Comparison of Experimental and Computational Aspects of Grain Growth in Al-Foil
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Comparison of Experimental and Computational Aspects of Grain Growth in Al-Foil Melik C. Demirel1, Andrew P. Kuprat2, Denise C. George2, Bassem S. El-Dasher1, Neil N. Carlson3, Galen K. Straub2, and Anthony D. Rollett1 1
Carnegie Mellon University, Materials Science & Engineering, PA, USA Theoretical Division, T-1, Los Alamos National Laboratory, NM, USA 3 Computational Materials Group, DigitalDNA Laboratories, Motorola, NM, USA 2
ABSTRACT Grain boundary and crystallographic orientation information of an Al-foil with a columnar grain structure is characterized by Electron Backscattered Diffraction (EBSD) technique. The starting microstructure and grain boundary properties are implemented as an input for the threedimensional grain growth simulation. In the computational model, minimization of the interface energy is the driving force for the grain boundary motion. The computed evolved microstructure is compared with the final experimental microstructure, after annealing at 550 ºC. Good agreement is observed between the experimentally obtained microstructure and the simulated microstructure. The constitutive description of the grain boundary properties was based on a 1parameter characterization of the variation in mobility with misorientation angle. INTRODUCTION Grain boundary mobility varies by several orders of magnitude depending on the grain boundary misorientation and inclination. Grain boundary energy and mobility can be extracted with the measurement of the geometry of triple junctions between grain boundaries [1]. These experimental results on grain boundary properties that are obtained from EBSD technique can be used to simulate the topological changes in grain boundary motion. Simulation [2, 3], theory [4], and the experimental observation [5] of grain boundary evolution of three-dimensional microstructures have been studied by several authors in the literature. A new technique for three-dimensional grain growth simulations was introduced by Kuprat [6]; this method utilizes gradient-weighted moving finite elements (GWMFE) [7] combined with algorithms for performing topological reconnections on the evolving mesh [8]. In this model, minimization of the interface energy is the main driving force for the grain boundary motion. Interface motion is assumed to obey a linear equation (v=µκ) where µ is reduced mobility, v is the velocity, and κ is the curvature of the grain boundary. An important verification of the model is that the expected power law dependence of growth kinetics is obtained [9]. The gradient in mobility has a major effect on the growth process. In this paper, the orientation dependence of the boundary mobility is introduced in order to break the symmetry in GWMFE simulations. With the same simulation technique, both normal and abnormal grain growth in three-dimensions can be studied. In the following section, a brief summary of experimental details is presented. This is followed by results from GWMFE simulation, then comparison with annealing experiment, and ending with a discussion and conclusi
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