Dresden 2006 – wissenschaftliches Programm

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MM: Metall- und Materialphysik

MM 9: Interfaces

MM 9.1: Vortrag

Montag, 27. März 2006, 14:45–15:00, IFW D

Ab-initio based multiscale calculations of low-angle grain boundaries in Aluminum. — •Liverios Lymperakis and Jörg Neugebauer — Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf

It is commonly accepted that grain boundaries have a central role in grain growth and recrystallization, and have significant contribution to the physical and mechanical properties of materials. A major challenge in describing extended defects such as low-angle grain boundaries is the large range of different length scales: The boundary consists of an array of dislocations where the core structure of each dislocation is rather localized, while the strain field is long range. In a previous study we have developed an ab-initio based multiscale approach that combines elements of density functional theory (DFT), empirical potentials, and continuum elasticity theory[1]. In the present study we have extended the formalism to an infinite array of ordered dislocations as realized in a low angle grain boundary. Based on this approach we have derived a diagram which predicts the energetically most stable boundary as function of the misorientation angle, the relevant displacement between the two grains, and the boundary-boundary separation distance. Based on this diagram we address the issue of grain boundary stability and we discuss recent experimental results.

[1] Phys. Rev. Lett. 93, 196401 (2004).