Download or read book Phase Stability Under Irradiation of Precipitates and Solid Solutions in Model ALloys and in ODS Alloys Relevant for Gen IV written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall objective of this program is to investigate the irradiation-altered phase stability of oxide precipitates in ODS steels and of model alloy solid solutions of associated systems. This information can be used to determine whether the favorable mechanical propertiies of these steels are maintained under irradiation, thus addressing one of the main materials research issues for this class of steels as identified by the GenIV working groups. The research program will also create fundamental understanding of the irradiation precipitation/dissolution problem by studying a "model" system in which the variables can be controlled and their effects understood individually.

Download or read book Phase Stability in Metals and Alloys written by Battelle Memorial Institute and published by . This book was released on 1967 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structural and Phase Stability of Alloys written by J. L. Morán-López and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 269 pages. Available in PDF, EPUB and Kindle. Book excerpt: This vohune contains the papers presented at the Adriatico Research Conference on Structural and Phase Stability of Alloys held in Trieste, Italy, in May 1991, under the auspices of the International Centre for Theoretical Physics. The conference brought together participants with a variety of interests in theoretical and experimental aspects of alloys from Argentina, Belgium, Bulgaria, Czechslovakia, France, Germany, Italy, Japan, Mexico, People's Republic of Congo,Portugal, Switzerland, United Kingdom, United States, U. S. S. R. , and Venezuela. The conference was purposely designed to succinctly cover experimental and the oretical aspects of magnetic and non-magnetic alloys, surfaces, thin films and nanos tructures. The Conference opened with an overview of a select class of advanced structural materials, with a potential in engineering applications, for which the con ventional "physics" approach, both theoretical and experimental, should have a sig nificant impact. A number of papers were dedicated to the use of phenomenological approaches for the description of thermodynamic bulk and surface properties. It was clear from these presentations that the phenomenological models and simulations in alloy theory have reached a high degree of sophistication. Although with somewhat limited predictive powers, the phenomenological models provide a valuable tool for the understanding of a variety of subtle phenomena such as short-range order, phase stability, kinetics and the thermodynamics of surfaces and antiphase boundaries, to name a few.

Download or read book Alloy Phase Stability written by G.M. Stocks and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 638 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the ultimate goals of materials research is to develop a fun damental and predictive understanding of the physical and metallurgical properties of metals and alloys. Such an understanding can then be used in the design of materials having novel properties or combinations of proper ties designed to meet specific engineering applications. The development of new and useful alloy systems and the elucidation of their properties are the domain of metallurgy. Traditionally, the search for new alloy systems has been conducted largely on a trial and error basis, guided by the skill and intuition of the metallurgist, large volumes of experimental data, the principles of 19th century thermodynamics and ad hoc semi-phenomenological models. Recently, the situation has begun to change. For the first time, it is possible to understand the underlying mechanisms that control the formation of alloys and determine their properties. Today theory can begin to offer guidance in predicting the properties of alloys and in developing new alloy systems. Historically, attempts directed toward understanding phase stability and phase transitions have proceeded along distinct and seemingly diverse lines. Roughly, we can divide these approaches into the following broad categories. 1. Experimental determination of phase diagrams and related properties, 2. Thermodynamic/statistical mechanical approaches based on semi phenomenological models, and 3. Ab initio quantum mechanical methods. Metallurgists have traditionally concentrated their efforts in cate gories 1 and 2, while theoretical physicists have been preoccupied with 2 and 3.

Download or read book Order and Phase Stability in Alloys written by F. Ducastelle and published by North Holland. This book was released on 1991 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hardbound. The main purpose of this book is to describe the modern tools of solid state physics (in particular, electronic structure calculations and statistical thermodynamics) that enable us to understand ordering effects in alloys and to determine phase diagrams. This approach is used more to throw light on the most important physical mechanisms rather than to be able to make accurate predictions suitable for particular applications. On the other hand, more phenomenological, practically oriented approaches can expand the scope of these new theoretical insights. A second purpose of the book is to show that materials science can provide wonderful and too often ignored examples to test and discuss the most fundamental physical theories. For example, many real alloys on a face centered cubic lattice are marvellous examples of the Ising model on this lattice with many different ordered structures, commensurate or not.The text is therefore defi

Download or read book Statics and Dynamics of Alloy Phase Transformations written by Patrice E.A. Turchi and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 725 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of phase transformations in substitutional alloys, including order disorder phenomena and structural transformations, plays a crucial role in understanding the physical and mechanical properties of materials, and in designing alloys with desired technologically important characteristics. Indeed, most of the physical properties, including equilibrium properties, transport, magnetic, vibrational as well as mechanical properties of alloys are often controlled by and are highly sensitive to the existence of ordered compounds and to the occurrence of structural transformations. Correspondingly, the alloy designer facing the task of processing new high-performance materials with properties that meet specific industrial applications must answer the following question: What is the crystalline structure and the atomic configuration that an alloy may exhibit at given temperature and concentration? Usually the answer is sought in the phase-diagram of a relevant system that is often determined experimentally and does not provide insight to the underlying mechanisms driving phase stability. Because of the rather tedious and highly risky nature of developing new materials through conventional metallurgical techniques, a great deal of effort has been expended in devising methods for understanding the mechanisms contrOlling phase transformations at the microscopic level. These efforts have been bolstered through the development of fully ab initio, accurate theoretical models, coupled with the advent of new experimental methods and of powerful supercomputer capabilities.

Download or read book Phase Stability in High Temperature Alloys written by Viktor Guttmann and published by . This book was released on 1981 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Alloy Phase Stability and Design Volume 186 written by G. Malcolm Stocks and published by Mrs Proceedings. This book was released on 1991 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: The MRS Symposium Proceeding series is an internationally recognised reference suitable for researchers and practitioners.

Download or read book Phase and Microstructural Stability in Immiscible Binary Alloys Under Irradiation written by Raul Alejandro Enrique and published by . This book was released on 2001 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Radiation Modified Phase Diagrams of Binary Alloys written by AS. Bakai and published by . This book was released on 1992 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: A model for radiation-induced segregation in concentrated binary alloys is described. The model is used to investigate the general properties of quasistationary distributions of point defects and solute in an irradiated alloy with sinks but without precipitates and stress fields. In spite of compositional gradients around sinks arising due to the inverse Kirkendall effect, all sinks remain unbiased toward absorption of defects of a certain species. To derive the rate equations, an effective medium approach for binary alloys is formulated and compared to current ones for pure metals. Considerable difference between growth rates of coherent and incoherent precipitates under irradiation is revealed. The criterion for precipitate stability is expressed in terms of solute solubility. It is shown that irradiation strongly affects the incoherent solubility, whereas the coherent one remains unaltered. A method is presented to construct the radiation-modified phase diagram as well as the temperature-dose rate diagram. The calculations of diagrams are performed for Ni-Si, Ni-Al, and Al-Zn alloys. The comparison of the computed diagrams with the available experimental diagrams is carried out for the Al-Zn alloy.

Download or read book Metals Abstracts written by and published by . This book was released on 1996 with total page 1628 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Phase Transformations in Solids written by National Research Council (U.S.). Committee on Solids and published by . This book was released on 1951 with total page 678 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Phase Stability in Irradiated Alloys by Constrained Equilibrium Thermodynamics written by JP. Holloway and published by . This book was released on 1985 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: A set of equilibrium thermodynamics relationships are developed to account for the effects of fixed levels of interstitials and vacancies on phase free energy in binary alloys. Such defects would typically be found in alloys under irradiation, and could account for shifts in phase solubility limits and stable temperature ranges. While the total defect concentrations are fixed, no external constraints are placed on the distribution in types of interstitials. These distributions and the alloy phase compositions are allowed to adjust to minimize the system free energy and predict the constrained thermodynamic equilibrium phase structures.

Download or read book Mechanisms of Diffusional Phase Transformations in Metals and Alloys written by Hubert I. Aaronson and published by CRC Press. This book was released on 2016-04-19 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt: Developed by the late metallurgy professor and master experimentalist Hubert I. Aaronson, this collection of lecture notes details the fundamental principles of phase transformations in metals and alloys upon which steel and other metals industries are based. Mechanisms of Diffusional Phase Transformations in Metals and Alloys is devoted to solid-s

Download or read book High Entropy Alloys written by Michael C. Gao and published by Springer. This book was released on 2016-04-27 with total page 524 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a systematic and comprehensive description of high-entropy alloys (HEAs). The authors summarize key properties of HEAs from the perspective of both fundamental understanding and applications, which are supported by in-depth analyses. The book also contains computational modeling in tackling HEAs, which help elucidate the formation mechanisms and properties of HEAs from various length and time scales.

Download or read book Phase Field Modeling of Precipitation in Metallic Alloys written by Yanzhou Ji and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Precipitation hardening is an important strengthening mechanism in metallic alloys, which is realized by impeding the dislocation motions in the matrix via stress field due to the precipitate/matrix lattice mismatch. The precipitation hardening effect is largely determined by a series of inter-correlated factors including the feature and evolution of precipitate morphologies, e.g., the size, shape, volume fraction and spatial distribution of the precipitate and their evolution; the coherency state of the precipitate; and the detailed precipitate-dislocation interaction mechanisms. Therefore, understanding and quantifying the morphology and kinetics of precipitation is an important step towards the estimation of precipitation hardening effects, as well as the proper design of alloys and the optimization of thermo-mechanical processing routes.The phase-field approach, as a powerful meso-scale simulation method, has been successfully applied to understand the precipitation phenomena. However, there are still several remaining challenges for precipitation phase-field models. In this thesis work, the precipitation phase-field models have been further extended and applied to deal with precipitate phases with different thermodynamic descriptions, to predict the morphology evolution and kinetics of fully coherent and semi-coherent precipitates with the help of first-principles calculations, to predict the possible dislocation evolution pathway and morphology evolution during the sequential coherency loss of an initially coherent or semi-coherent precipitate, to understand the competitions between the diffusional and diffusionless transformation mechanisms, and to provide necessary information for theoretical precipitation hardening models.The precipitate phase, depending on the specific materials systems, can be treated using solid solution model, sublattice model, or stoichiometric compounds (line compounds). To deal with these different treatments, we use the Kim-Kim-Suzuki model for the solid solution and sublattice cases, where the equal diffusion chemical potential of alloying elements is assumed to remove the extra potential at the interface. An internal equilibrium is assumed for the sublattice model within different sublattices which converts the sublattice site fractions to alloy compositions. To deal with the precipitation of line compounds, we develop a phase-field model for chemical reactions, which can capture both the solute diffusion in the matrix phase and the linear chemical reaction kinetics.The phase-field model is then applied to investigate the precipitate morphology, kinetics and hardening effect of the fully coherent -Mg7Nd in Mg-Nd alloys. The necessary input parameters, including the formation energies, lattice constants and elastic constants of both the Mg matrix and the phase, as well as the anisotropic interfacial energies, are all obtained from first-principles calculations. Especially, the formation energies of the slightly off-stoichiometric Mg7Nd compound are also calculated, which are used to fit the formation energies of into a parabolic function of solute composition. The interplay between the anisotropies in misfit strain energy and interfacial energy is discussed in detail, showing their dominance in determining the precipitate morphology at different aging stages. The simulated morphology, with both anisotropies considered, is consistent with experimental observations. Theoretical models based on Orowans equation is used to predict the hardening effect of -Mg7Nd.The phase-field model, with similar thermodynamic treatment of the precipitate phase to that of -Mg7Nd, is further applied to the semi-coherent -Al2Cu in Al-Cu-based alloys. To more accurately simulate the precipitation kinetics, a temperature-dependent nucleation model, with necessary input from experimental observations, and a more accurate parameterization of interface kinetic coefficient, are considered in the model. The phase-field simulations, with materials parameters from validated sources, are performed for isothermal aging at 463 K, 503 K and 533 K. The simulated is of disk shape under the anisotropies of misfit strain energy, interfacial energy and interface mobility. The predicted precipitation kinetics, including the evolution of mean diameters, mean thicknesses and volume fractions, show acceptable agreement with experimental measurements. Possible model improvements and extensions to minimize the discrepancies are discussed.Coherency loss of the initially coherent or semi-coherent precipitate during continued precipitate growth is a manifestation of energy minimization, which relaxes the misfit strain energy at the expense of increasing the interfacial energy by creating line defects at the matrix/precipitate interface. To understand the kinetics of coherency loss, as well as its effect on precipitate morphology, kinetics and hardening effects, we equivalently consider the effect of line defects, as well as the evolution of their average spacings, on the formulation of misfit strain energies and interfacial energies in the phase-field model. We apply this model to -Ni3Nb in IN718, where is treated using the sublattice model, to predict the critical size to trigger the coherency loss under different criteria and a known dislocation configuration at interfaces. We further apply the model to predict the sequential loss of coherency in -Al2Cu, which predicts a coherency loss pathway with the minimum energy cost.Diffusional precipitation transformation can change its transformation mechanism with the change of alloy composition, temperature and cooling rates. For example, in Ti-6Al-4V, start from phase, the phase can be a diffusional product during isothermal aging or slow cooling, while becomes diffusionless product during fast cooling. To understand this competition, we combine the graphical thermodynamic approach to predict the possible transformation pathways, and the phase-field simulation to predict the microstructure evolution during continuous cooling of Ti-6Al-4V. The simulated (+) morphologies are attributed to the interplay between the diffusional and diffusionless mechanisms, as well as that between the nucleation and growth of phase.

Download or read book The Science of Complex Alloy Phases written by Thaddeus B. Massalski and published by Wiley-TMS. This book was released on 2005 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This volume contains the proceedings of the symposium entitled "The Science of Complex Alloy Phases" ... held during the 134th TMS Annual Meting and Exposition in San Francisco, California, USA, February 13-17, 2005 ..."--P. vii.