Kinetics and thermodynamics of Cr nanocluster formation in Fe–Cr system

The thermodynamic and kinetic models of cluster formation in binary alloys under thermal ageing have been developed in this work. Thermodynamic analysis of Fe–Cr in terms of Gibbs free energy minimization method revealed that the interphase surface energy is one of the main factors determining the cluster composition. The models were applied to describe the Cr nanocluster formation in Fe–20Cr binary alloy under thermal ageing at 773 K. The calculation of energy characteristics of Cr-rich clusters is performed in terms of molecular statics method by using many-body classic potential which describes well complex formation energy curve of Fe–Cr alloy. According to the numerical solution of Fokker–Planck equation the description of the growth kinetics of nanoclusters in Fe–20Cr has been performed. It was shown that the clusters growth may be satisfactorily explained in terms of the diffusion model.

► Cluster interface energy defines the phase composition of binary alloys.
► We developed the thermodynamic model of binary alloy containing nanoscale clusters.
► The kinetic model of nanocluster growth in thermally aged binary alloy was developed.
► Composition of binary alloy was assumed to depend on the average cluster size.
► The models are in good accordance with experimental data for Fe–20Cr at 500 °C.