Papers by Keyword: Grain Growth

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Authors: Yasuhiro Yogo, Kouji Tanaka, Koukichi Nakanishi
Abstract: An in-situ observation method for structures at high temperature is developed. The new observation device can reveal grain boundaries at high temperature and enables dynamic observation of these boundaries. Grain growth while maintaining microstructure at high temperature is observed by the new observation device with only one specimen for the entire observation, and grain sizes are quantified. The quantifying process reveals two advantages particular to the use of the new observation device: (1) the ability to quantify grain sizes of specified sizes and (2) the results of average grain size for many grains have significantly less errors because the initial structure is the same for the entire observation and the quantifying process. The new observation device has the function to deform a specimen while observing structures at high temperature, so that enables it to observe dynamic recrystallization of steel. The possibility to observe recrystallization is also shown.
Authors: C. M. Hefferan, S. F. Li, J. Lind, Ulrich Lienert, Anthony D. Rollett, R.M. Suter
Abstract: We have used high energy x-ray diffraction microscopy (HEDM) to study annealing behavior in high purity aluminum. In-situ measurements were carried out at Sector 1 of the Advanced Photon Source. The microstructure in a small sub-volume of a 1 mm diameter wire was mapped in the as-received state and after two differential anneals. Forward modeling analysis reveals three dimensional grain structures and internal orientation distributions inside grains. The analysis demonstrates increased ordering with annealing as well as persistent low angle internal boundaries. Grains that grow from disordered regions are resolution limited single crystals. Together with this recovery behavior, we observe subtle motions of some grain boundaries due to annealing.
Authors: X. Xue, T.M. Liebling, A. Mocellin
Authors: Morteza Toloui, Matthias Militzer
Abstract: Three dimensional (3D) phase field modelling is used to simulate austenite grain growth in X80 linepipe steel for thermal paths that are typical in the heat affected zone (HAZ). In the HAZ austenite grain growth is affected by pinning due to precipitates and their potential dissolution. Effective grain boundary mobilities are introduced that are consistent with strong pinning at lower temperatures and weak pinning at higher temperatures separated by the estimated dissolution temperature range of fine NbC precipitates. These mobility relationships are then used to describe austenite grain growth in bulk samples subjected to rapid heating and cooling conditions to replicate thermal cycles at various positions in the HAZ.
Authors: Giuseppe Carlo Abbruzzese
Abstract: Based on a 3-D Von Neumann equation a general theoretical formulation has been provided in the framework of the statistical theory of grain growth to predict the microstructure evolution. By the same approach the topological relationships between number of grain faces, grain size, number of corners and edges and how these can be calculated in a real microstructure with a statistical approach are discussed. A quadratic law for the linkage between number of faces and grain size is found and together with the functional dependency of other relevant 3-D microstructure parameters good agreement with available experimental results is found .
Authors: Henning Friis Poulsen, Xing Fu, Erik Knudsen, Erik M. Lauridsen, L. Margulies, S. Schmidt
Abstract: 3-Dimensional X-Ray Diffraction (3DXRD) microscopy is a tool for fast and non-destructive characterization of the individual grains, sub-grains and domains inside bulk materials. The method is based on diffraction with highly penetrating hard x-rays, enabling 3D studies of millimeter - centimeter thick specimens. The position, volume, orientation, elastic and plastic strain can be derived for hundreds of grains simultaneously. Furthermore, by applying novel reconstruction methods 3D maps of the grain boundaries can be generated. With the present 3DXRD microscope set-up at the European Synchrotron Radiation Facility, the spatial resolution is ~ 5 µm, while grains of size 100 nm can be detected. 3DXRD microscopy enables, for the first time, dynamic studies of the individual grains and sub-grains within polycrystalline materials. The methodology is reviewed with emphasis on recent advances in grain mapping. Based on this a series of general 3DXRD approaches are identified for studies of nucleation and growth phenomena such as recovery, recrystallisation and grain growth in metals.
Authors: Anthony D. Rollett
Authors: Atsuto Okamoto, H. Yashiki
Authors: Nele Moelans, Bart Blanpain, Patrick Wollants
Abstract: A phase field model for simulating grain growth and thermal grooving in thin films is presented. Orientation dependence of the surface free energy and misorientation dependence of the grain boundary free energy are included in the model. Moreover, the model can treat different mechanisms for groove formation, namely through volume diffusion, surface diffusion, evaporation-condensation, or a combination of these mechanisms. The evolution of a groove between two grains has been simulated for different surface and grain boundary energies and different groove formation mechanisms.
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