Research Direction |
A short movie illustrating 2D grain growth: Potts model simulation on a 200x200 grid. |
Current Projects |
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The relationship between materials structure, or microstructure, and the properties of materials continues to stimulate the curiosity of materials scientists. Our research focuses on the relationship of mechanical and magnetic properties to microstructure and the development of tools for quantitative understanding. There are many unresolved issues in microstructural evolution, such as how to make quantitative predictions of texture development during plastic deformation and subsequent annealing. The "abnormal" growth of certain types of grains at the expense of others clearly depends on the properties of the grain boundaries and on the driving forces for growth. Measurement of the grain boundary properties over the entire range of crystallographic types provides one key input to the problem. Understanding the effect of (anisotropic) grain boundary properties on microstructural evolution (grain growth, recrystallization) with Monte Carlo and cellular automata provides another essential part of the puzzle. Simulation and characterization of plastically deformed microstructures provides yet another part of the picture. Since texture, i.e. crystallographic preferred orientation, plays a dominant role in determining the anisotropy of a material,it is also important to verify the relationships. The spatial arrangement of orientations has recently been shown to interact strongly with the development of non-uniform plastic flow or localizations. Also, there many opportunities for optimization of texture for mechanical and magnetic properties, e.g. in laminations for electrical motors. The combination of advanced characterization tools and simulation techniques therefore provides an exciting approach to engineering the anisotropy of materials for optimum properties and performance. |
1. Development of realistic 3D microstructures in aluminum alloys and other materials based on EBSD maps (2D plane sections). Modeling of microstructural evolution based on the generated microstructures for prediction of microstructure and texture development. Extension to 2-phase materials.
2. Development of a coupled grain growth with solute diffusion model that can simulate grain growth, solute diffusion, solute segregation (to boundaries) and solute gradient forces on boundaries; collaboration with Andrew Kuprat (PNL). 3. Development of a parallel Monte Carlo code for large scale simulation of grain growth and recrystallization, including crystallographic texture and anisotropic grain boundary properties; collaboration with Mark Miodownik (Kings College, London) and Elizabeth Holm (Sandia Labs.). 4. Characterization of grain boundary pinning in superalloys and prediction of limiting grain sizes; collaboration with Lee Semiatin (Air Force Research Lab.). 5. Characterization of dislocation structures in moderately deformed metals and their interaction with grain boundaries; collaboration with Prof. Amit Acharya. 6. Measurement of grain boundary properties in iron and characterization of abnormal grain growth in Fe-1%Si. 7. Recrystallization texture and microstructure development in rolled and drawn fcc metals. Orientation selection during grain growth and recrystallization - collaboration with Prof. P. Kalu, FAMU-FSU, Tallahassee, FL. 8. Process modeling of rod and wire rolling of steel under dynamic deformation conditions - collaboration with Prof. P. Manohar, Robert Morris Univ., Pittsburgh, PA. 9. Characterization of full 5-parameter grain boundary distribution in a grain boundary engineered nickel alloy and its relationship to creep properties. 10. Minimization of annealing times in aluminum alloys through characterization and control of recrystallization kinetics as a function of texture - PhD theses by M.J. Alvi and A. Brahme completed as of Sept. 2005. 11. Characterization of stored energy of deformation in aluminum alloys and determination of grain boundary mobility - first PhD thesis by M.L. Taheri completed August 2005. 12. Analysis of plastic deformation in columnar structure tensile samples of heavy metals for validation of large scale simulations of deformation including crystal plasticity - PhD thesis by B. El Dasher completed 2003. |
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Updated 2nd October 2005 |
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