A new method for the simulation of alloys: Application to interfacial segregation

Abstract

We present a new, accurate method for determining the properties of defects in alloys at finite temperature, including equilibrium segregation. This method is based upon a point approximation for the configurational entropy, an Einstein model for vibrational contributions to the free energy and may be employed with any type of description of atomic interactions. The atomic structure, segregation and thermodynamics of a defect in an alloy is determined by minimizing the free energy with respect to atomic coordinates and composition of each site at constant chemical potential. In order to test the accuracy of this approach, we compare our results with accurate Monte Carlo determinations. Overall, very good agreement for segregation to free surfaces and grain boundaries in CuNi alloys is obtained. One of the main advantages this new method enjoys over other methods such as Monte Carlo, is the efficiency with which the atomic structure of a defect, segregation and thermodynamic properties can be determined. This efficiency is obtained in the framework of a very straightforward method and with little loss in accuracy. © 1991.