Thermodynamics of grain boundary premelting in alloys. II. Atomistic simulation

We apply the semi-grand-canonical Monte Carlo method with an embedded-atom potential to Study grain boundary (GB) premelting in Cu-rich Cu-Ag alloys. The Sigma 5 GB chosen for this study becomes increasingly disordered near the solidus line while its local chemical composition approaches the liquidus composition at the same temperature. This behavior indicates the formation of a thin layer of the liquid phase in the GB when the grain composition approaches the solidus. The thickness of the liquid layer remains finite and the GB can be overheated/oversaturated to metastable states slightly above the solidus. The premelting behavior found by the simulations is qualitatively consistent with the phase-field model of the same binary system presented in Part I of this work [Mishin Y, Boettinger WJ, Warren JA, McFadden GB. Acta Mater, in press]. Although this agreement is encouraging, we discuss several problems arising when atomistic simulations are compared with phase-field modeling. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.