Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Phase Field Simulation on Microstructure Evolution in Solidification and Aging Process of Squeeze Cast Magnesium Alloy
Author: Modeling and Simulation of Microstructure Evolution in Solidifying Alloys
Author: Laurentiu NastacPublisher: Springer Science & Business Media
ISBN: 1402078315
Category : Technology & Engineering
Languages : en
Pages : 298
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.
Quantitative Phase Field Modelling of Solidification
Author: Nikolas ProvatasPublisher: CRC Press
ISBN: 1000435008
Category : Science
Languages : en
Pages : 186
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
Phase Field Based Study of Microstructure Evolution in Solidification of Mo-rich Mo-Si-B Alloys
Author: Omid KazemiAdvances in the Science and Engineering of Casting Solidification
Author: Laurentiu NastacPublisher: Springer
ISBN: 3319481177
Category : Technology & Engineering
Languages : en
Pages : 419
Book Description
This collection encompasses the following four areas: (1) Solidification processing: theoretical and experimental investigations of solidification processes including castings solidification, directional solidification of alloys, electromagnetic stirring, ultrasonic cavitation, mechanical vibration, active cooling and heating, powder bed-electron beam melting additive manufacturing, etc. for processing of metals, polymers and composite materials; (2) Microstructure Evolution: theoretical and experimental studies related to microstructure evolution of materials including prediction of solidification-related defects and particle pushing/engulfment aspects; (3) Novel Casting and Molding Processes: modeling and experimental aspects including high pressure die casting, permanent casting, centrifugal casting, low pressure casting, 3D silica sand mold printing, etc.; and (4) Cast Iron: all aspects related to cast iron characterization, computational and analytical modeling, and processing.
Fundamental and Practical Applications of Phase Field Method to the Study of Alloy Microstructure Evolutions
Author: Weiqi LuoPublisher:
ISBN:
Category : Microstructure
Languages : en
Pages : 206
Book Description
Abstract: The microstructure of a material has a great influence on its properties. Therefore, understanding underlying mechanisms of microstructural evolution is critical for developing desired properties. However, microstructural evolution is highly non-linear and, at this stage, fundamental quantitative understanding of it is limited. There has been an increasing demand lately for modeling and simulating microstructural evolution. That is not only because they have a relatively lower cost than experiment, and can be performed for arbitraries conditions, but also they can provide fundamental understanding of experimental observations, and its ability to predict the evolution. Moreover, a quantitative predictive model will be very usefully to guide process design in various industry applications. For this reason, many computer models have been developed. Among them, the phase field method has become a rigorous approach to simulating complex microstructural evolution, such as martensitic transformation, dendritic growth, dislocation movement and grain growth. The effect of nucleating ordered precipitates at dislocations and the subsequent growth on particle morphology in Ni-Al and Al-Li through phase field method study is presented in this thesis. Results show that this process yields the splitting pattern that is observed experimentally. In particular, the structural discontinuity associated with an edge dislocation may lead to the formation of an antiphase domain boundary within an ordered phase particle. At this stage, the application of phase field methods in industry is still limited because many phase field models are qualitative in nature. The development of a quantitative phase field model for the Fe-Cr-C system by designing an appropriate energy expression and linking the thermodynamic and kinetics parameters to quantitative databases is presented in this thesis. This model is validated and its capability is shown in the corresponding chapter.
Phase-field simulations of multi-component solidification and coarsening based on thermodynamic datasets
Author: Schulz, SebastianPublisher: KIT Scientific Publishing
ISBN: 3731506181
Category : Aluminum
Languages : en
Pages : 246
Book Description
The utilization of thermodynamic and mobility data plays a major role in phase-field modeling. This work discusses different formulations for the thermodynamic quantities of a grand potential model along with practices to determine parameters from datasets. The framework is used to study solidification of Al-Si-Mg for a variation of composition, diffusivities and surface energy anisotropies. To verify the simulations, they are compared with solidification theories.
Phase-field Simulation of Microstructural Development Induced by Interdiffusion Fluxes Under Multiple Gradients
Author: Rashmi Ranjan MohantyPublisher:
ISBN:
Category : Diffusion
Languages : en
Pages : 225
Book Description
The diffuse-interface phase-field model is a powerful method to simulate and predict mesoscale microstructure evolution in materials using fundamental properties of thermodynamics and kinetics. The objective of this dissertation is to develop phase-field model for simulation and prediction of interdiffusion behavior and evolution of microstructure in multi-phase binary and ternary systems under composition and/or temperature gradients. Simulations were carried out with emphasis on multicomponent diffusional interactions in single-phase system, and microstructure evolution in multiphase systems using thermodynamics and kinetics of real systems such as Ni-Al and Ni-Cr-Al. In addition, selected experimental studies were carried out to examine interdiffusion and microstructure evolution in Ni-Cr-Al and Fe-Ni-Al alloys at 1000°C. Based on Onsager's formalism, a phase-field model was developed for the first time to simulate the diffusion process under an applied temperature gradient (i.e., thermotransport) in single- and two-phase binary alloys. Development of concentration profiles with uphill diffusion and the occurrence of zero-flux planes were studied in single-phase diffusion couples using a regular solution model for a hypothetical ternary system. Zero-flux plane for a component was observed to develop for diffusion couples at the composition that corresponds to the activity of that component in one of the terminal alloys. Morphological evolution of interphase boundary in solid-to-solid two-phase diffusion couples (fcc-[gamma] vs. B2-[beta]) was examined in Ni-Cr-Al system with actual thermodynamic data and concentration dependent chemical mobility. With the instability introduced as a small initial compositional fluctuation at the interphase boundary, the evolution of the interface morphology was found to vary largely as a function of terminal alloys and related composition-dependent chemical mobility. In a binary Ni-Al system, multiphase diffusion couples of fcc-[gamma] vs. L12-[gamma prime], [gamma] vs. [gamma]+[gamma prime] and [gamma]+[gamma prime] vs. [gamma]+[gamma prime] were simulated with alloys of varying compositions and volume fractions of second phase (i.e., [gamma prime]). Chemical mobility as a function of composition was employed in the study with constant gradient energy coefficient, and their effects on the final interdiffusion microstructure was examined. Interdiffusion microstructure was characterized by the type of boundaries formed, i.e. Type 0, Type I, and Type II boundaries, following various experimental observations in literature and thermodynamic considerations. Volume fraction profiles of alloy phases present in the diffusion couples were measured to quantitatively analyze the formation or dissolution of phases across the boundaries. Kinetics of dissolution of [gamma prime] phase was found to be a function of interdiffusion coefficients that can vary with composition and temperature. The evolution of interdiffusion microstructures in ternary Ni-Cr-Al solid-to-solid diffusion couples containing fcc-[gamma] and [gamma]+[beta] (fcc+B2) alloys was studied using a 2D phase-field model. Alloys of varying compositions and volume fractions of the second phase ([beta]) were used to simulate the dissolution kinetics of the [beta] phase. Semi-implicit Fourier-spectral method was used to solve the governing equations with chemical mobility as a function of compositions. The simulation results showed that the rate of dissolution of the [beta] phase (i.e., recession of [beta]+[gamma] two-phase region) was dependent on the composition of the single-phase [gamma] alloy and the volume fraction of the [beta] phase in the two-phase alloy of the couple. Higher Cr and Al content in the [gamma] alloy and higher volume fraction of [beta] in the [gamma]+[beta] alloy lower the rate of dissolution. Simulated results were found to be in good agreement with the experimental observations in ternary Ni-Cr-Al solid-to-solid diffusion couples containing [gamma] and [gamma]+[beta] alloys. For the first time, a phase-field model was developed to simulate the diffusion process under an applied temperature gradient (i.e., thermotransport) in multiphase binary alloys. Starting from the phenomenological description of Onsager's formalism, the field kinetic equations are derived and applied to single-phase and two-phase binary system. Simulation results show that a concentration gradient develops due to preferential movement of atoms towards the cold and hot end of an initially homogeneous single-phase binary alloy subjected to a temperature gradient. The temperature gradient causes the redistribution of both constituents and phases in the two-phase binary alloy. The direction of movement of elements depends on their atomic mobility and heat of transport values.
Quantitative Phase-field Model for Phase Transformations in Multi-component Alloys
Author: Abhik Narayan ChoudhuryPublisher: Karlsruher Institut Fur Technologie
ISBN: 9783731500209
Category : Physics
Languages : en
Pages : 0
Book Description
Phase-field modeling has spread to a variety of applications involving phase transformations.While the method has wide applicability, derivation of quantitative predictions requires deeper understanding of the coupling between the system and model parameters. The book highlights a novel phase-field model based on a grand-potential formalism allowing for an elegant and efficient solution to problems in phase transformations.
Phase-field modeling of microstructural pattern formation in alloys and geological veins
Author: Ankit, KumarPublisher: KIT Scientific Publishing
ISBN: 373150491X
Category : Technology (General)
Languages : en
Pages : 240
Book Description
With the advent of high performance computing, the application areas of the phase-field method, traditionally used to numerically model the phase transformation in metals and alloys, have now spanned into geoscience. A systematic investigation of the two distinct scientific problems in consideration suggest a strong influence of interfacial energy on the natural and induced pattern formation in diffusion-controlled regime.