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Autumn 2008 Seminar Series
Monday, October 27, at 3:30 p.m.
Room 264 MacQuigg Labs
Ning Zhou
PhD Candidate advised by Dr. Yunzhi Wang
Department of Material Science and Engineering
The Ohio State University
Simulation Study of Directional Coarsening (Rafting) of Gamma Prime in Single Crystal Ni-Al
Abstract
Three-dimensional phase field modeling of coupled gamma/gamma prime microstructural evolution and plastic deformation was carried at two different length scales. The relative contributions from elastic modulus inhomogeneity and gamma channel plasticity were first quantified by the dislocation-level simulations, which showed that the latter plays the dominant role in controlling the rafting process. Then micrometer-scale simulations were carried out that takes into account plastic deformation in gamma channels described by local channel dislocation densities from individual active slip systems. The rafting kinetics and the corresponding creep deformation were characterized at different values of applied stress, lattice misfit and precipitate volume fraction. The simulation results were compared with available experiment carried out for Ni-Al-Cr and quantitative agreement has been obtained. The models have the ability to make quantitative predictions to gamma prime rafting and the corresponding creep deformation in new superalloys (such as the Co- and Pt-based alloys) that are currently under development.
Bio
Ning Zhou graduated from Shanghai Jiao Tong University (Shanghai, China) with his BachelorÕs and MasterÕs degree in Materials Science and Engineering and joined the Ohio State University in September 2003. He is a member of Dr. Yunzhi WangÕs group, focusing on computer simulation of microstructural and mechanical properties of Ni-Base superalloys using phase field method.
