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Topic: Multiscale Phase Field Modeling of Phase Transformation and Plastic Deformation
Abstract
Based on gradient thermodynamics, Green function solution of long-range elastic interactions, and field representation of microstructures, the phase field method has received much attention lately as a quantitative technique to model complex morphological patterns formed during many materials processes including phase transformation, grain growth, sintering, interdiffusion, and plastic deformation. It accounts self-consistently for high volume fraction of precipitates, multiple anti-phase domains and orientation variants, dislocation core structures, shape anisotropy and spatial alignment induced by long-range elastic interactions, and complicated topological changes. Recently, a new microscopic phase field (MPF) model of precipitate-dislocation interactions was developed by using arbitrary inelastic strain fields and generalized stacking fault (GSF) energy. With ab initio calculations of GSF energy as model input, the MPF model has been shown quantitatively to be a 3D generalization of the Peierls-Nabarro model.
In this presentation we discuss formulations and applications of the method in modeling microstructure evolution during precipitation and plastic deformation. Examples are chosen to illustrate the capabilities of the method at both mesoscopic and microscopic length scales. At the mesoscopic level we present simulation predictions of various g/g?/SPAN> microstructures in Ni-base superalloys and a/b microstructures in Ti-alloys, with particular emphasis on the spatial variation, correlation and anisotropy of the microstructures. Recent investigations of creep deformation of Ni-base superalloys and a/b Ti-alloys demonstrate clearly the importance of detailed microstructural features in determining dislocation-precipitate interactions and the corresponding kinetic pathways of the deformation process. Many new dislocation processes beyond the conventional bypass and cutting mechanisms have been observed. We illustrate the unique opportunities offered by the MPF model to treat complex dislocation-microstructure interactions in these alloys without any a priori assumptions about dislocation geometry, core structure, and formation of stacking faults. In combination with the nudged elastic band method, the minimum energy path, activation energy and critical nucleus configuration during phase transformations and plastic deformation are characterized.
CURRICULUM VITAE--Yunzhi Wang
BIOGRAPHICAL SKETCH: YUNZHI WANG
Professional Preparation
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INSTITUTION AND LOCATION |
MAJOR |
DEGREE/YR |
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Rutgers, The State University of New Jersey,New Brunswick,NJ |
Materials Science and Engineering |
M.S. 1992 |
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Rutgers, The State University of New Jersey, New Brunswick,NJ |
Materials Science and Engineering |
Ph.D. 1995 |
Appointments
2005- Professor, Ohio State Univ. Department of Materials Science and Engr.
2002-05 Associate Professor, Ohio State Univ. Department of Materials Science and Engr.
1996-02 State Univ. Department of Materials Science and Engr.
1995-96 Postdoctoral Associate, The State , Dept. of Ceramics
Awards and Honors
2005 KC Wong Research Award (K.C.Wong Education Foundation, )
2003 Senior Visiting Research Fellow, Research, of Science
2001 Lumley Research Award from State University
1997 Career Award, National Science Foundation.
1993 Hoechst Celanese Graduate Excellence Award (Hoechst Celanese Corporation and )
Closely-Related Publications
1. C. Shen and Y. Wang, “Incorporation of g-Surface to Phase Field Model of Dislocations: Simulating Dissociation of Dislocations in f.c.c. ,” Acta mater. 52:683-691 (2004).
2. C. Shen and Y. Wang, “Phase Field Model of Dislocation Networks,” Acta mater. 51, 2595 – 2610 (2003).
3. Y. Wang, D. Banerjee, C. C. Su and A. G. Khachaturyan, “Field Kinetic Model and Computer Simulation of Precipitation of L12 ordered Intermetallic from FCC Solid Solution, Acta Mater, 46, 2983-3001 (1998).
4. K. Wu, Y. A. Chang and Y. Wang, “Simulating Interdiffusion Microstructure in Ni-Al-Cr Diffusion Couples: A Phase Field Approach Coupled with CALPHAD Database,” submitted to Scripta mater. (2003).
5. N. Ma, A. Kazaryan, S. A. Dregia and Y. Wang, “Texture Development during Grain Growth in Systems of Anisotropic Energy and Mobility,” Acta mater. 52:3869-3879 (2004).
Other Significant Publications
1. K. Wu, J. E. Morral and Y. Wang, “Movement of Kirkendall Markers, Second Phase Particles and Type 0 Boundary in Two-Phase Diffusion Couple Simulations,” Acta mater. 52:1917-1925 (2004).
2. N. Ma, S. A. Dregia and Y. Wang, “Segregation Transition and Drag Force at Grain Boundaries,” Acta mater. 51, 3687-3700 (2003).
3. A. Kazaryan, Y. Wang, S. A. Dregia and B. R. Patton, “Grain Growth in Anisotropic Systems: Comparison of Effect of Energy and Mobility,” Acta mater. 50, 2491-2502 (2002).
4. Y. Wang and A. G. Khachaturyan, "Three-Dimensional Field Model and Computer Modeling of Martensitic Transformation", Acta Metall. et Mater , 45, 759 (1997).
5. Y. Wang, L. Q. Chen and A. G. Khachaturyan, "Kinetics of Strain-Induced Morphological Transformation in Cubic Alloys with a Miscibility Gap", Acta Metall. et Mater., 41, 279 (1993)
Synergistic Activities
Significant cost savings can be realized in alloy design and processing by using computer modeling, reducing the amount of experimental effort necessary. Wang’s research projects focus on the development of computational models and simulation techniques, validated by experimentation, for microstructural engineering of advanced materials. He is currently leading the computational efforts at the Center for Accelerated Maturation of Materials at the to develop new methodology for accelerated maturation of high performance structural materials.
His work ties closely to the University’s newly established research and education thrust on computational materials science and engineering. He and his colleagues have developed and taught new courses on Computational Modeling in Materials Science and Engineering at both undergraduate and graduate level and simplified versions of software packages developed in the research projects have been adopted in these courses.
Collaborators and Other Affiliations
(a) Collaborators: Long-Qing Chen, Penn. State University; Armen Khachaturyan, Rutgers Univ.; Austin Chang, Univ. of Wisconsin; David Laughlin, Carnegie Mellon Univ.; Jeff P. Simmons, Air Force Research Laboratory, AFL/MLLM, Wright-Patterson AFB; John E. Morral, Ohio State Univ.; Suliman A. Dregia, Ohio State Univ.; Hamish L. Fraser, Ohio State Univ.; Mike J. Mills, Ohio State Univ.
(b) Graduate Student/Postdoctoral Advisors: Armen Khachaturyan,Rutgers
(c) Thesis Advisor and Postgraduate-Scholar Sponsor: Yuhui Liu (MS). Dipanwita Banerjee (MS), Andrei Kazaryan (Ph.D), Kaisheng Wu (Ph.D), (Ph.D and postdoc), Ning Ma (Ph.D and postdoc), Rajarshi Banerjee (postdoc), Yuhai Wen (postdoc), Qing Chen (postdoc).
Number of graduate students currently advised: 4
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