Modeling grain boundary segregation by prediction of all the necessary parameters

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A thermodynamic model of equilibrium grain boundary segregation in real binary systems is proposed which is based on the prediction of all the necessary parameters. These parameters are (i) the standard enthalpy and (ii) the standard entropy of grain boundary segregation, both related to ideal behavior, as well as (iii) the Fowler binary interaction coefficient describing the real contribution. Application of the model is shown in detail for the example of iron-based binary systems.

Scheme of the prediction of required parameters for prediction of grain boundary segregation.
Description

Scheme of the procedure of obtaining the parameters of grain boundary segregation: in the phase diagram (a) we can read the temperature and bulk solid solubility. Using the grain boundary segregation diagram we will read the value of the standard enthalpy of solte segregation at particular grain boundary (b). Based on the enthalpy-entropy compensation effect for grain boundary segregation we obtain the value of corresponding standard segregation entropy (c). Real behavior of the system is then adjusted by the interaction coefficient on basis of the dependence derived by us (d).

Contact person: Pavel Lejček
Cooperating institutions: Max-Planck-Institute for Intelligent Systems, Stuttgart, Germany