Berlin 2012 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 60: Computational Materials Modelling IX - Interfaces and Boundaries

MM 60.4: Talk

Thursday, March 29, 2012, 18:00–18:15, TC 006

Simulations of grain boundary migration via the nucleation and growth of islands — •Christopher Race, Johann von Pezold, and Joerg Neugebauer — Max-Planck-Institut fuer Eisenforschung, Duesseldorf, Deutschland

Classical molecular dynamics simulations of bicrystals have been much used to explore the motion of grain boundaries. Commonly, previous studies were designed to explore the large configurational space of possible grain boundary structures and so necessarily employed small simulation cells. In such small cells the whole area of the grain boundary is constrained to move simultaneously and so the boundary remains atomically flat. The formation of important features such as double kinks and islands is often absent.

We have therefore studied the motion of a symmetric tilt boundary in system sizes large enough to accommodate the nucleation and growth of stable islands of migrated crystal volume. We consider the effect of the driving force for grain boundary motion on the size of a critical island nucleus and on the energy barrier for its formation. Based on our results we identify two distinct regimes of mesoscale migration mechanism (island-based vs. flat) in terms of driving force and system size. We consider the implications of this insight for the interpretation of results of typical grain boundary simulations.