Papers by Keyword: Phase Field Modellig

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Authors: M.Y. Wang, T. Jing
Abstract: A new algorithm of phase field model is developed to simulate polycrystalline dendritic solidification growth in undercooled melts. The algorithm adopts a single phase field order parameter model incorporated with the anisotropy of solid-liquid interfacial energy and mobility. The model validation is performed by comparing the simulations with the theory analytical results and experimental information for both single and multi-grain dendritic growth, which demonstrates the quantitative capabilities of the proposed algorithm.
Authors: Dong Hee Yeon, Pil Ryung Cha, Jong Kyu Yoon
Authors: Richard G. Thiessen, Jilt Sietsma, I.M. Richardson
Abstract: This work presents a unique approach for the modelling of the austenitisation of martensite in dual-phase steels within the phase-field method. Driving forces for nucleation and growth are derived from thermodynamic databases. Routines for nucleation are based on a discretisation of the classical nucleation theory. Validation is given via dilatometric experiments.
Authors: Seong Gyoon Kim, Won Tae Kim, Yong Bum Park
Abstract: Abnormal grain growth (AGG) proceeds in case that normal grain growth is inhibited. It has long been known that the inhibition involves finely dispersed particles and/or the development of specific textures. There is another strong obstacle against the grain boundary (GB) motion; the solute atoms can reduce their energy by moving from the bulk into a GB. Resultant interaction between the solute atoms and a GB makes the GB motion more difficult. However the role of the GB segregation effect on AGG has not been clarified. In this study we simulate the 2D and 3D grain growth accompanying boundary segregation of solute atoms by using a phase-field model. It is shown that the segregation plays an important role on the occurrence of AGG. The boundary-segregation-induced AGG can take place when the average driving force of grain growth approaches a critical condition for pinning-depinning transition in solute-drag atmosphere.
Authors: Kyung Jun Ko, Pil Ryung Cha, Jong Tae Park, Jae Kwan Kim, Nong Moon Hwang
Abstract: Abnormal grain growth (AGG) takes place in many metallic systems especially after recrystallization of deformed polycrystals. A famous example of AGG in metallic system is the Goss texture in Fe-3%Si steel. During high temperature annealing of Fe-3%Si sheet, a few near Goss {110} <001> grains grow exclusively fast and consume the matrix grains. Therefore, the grains which have near Goss orientation have special advantage over other grains. As a new approach to the growth advantage of AGG, we suggested the solid-state wetting mechanism, where a grain wets or penetrates the grain boundary or the triple junction of its neighboring grains. The solid-state wetting mechanism for the evolution of the Goss texture in Fe-3%Si steel was studied experimentally and by phase-field model (PFM) simulation.
Authors: Bruno C. De Cooman, H.K.D.H. Bhadeshia, Frédéric Barlat
Abstract: The present contribution highlights the approach to multi-scale steel design used at the Graduate Institute of Ferrous Technology (GIFT). Multi-scale modeling combining ab-initio methods, molecular dynamics, crystal plasticity modeling etc. enables GIFT researchers to gain a better fundamental understanding of phase and lattice stability, magnetic properties and basic mechanical constants. In addition, these methods allow for the reliable determination of critical material parameters. The opportunities for the development of new steel grade is thereby greatly enhanced and, when these new materials-oriented methods are combined with the more traditional engineering modeling methods, the challenges related to the large scale production of new steel grades can also be addressed.
Authors: Yoshihiro Suwa, Yoshiyuki Saito, Hidehiro Onodera
Abstract: The kinetics and topology of grain growth in three dimensions were simulated using a phase-field model with anisotropic grain-boundary mobilities. In order to perform large scale calculations we applied both modifications of algorithms and parallel coding techniques to the Fan and Chen's phase-field algorithm. Kinetics of abnormal grain growth is presented. It is observed that the grains of a minor component which are at the beginning surrounded preferentially by boundaries of high mobility grow faster than the grains of a major component until the texture reverses completely. Additionally, topological results of grain structures, such as grain size distributions and grain face distributions, are discussed
Authors: D.J. Seol, S.Y. Hu, Yong Li Li, Li Qing Chen, Kyu Hwan Oh
Authors: Dong Uk Kim, Seong Gyoon Kim, Won Tae Kim, Jae Hyung Cho, Heung Nam Han, Pil Ryung Cha
Abstract: In this presentation, a novel phase field grain growth model combined with a micro-elasticity effect including elastic anisotropy and inhomogeity is presented to demonstrate the effect of micro-elasticity on grain growth and texture evolution. We report on texture evolution and abnormal grain growth induced by external elastic load from the viewpoint of micro-elasticity and first demonstrate that the previous mechanism (macroscopic viewpoint) on the effect of external elastic load on grain growth does not work in strain-controlled system. In contrast to the macro-elastic descriptions, strong localization of strain energy density and inhomogeneous distribution even inside grains are observed. Moreover, elastically soft grains with a higher strain energy density grow at the expense of the elastically hard grains to reduce the total strain energy. It is observed that strong <100>//ND fiber texture was developed in poly-crystalline Cu with initial random texture by biaxial external strain while <111>//ND fiber texture evolved in biaxial external stress condition. Even, grain growth of <100>//ND textured grains is occurred as abnormal grain growth when <100>//ND textured grains are surrounded by <111>//ND fiber textured grains.
Authors: M. Asle-Zaeem, S. D. Mesarovic
Abstract: Cahn-Hilliard type of phase field model coupled with elasticity is used to derive governing equations for the stress-mediated diffusion and phase transformation in thin films. To solve the resulting equations, a finite element (FE) model is presented. The partial differential equations governing diffusion and mechanical equilibrium are of different orders; Mixed-order finite elements, with C0 interpolation functions for displacement, and C1 interpolation functions for concentration are implemented. To validate this new numerical solver for such coupled problems, we test our implementation on thin film diffusion couples.
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