Grain Boundary Migration in Nanocrystalline Iron
|Tomasz Wejrzanowski , Krzysztof J. Kurzydlowski|
Warsaw University of Technology, Faculty of Materials Science and Engineering (InMat), Wołoska 141, Warszawa 02-507, Poland
The migration of grain boundaries in polycrystalline materials is driven by a reduction of the internal energy. This can be achieved either by decreasing the surface area of grain boundaries or by reducing their specific energy (energy per surface unit). Diffusion controlled reduction of the interface curvature as well as the rotation of grains could be considered, respectively. However, due to the kinetic barriers for rotation of the grains in polycrystalls, this process is not observed in coarse grained materials. However, in nanomaterials it could play an important role in the process of grain growth.
In this study a series of 3D models for curved grain boundaries in pure iron have been built. Each model consisted of a spherical grain, with an initial size of about 9 nm, surrounded by a large single-crystal. Different orientations have been assigned to the grain and the matrix in order to obtain interfaces with misorientation angles in the range of 5-45 degrees in steps of 5 degrees. The molecular dynamics with EAM potential have been performed for investigation of temporal changes in grain boundary migration and rotation. The relation between grain size, grain boundary misorientation has been revealed. It was also found that the density of the material decreases with a reduction of grain boundary area.
The effect of a triple junction on the interface motion has been also studied by introducing a bi-crystal matrix instead of a single-crystal matrix.
The results are discussed in terms of grain growth investigations in nanometals.
Presentation: Poster at E-MRS Fall Meeting 2006, Symposium H, by Tomasz Wejrzanowski
See On-line Journal of E-MRS Fall Meeting 2006
Submitted: 2006-05-12 09:35 Revised: 2009-06-07 00:44