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Title: Cr segregation at the FeCr surface and the origin of corrosion resistance in ferritic steels

Abstract

Structural materials in Gen-IV nuclear reactors will face severe conditions of high operating temperatures, high neutron flux exposure, and corrosive environment. Radiation effects and corrosion and chemical compatibility issues are factors that will limit the materials lifetime. Low-chromium (9-12 Cr wt.%) ferritic martensitic (F/M) steels are being considered as possible candidates because they offer good swelling resistance and good mechanical properties under extreme conditions of radiation dose and irradiation temperature. The surface chemistry of FeCr alloys, responsible for the corrosion properties, is complex. It exists today a controversy between equilibrium thermodynamic calculations, which suggest Cr depletion at the surface driven by the higher surface energy of Cr, and experimental data which suggest the oxidation process occurs in two stages, first forming a Fe-rich oxide, followed by a duplex oxide layer, and ending with a Cr-rich oxide. Moreover, it has been shown experimentally that corrosion resistance of F/M steels depends significantly on Cr content, increasing with increasing Cr content and with a threshold around 10% Cr, below which, the alloy behaves as pure Fe. In an attempt to rationalize these two contradicting observations and to understand the physical mechanism behind corrosion resistance in these materials we perform atomistic simulations using ourmore » FeCr empirical potential and analyze Cr equilibrium distributions at different compositions and temperatures in single and polycrystalline samples. We analyze the controversy in terms of thermodynamic and kinetic considerations.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
945831
Report Number(s):
LLNL-CONF-409083
TRN: US200903%%820
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: Presented at: MRS Fall Meeting, Boston, MA, United States, Dec 01 - Dec 05, 2008
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; ALLOYS; BUILDING MATERIALS; CHEMISTRY; CORROSION; CORROSION RESISTANCE; FERRITIC STEELS; IRRADIATION; KINETICS; MECHANICAL PROPERTIES; NEUTRON FLUX; OXIDATION; OXIDES; RADIATION DOSES; RADIATION EFFECTS; REACTORS; SEGREGATION; STEELS; SURFACE ENERGY; THERMODYNAMICS

Citation Formats

De Caro, M S, Morse, B, Egiebor, N, Farmer, J, and Caro, A. Cr segregation at the FeCr surface and the origin of corrosion resistance in ferritic steels. United States: N. p., 2008. Web.
De Caro, M S, Morse, B, Egiebor, N, Farmer, J, & Caro, A. Cr segregation at the FeCr surface and the origin of corrosion resistance in ferritic steels. United States.
De Caro, M S, Morse, B, Egiebor, N, Farmer, J, and Caro, A. Sat . "Cr segregation at the FeCr surface and the origin of corrosion resistance in ferritic steels". United States. https://www.osti.gov/servlets/purl/945831.
@article{osti_945831,
title = {Cr segregation at the FeCr surface and the origin of corrosion resistance in ferritic steels},
author = {De Caro, M S and Morse, B and Egiebor, N and Farmer, J and Caro, A},
abstractNote = {Structural materials in Gen-IV nuclear reactors will face severe conditions of high operating temperatures, high neutron flux exposure, and corrosive environment. Radiation effects and corrosion and chemical compatibility issues are factors that will limit the materials lifetime. Low-chromium (9-12 Cr wt.%) ferritic martensitic (F/M) steels are being considered as possible candidates because they offer good swelling resistance and good mechanical properties under extreme conditions of radiation dose and irradiation temperature. The surface chemistry of FeCr alloys, responsible for the corrosion properties, is complex. It exists today a controversy between equilibrium thermodynamic calculations, which suggest Cr depletion at the surface driven by the higher surface energy of Cr, and experimental data which suggest the oxidation process occurs in two stages, first forming a Fe-rich oxide, followed by a duplex oxide layer, and ending with a Cr-rich oxide. Moreover, it has been shown experimentally that corrosion resistance of F/M steels depends significantly on Cr content, increasing with increasing Cr content and with a threshold around 10% Cr, below which, the alloy behaves as pure Fe. In an attempt to rationalize these two contradicting observations and to understand the physical mechanism behind corrosion resistance in these materials we perform atomistic simulations using our FeCr empirical potential and analyze Cr equilibrium distributions at different compositions and temperatures in single and polycrystalline samples. We analyze the controversy in terms of thermodynamic and kinetic considerations.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2008},
month = {11}
}

Conference:
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