Curvature driven grain boundary migration in aluminum: molecular dynamics simulations

Molecular dynamics simulations have been used to study steady-state, capillarity-driven grain boundary migration in three dimensions for a series of (left angle bracket)1 1 1(right angle bracket)-tilt boundaries in aluminum. The reduced boundary mobility and boundary enthalpy were determined as a function of misorientation and temperature. For the misorientations examined, the reduced mobility is a maximum and the activation energy for migration is a minimum at the (sigma)7 misorientation. The reduced mobility is an Arrhenius function of temperature. Excellent agreement between the present three-dimensional simulation results, those obtained earlier in two dimensions and experiment is obtained for a wide variety of features, with the notable exception of the magnitude of the grain boundary mobility. The mobilities from the simulations are much higher than from experiment; the activation energies for migration are much lower. The present results are intrinsic, while the experimental measurements may be limited by extrinsic factors such as impurity drag.