesting and accessible to students while maintaining the mathematical rigor inherent in the subject. With this objective in mind, the content of this textbook has been developed and arranged to provide a logical progression from fundamental to more advanced concepts, building upon what students have already learned and emphasizing connections between topics and between theory and applications. The goal of each section is to enable students not just to recognize concepts, but to work with them in ways that will be useful in later courses and future careers. The organization and pedagogical features were developed and vetted with feedback from science educators dedicated to the project. VOLUME II Unit 1: Thermodynamics Chapter 1: Temperature and Heat Chapter 2: The Kinetic Theory of Gases Chapter 3: The First Law of Thermodynamics Chapter 4: The Second Law of Thermodynamics Unit 2: Electricity and Magnetism Chapter 5: Electric Charges and Fields Chapter 6: Gauss's Law Chapter 7: Electric Potential Chapter 8: Capacitance Chapter 9: Current and Resistance Chapter 10: Direct-Current Circuits Chapter 11: Magnetic Forces and Fields Chapter 12: Sources of Magnetic Fields Chapter 13: Electromagnetic Induction Chapter 14: Inductance Chapter 15: Alternating-Current Circuits Chapter 16: Electromagnetic Waves

Positron Spectroscopy of Solids

Author : Società italiana di fisica
Publisher : IOS Press
ISBN 13 : 1614992118
Total Pages : 807 pages
Book Rating : 4.6/5 (149 download)

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Book Synopsis Positron Spectroscopy of Solids by : Società italiana di fisica

Download or read book Positron Spectroscopy of Solids written by Società italiana di fisica and published by IOS Press. This book was released on 1995 with total page 807 pages. Available in PDF, EPUB and Kindle. Book excerpt: The lifetime of a positron inside a solid is normally less than a fraction of nanosecond. This is a very short time on a human scale, but is long enough to enable the positron to visit an extended region of the material, and to sense the atomic and electronic structure of the environment. Thus, we can inject a positron in a sample to draw from it some signal giving us information on the microscopic properties of the material. This idea has been successfully developed in a number of positron-based techniques of physical analysis, with resolution in energy, momentum, or position. The complex of these techniques is what we call now positron spectroscopy of solids. The field of application of the positron spectroscopy extends from advanced problems of solid-state physics to industrial applications in the area of characterization of high-tech materials. This volume focuses the attention on the physics that can be learned from positron-based methods, but also frames those methods in a wider context including other experimental approaches. It can be considered as a textbook on positron spectroscopy of solids, the sort of book that the newcomer takes for his approach to this field, but also as a useful research tool for the expert.

The Engineering Properties of Tungsten and Tungsten Alloys

Author : F. F. Schmidt
Publisher :
ISBN 13 :
Total Pages : 154 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis The Engineering Properties of Tungsten and Tungsten Alloys by : F. F. Schmidt

Download or read book The Engineering Properties of Tungsten and Tungsten Alloys written by F. F. Schmidt and published by . This book was released on 1963 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of a state-of-the-art survey covering tungsten and ten of its alloys are presented. All data are given in tabular and graphical form covering some of the more important physical, mechanical, and metallurgical properties for each material. References are given at the conclusion of each material section.

Management of Ageing in Graphite Reactor Cores

Author : Gareth B. Neighbour
Publisher : Royal Society of Chemistry
ISBN 13 : 0854043454
Total Pages : 313 pages
Book Rating : 4.8/5 (54 download)

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Book Synopsis Management of Ageing in Graphite Reactor Cores by : Gareth B. Neighbour

Download or read book Management of Ageing in Graphite Reactor Cores written by Gareth B. Neighbour and published by Royal Society of Chemistry. This book was released on 2007 with total page 313 pages. Available in PDF, EPUB and Kindle. Book excerpt: This product is not available separately, it is only sold as part of a set. There are 750 products in the set and these are all sold as one entity. This product is not available separately, it is only sold as part of a set. There are 750 products in the set and these are all sold as one entity.

Thermally Activated Mechanisms in Crystal Plasticity

Author : D. Caillard
Publisher : Elsevier
ISBN 13 : 0080542786
Total Pages : 453 pages
Book Rating : 4.0/5 (85 download)

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Book Synopsis Thermally Activated Mechanisms in Crystal Plasticity by : D. Caillard

Download or read book Thermally Activated Mechanisms in Crystal Plasticity written by D. Caillard and published by Elsevier. This book was released on 2003-09-08 with total page 453 pages. Available in PDF, EPUB and Kindle. Book excerpt: KEY FEATURES: A unified, fundamental and quantitative resource. The result of 5 years of investigation from researchers around the world New data from a range of new techniques, including synchrotron radiation X-ray topography provide safer and surer methods of identifying deformation mechanisms Informing the future direction of research in intermediate and high temperature processes by providing original treatment of dislocation climb DESCRIPTION: Thermally Activated Mechanisms in Crystal Plasticity is a unified, quantitative and fundamental resource for material scientists investigating the strength of metallic materials of various structures at extreme temperatures. Crystal plasticity is usually controlled by a limited number of elementary dislocation mechanisms, even in complex structures. Those which determine dislocation mobility and how it changes under the influence of stress and temperature are of key importance for understanding and predicting the strength of materials. The authors describe in a consistent way a variety of thermally activated microscopic mechanisms of dislocation mobility in a range of crystals. The principles of the mechanisms and equations of dislocation motion are revisited and new ones are proposed. These describe mostly friction forces on dislocations such as the lattice resistance to glide or those due to sessile cores, as well as dislocation cross-slip and climb. They are critically assessed by comparison with the best available experimental results of microstructural characterization, in situ straining experiments under an electron or a synchrotron beam, as well as accurate transient mechanical tests such as stress relaxation experiments. Some recent attempts at atomistic modeling of dislocation cores under stress and temperature are also considered since they offer a complementary description of core transformations and associated energy barriers. In addition to offering guidance and assistance for further experimentation, the book indicates new ways to extend the body of data in particular areas such as lattice resistance to glide.

Radiation Oncology Physics

Author : International Atomic Energy Agency
Publisher : IAEA
ISBN 13 :
Total Pages : 704 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis Radiation Oncology Physics by : International Atomic Energy Agency

Download or read book Radiation Oncology Physics written by International Atomic Energy Agency and published by IAEA. This book was released on 2005 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt: This publication is aimed at students and teachers involved in teaching programmes in field of medical radiation physics, and it covers the basic medical physics knowledge required in the form of a syllabus for modern radiation oncology. The information will be useful to those preparing for professional certification exams in radiation oncology, medical physics, dosimetry or radiotherapy technology.