Detailed analysis of the segregation driving forces for Ni(Ag) and Ag(Ni) in the Σ=11{113} and Σ=11{332} grain boundaries

The behaviour with respect to segregation is studied for two qualitatively different symmetrical tilt grain boundaries (GBs): a low energy boundary with mirror-symmetric structure on the {1 1 3} plane and the high energy {3 3 2} GB with a zigzag structural pattern. These two structures have been confirmed by high resolution transmission electronic microscopy observations in nickel. Intergranular segregation is studied in the limit of infinitely diluted solution for Ni(Ag) and Ag(Ni) systems modelled with Finnis-Sinclair like potentials. The atomic sites are characterized by a geometrical parameter defined by their exact Voronoy volumes and the pressure locally exerted. The segregation energies and driving forces are compared with these parameters in order to characterize a segregation susceptibility of intergranular atomic sites. The size effect calculated by the method of virtual impurity represents the main segregation driving force for the considered systems. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.