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Author: Guanyu Yi
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
A front-tracking solidification model has been developed to simulate the dendritic structure evolution during alloy solidification. In the model the growth of dendrites is governed by heat and mass transport and a finite difference technique is employed to solve heat and solute diffusion during solidification. The model incorporates front-tracking technique to calculate and track the exact position of the Solid/Liquid (S/L) interface as a part of solution process and a new capture rule was designed and implemented in the model to efficiently track the growing S/L interface. The model has been evaluated and verified using simulated data from Al-Cu 4 wt. % alloy solidification. The effect of curvature undercooling on crystal growth was investigated. The simulated results reveal that solute redistribution, curvature of the S/L interface and anisotropy of interface tension are important factors in determining the dendritic morphology. The calculation of the S/L interface curvature and anisotropy of surface tension was found to be particularly important in determining the dendritic growth direction. Based on the above observations and simulated data, the parameters in the developed model have been optimised for predicting the solidification structure in binary alloys. Simulations of Al-Cu alloy solidification were then performed using the optimised model for single-grain and multi-grain solidification. The simulated results of single-grain growth were compared with the results from the Lipton-Glicksman-Kurz (LGK) model (Lipton et al. 1984). Solute profile ahead of the S/L interface was examined using different techniques for approximating solute profile in the growing cell. The solidification segregation in the multi-grain growth was investigated; and the dendritic evolution and solute interaction during multi-grain growth were investigated.
Author: Guanyu Yi
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
A front-tracking solidification model has been developed to simulate the dendritic structure evolution during alloy solidification. In the model the growth of dendrites is governed by heat and mass transport and a finite difference technique is employed to solve heat and solute diffusion during solidification. The model incorporates front-tracking technique to calculate and track the exact position of the Solid/Liquid (S/L) interface as a part of solution process and a new capture rule was designed and implemented in the model to efficiently track the growing S/L interface. The model has been evaluated and verified using simulated data from Al-Cu 4 wt. % alloy solidification. The effect of curvature undercooling on crystal growth was investigated. The simulated results reveal that solute redistribution, curvature of the S/L interface and anisotropy of interface tension are important factors in determining the dendritic morphology. The calculation of the S/L interface curvature and anisotropy of surface tension was found to be particularly important in determining the dendritic growth direction. Based on the above observations and simulated data, the parameters in the developed model have been optimised for predicting the solidification structure in binary alloys. Simulations of Al-Cu alloy solidification were then performed using the optimised model for single-grain and multi-grain solidification. The simulated results of single-grain growth were compared with the results from the Lipton-Glicksman-Kurz (LGK) model (Lipton et al. 1984). Solute profile ahead of the S/L interface was examined using different techniques for approximating solute profile in the growing cell. The solidification segregation in the multi-grain growth was investigated; and the dendritic evolution and solute interaction during multi-grain growth were investigated.
Author: Nikolas Provatas
Publisher: CRC Press
ISBN: 1000435008
Category : Science
Languages : en
Pages : 186
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Book Description
This book presents a study of phase field modelling of solidification in metal alloy systems. It is divided in two main themes. The first half discusses several classes of quantitative multi-order parameter phase field models for multi-component alloy solidification. These are derived in grand potential ensemble, thus tracking solidification in alloys through the evolution of the chemical potentials of solute species rather than the more commonly used solute concentrations. The use of matched asymptotic analysis for making phase field models quantitative is also discussed at length, and derived in detail in order to make this somewhat abstract topic accessible to students. The second half of the book studies the application of phase field modelling to rapid solidification where solute trapping and interface undercooling follow highly non-equilibrium conditions. In this limit, matched asymptotic analysis is used to map phase field evolution equations onto the continuous growth model, which is generally accepted as a sharp-interface description of solidification at rapid solidification rates. This book will be of interest to graduate students and researchers in materials science and materials engineering. Key Features Presents a clear path to develop quantitative multi-phase and multi-component phase field models for solidification and other phase transformation kinetics Derives and discusses the quantitative nature of the model formulations through matched interface asymptotic analysis Explores a framework for quantitative treatment of rapid solidification to control solute trapping and solute drag dynamics
Author: Shuan McFadden
Publisher:
ISBN:
Category : Alloys
Languages : en
Pages : 137
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Book Description
Author: Dmitry G. Eskin
Publisher: Springer
ISBN: 3319948423
Category : Technology & Engineering
Languages : en
Pages : 323
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Book Description
This book explores the application of external physical fields to the solidification processing of metallic alloys. Leading academics from around the world present comprehensive and critical reviews on state-of-the-art research and discuss possible future directions. Major physical fields, including electromagnetic, electric, acoustic, and thermal, are considered. In addition, the most advanced synchrotron X-ray based real-time and in-situ studies and numerical modeling methodologies are reviewed and discussed, with a special emphasis on their applications to the solidification processes. Throughout, all chapters are illustrated with both historical and very recent research cases, including typical examples of in-situ studies, modeling, and simulation. This book contains essential knowledge and information suitable for a wide audience, from undergraduate and postgraduate students to academics, practicing researchers, and engineers in materials, metallurgy, and manufacturing.
Author: Lijian Tan
Publisher:
ISBN:
Category :
Languages : en
Pages : 438
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Book Description
Modeling solidification in the micro-scale is computationally intensive. To overcome this difficulty, a method combining features of front-tracking methods and fixed-domain methods is developed. To explicitly track the interface growth and shape of the solidifying crystals, a front-tracking approach based on the level set method is implemented. To easily model the heat and momentum transport, a fixed-domain method is implemented assuming a diffused freezing front where the liquid fraction is defined in terms of the level set function. The fixed-domain approach, by avoiding the explicit application of essential boundary conditions on the freezing front, leads to an energy conserving methodology that is not sensitive to the mesh size. Techniques including fast marching, narrow band computing and adaptive meshing are utilized to speed up computations. The model is used to investigate various phenomena in solidification including two- and three-dimensional dendrite growth of pure material and alloys, eutectic and peritectic solidification, convection effects on crystal and dendrite growth, planar/cellular/dendritic transition, interaction between multiple dendrites, columnar/equiaxed transition and etc. Interaction between thousands or even millions of crystals gives the overall behavior of the solidification process and defines the properties of the final product. A multiscale model based on a database approach is developed to investigate alloy solidification. Appropriate assumptions are introduced to describe the behavior of macroscopic temperature, macroscopic concentration, liquid volume fraction and microstructure features. These assumptions lead to a macroscale model with two unknown functions: liquid vol- ume fraction and microstructure features. These functions are computed using information from microscale solutions of selected problems. A computationally efficient model, which is different from the microscale and macroscale models, is utilized to find relevant sample problems. The microscale solution of the relevant sample problems is then utilized to evaluate the two unknown functions (liquid volume fraction and microstructure features) in the macroscale model. The temperature solution of the macroscale model is further used to improve the estimation of the liquid volume fraction and microstructure features. Interpolation is utilized in the feature space to greatly reduce the number of required sample problems. The efficiency of the proposed multiscale framework is demonstrated with numerical examples that consider a large number of crystals. A computationally intensive fully-resolved microscale analysis is also performed to evaluate the accuracy of the multiscale framework. (Abstract).
Author: Laurentiu Nastac
Publisher: Springer Science & Business Media
ISBN: 1402078323
Category : Technology & Engineering
Languages : en
Pages : 298
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Book Description
The aim of Modeling and Simulation of Microstructure Evolution in Solidifying Alloys is to describe in a clear mathematical language the physics of the solidification structure evolution of cast alloys. The concepts and methodologies presented here for the net-shaped casting and the ingot remelt processes can be applied, with some modifications, to model other solidification processes such as welding and deposition processes. Another aim of the book is to provide simulation examples of the solidification structure modeling in some crucial commercial casting technologies as well as to provide practical techniques for controlling the structure formation during the solidification processes.
Author: Doru Michael Stefanescu
Publisher: Springer Science & Business Media
ISBN: 0387746129
Category : Science
Languages : en
Pages : 413
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Book Description
Stefanescu here attempts to describe solidification theory through the complex mathematical apparatus required for a fundamental treatment of the problem. The mathematics is however restricted to the elements essential to attain a working knowledge in the field. This is in line with the main goal of the book, which is to educate the reader in the fast moving area of computational modeling of solidification of castings. A special effort has been made to introduce the reader to the latest developments in solidification theory including, in this second edition, a new chapter on semi-solid casting.
Author: Doru Michael Stefanescu
Publisher: Springer
ISBN: 3319156934
Category : Technology & Engineering
Languages : en
Pages : 559
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Book Description
The 3rd edition of this popular textbook covers current topics in all areas of casting solidification. Partial differential equations and numerical analysis are used extensively throughout the text, with numerous calculation examples, to help the reader in achieving a working knowledge of computational solidification modeling. The features of this new edition include: • new chapters on semi-solid and metal matrix composites solidification • a significantly extended treatment of multiscale modeling of solidification and its applications to commercial alloys • a survey of new topics such as solidification of multicomponent alloys and molecular dynamic modeling • new theories, including a theory on oxide bi-films in the treatment of shrinkage problems • an in-depth treatment of the theoretical aspects of the solidification of the most important commercial alloys including steel, cast iron, aluminum-silicon eutectics, and superalloys • updated tables of material constants.
Author: A. Roósz
Publisher: Trans Tech Publications Ltd
ISBN: 3038264741
Category : Technology & Engineering
Languages : en
Pages : 540
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Book Description
The results of many foreign and Hungarian researchers presented at the 6th International Conference on Solidification and Gravity, in Miskolc-Lillafüred, on September 2-5, 2013 have been collected in this volume. This conference series is aimed to attract all those having interest in the investigation and simulation of different types of solidification processes and both micro- and macro-gravity effects. Within the framework of the conference a MICAST meeting (Microstructure Formation in Casting of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions) was organized on September 5-6, 2013. The 2013 conference was a memorial one for Professor Hans Eckart Exner and Professor Erik György Fuchs who had died in the period between the previous (2008) and the last (2013) conference.
Author: Laurentiu Nastac
Publisher: Springer
ISBN: 3319651331
Category : Technology & Engineering
Languages : en
Pages : 278
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Book Description
