The spectrum of binding energies approach to grain boundary segregation

Abstract

Experimental data on the temperature dependence of solute segregation to grain boundaries in polycrystalline metals does not appear to be adequately explained by a single binding energy between solute atoms and grain boundary sites. The extent of segregation in a given alloy appears to decrease more slowly with increasing temperature than is consistent with a theory based on such a single binding energy. This behavior can be explained however, if a spectrum of binding energies is assumed to exist. Such a binding energy spectrum presumably results from the site-to-site variation in the solute environment at the grain boundary. The present paper considers the elastic interaction between solute atoms and tilt boundaries in order to estimate the spectrum of binding energies for such boundaries. The extent of solute segregation to these boundaries is then calculated for several sets of parameters that determine the nature of the solute and the grain boundary.