Regensburg 2007 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 10: Growth processes and surface properties
DY 10.1: Vortrag
Montag, 26. März 2007, 16:30–16:45, H5
Phase Field Crystal Modeling of Dry and Wet Grain Boundaries — •Jesper Mellenthin1, Alain Karma2, and Mathis Plapp1 — 1Laboratoire de Physique de la Matière Condensée, École Polytechnique, 91128 Palaiseau, France — 2Physics Department, Northeastern University, Boston, MA 02115 USA
The phase field crystal model has emerged as a powerful tool to simulate microstructural evolution in polycrystalline materials under a variety of nonequilibrium conditions. The crystal is represented by a local-time-averaged density field ψ(r→,t), which has the same symmetry as the crystalline structure. This density field is obtained by minimizing a free energy functional, which also allows for a second phase of constant ψ (a liquid phase) and coexistence between the two phases. The model naturally includes the elastic energy and the symmetry properties of the crystal and is therefore a convenient choice to investigate grain boundary properties.
In this work, we explore the influence of the misorientation between two crystals on the grain boundary structure. Dry grain boundaries become wet when the misorientation exceeds some threshold, in which case it becomes energetically favorable for a thin liquid film to exist between the two crystals. This produces an effective repulsion between the two solid-liquid interfaces that coalesce at a temperature below the normal melting point of a bulk crystal. Wet and dry grain boundaries are analyzed numerically and interpreted in the framework of phenomenological models for grain boundary structure.