Prediction of enthalpy and entropy of solute segregation at individual grain boundaries of α-iron and ferrite steels

For many materials intended for technical applications, it is important to know the relation between bulk and grain boundary composition. Theoretical and experimental studies of the properties of crystallographically well-defined grain boundaries disclosed various relations between characteristic parameters such as (i) the interdependence between the enthalpy of solute segregation, the bulk solid solubility and the grain boundary structure, and (ii) the linear relationship between the segregation entropy and enthalpy for all grain boundaries. It is shown that these two relationships can be used for prediction of the enthalpy and entropy of segregation of any element at any grain boundary. Capabilities and limitations of this prediction are demonstrated by comparing the predicted interfacial composition in numerous α-iron base binary systems with the experimental data measured recently as well as by application to technically important systems (low-alloy steel).