Atomic-based phase-field method for the modeling of radiation induced segregation in Fe–Cr

J.B. Piochaud (1) , M. Nastar (2, 3) , F. Soisson (2, 3) , L. Thuinet (1) , A. Legris (1)

1 UMET - Unité Matériaux et Transformations - UMR 8207
2 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
3 SRMP - Service de recherches de métallurgie physique

We present a quantitative phase-field modeling of radiation-induced segregation in Fe–Cr alloys. The evolution of chemical and point defect concentration fields are described by an Onsager formalism combined to a Cahn–Hilliard like diffusion equation for the introduction of non-uniform driving forces. Both the Onsager transport coefficients and the driving force parameters are extracted from atomic Monte Carlo simulations with point defect diffusion models fitted on DFT calculations, in a composition range between 0 and 20 at.% Cr and in a temperature range between 600 and 1000 K. Phase-field simulations are able to quantitatively reproduce the evolution of segregation profiles obtained from direct atomistic kinetic Monte Carlo simulations, while being typically two orders of magnitude faster. It is shown that a precise parameterization of the concentration-dependent Onsager transport coefficients, thermodynamic factors, and equilibrium point defect concentrations is crucial for the phase-field method to be quantitative.

Mots clés: Iron–chromium alloys; Monte Carlo simulations; Phase-field model; Radiation induced segregation

Domaines: Physique Nucléaire Théorique [nucl-th]; Physique Nucléaire Expérimentale [nucl-ex]

J.B. Piochaud, M. Nastar, F. Soisson, L. Thuinet, A. Legris. Atomic-based phase-field method for the modeling of radiation induced segregation in Fe–Cr. Computational Materials Science, 2016, 122, pp.249-262. ⟨10.1016/j.commatsci.2016.05.021⟩. ⟨cea-02389670⟩