On the segregation behavior of tin and antimony at grain boundaries of polycrystalline bcc iron

The study of the temperature dependence of tin and antimony segregation at grain boundaries of binary Fe-Sb and Fe-Sn polycrystalline alloys using Auger Electron Spectroscopy suggests that during the brittle intergranular fracture mainly the general grain boundaries are opened in the samples annealed at low temperatures which are more segregated than the special ones. On the contrary, the special grain boundaries are opened in the samples annealed at higher temperatures because - as a consequence of the enthalpy-entropy compensation effect - they are more enriched by the solute. The limiting temperature between these two states is the so-called compensation temperature. Therefore, the temperature dependence of the grain boundary segregation measured in polycrystals should be described by two sets of the thermodynamic parameters (i.e. segregation enthalpy and entropy): one of them correlating the segregation under the compensation temperature, the other one for the segregation at higher temperatures. (C) 2015 Elsevier B.V. All rights reserved.