Survey of computed grain boundary properties in face-centered cubic metals-II: Grain boundary mobility

The absolute grain boundary mobility of 388 nickel grain boundaries was calculated using a synthetic driving force molecular dynamics method; complete results appear in the supplementary materials. Over 255 of the boundaries, including most of the non-Sigma 3 highest mobility boundaries, moved by a coupled shear mechanism. The range of non-shearing boundary mobilities is from 40 to 400 m/s GPa. except for Sigma 3 incoherent twins which have mobilities of 200-2000 m/s GPa. Some boundaries, including all the < 1 1 1 > twist boundaries, are immobile within the resolution of the simulation. Boundary mobility is not correlated with scalar parameters such as disorientation angle. Sigma value, excess volume or boundary energy. Boundaries less than 15 degrees from each other in five-dimensional crystallographic space tend to have similar mobilities. Some boundaries move via a non-activated motion mechanism, which greatly increases low-temperature mobility. Thermal roughening of grain boundaries is widely observed, with estimated roughening temperatures substantially among boundaries. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.