Interatomic potential to study the formation of NiCr clusters in high Cr ferritic steels

• Under irradiation NiSiPCr clusters are formed in high-Cr ferritic martensitic steels as well as in FeCr model alloys. In the literature little is known about the origin and contribution to the hardening of these clusters. In this work we performed density functional theory (DFT) calculations to study the stability of small substitutional NiCr-vacancy clusters and interstitial configurations in bcc Fe. Based on DFT data and experimental considerations a ternary potential for the ferritic FeNiCr system was developed. The potential was applied to study the thermodynamic stability of NiCr clusters by means of Metropolis Monte Carlo (MMC) simulations. The results of our simulations show that Cr and Ni precipitate as separate fractions and suggest only a limited synergetic effect between Ni and Cr. Therefore our results suggest that the NiCrSiP clusters observed in experiments must be the result of other mechanisms than the synergy of Cr and Ni at thermal equilibrium.

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Nyckelord

Alloy steel

Density functional theory

Ferrite

Martensitic steel

Monte Carlo methods

Nickel

Radiation damage

Thermodynamic stability

Ferritic-martensitic steels

High Cr ferritic steel

Interatomic potential

Metropolis Monte Carlo

Model alloys

Synergetic effect

Thermal equilibriums

Vacancy cluster

Ferritic steel

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