Ab Initio Based Modelling of Diffusion and Phase Stability of Alloys

Abstract

abstractEN: In this chapter, we present the basic principles and methods for modelling of diffusion and phase stability of alloys using ab-initio methods. We review briefly first-principles methods and their most important approximations. The direct and approximated methods of prediction of migration energies are shown both for pure metals and for alloys. The cluster expansion method is described in more detail. We show that it can be applied to understand interactions in the alloys, to generate the representative structures of alloys and to predict migration barriers in alloys. We describe the methods to compute the effective cluster interactions and to assess the accuracy of the model. Finally, we present the examples of Monte Carlo simulations with parameters obtained from cluster expansion method. We show that the ordering in alloys can be predicted by the calculations of Warren-Cowley parameters. We investigate also the role of entropy in the stability of alloys at elevated temperatures.score: 0collation: 1-2