Atomistic simulations were made of segregation to a dissociated a/2[11¯0] edge dislocation in a Ni0.9Cu0.1 solid solution alloy. Segregation to the stacking fault between the partials was minimal. It was found that the results which were obtained by using a general embedded atom method potential, or one which was optimum for this alloy system, differed significantly. The simulations which involved the use of optimized potentials indicated the occurrence of significantly more Cu segregation to the dislocation cores than did the simulations which were performed using general potentials. When the general potentials were used, the Cu concentration around the dislocation was well-described by using classical segregation isotherms that were based upon the stress distribution around the dislocation; except in the dislocation core region. The deviations from the theoretically predicted segregation profile around the dislocation core were largest along the slip plane. When the optimum potentials were used, the deviations from the predicted segregation behavior were significantly greater. The large deviations that were associated with the optimum potentials were traced to an inadequate description of the local heat of segregation in terms of the elastic work. This could be rectified by adding a term, to the heat of segregation, that explicitly included the compositional dependence. The failure of the classical segregation isotherm to describe the segregation behavior around a dislocation was associated with non-ideal alloy thermodynamics and with the inadequacy of linear elasticity for describing the core region of the dislocation. The failure of the classical segregation isotherm within the core appeared to result from the fact that the core atoms had a different atomic coordination to those in the bulk material.

R.W.Smith, R.Najafabadi, D.J.Srolovitz: Acta Metallurgica et Materialia, 1995, 43[10], 3621-32