Misorientation dependence of intrinsic grain boundary mobility: Simulation and experiment

Both experimental and atomistic simulation measurements of grain boundary mobility were made as a function of temperature and boundary misorientation using the same geometry that ensures steady-state, curvature-driven boundary migration. Molecular dynamics simulations are performed using: Lennard-Jones potentials on a triangular lattice. These simulations represent the first systematic study of the dependence of intrinsic grain boundary mobility on misorientation. The experiments focus on high purity Al, with [111] tilt boundaries, which are isomorphic to those examined in the simulations. Excellent agreement between simulations and experiments was obtained in almost all aspects of these studies. The boundary velocity is found to be a linear function of the curvature and the mobility is observed to be an Arrhenius function of temperature, as expected. The activation energies for boundary migration varies with misorientation by more than 40% in the simulations and 50% in the experiments. In both the simulations and experiments, the activation energies and the logarithm of the pre-exponential factor in the mobility exhibited very similar variations with misorientation, including the presence of distinct cusps at low Sigma misorientations. The activation energy for boundary migration is a logarithmic function of the pre-exponential factor in the mobility, within a small misorientation range around low Sigma misorientations. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.