EVALUATION OF THE OXYGEN DIFFUSION COEFFICIENT IN NICKEL-BASE ALLOYS

Title
EVALUATION OF THE OXYGEN DIFFUSION COEFFICIENT IN NICKEL-BASE ALLOYS
Authors
남효온윤재영김지현황일순이규환
Keywords
PWSCC; oxygen diffusivity; nickel base alloy
Issue Date
2011-08
Publisher
15th International Conference on Environmental Degradation of Materials in Nuclear Power Systems: Water Reactors
Abstract
Nickel-base alloys such as alloy 600 (Ni-16Cr-9Fe) are known to exhibit intergranular stress corrosion cracking (IGSCC) at pressurized water reactor (PWR) primary water environments. From the microscopic observations, it was found that oxygen plays a role in primary water stress corrosion cracking (PWSCC) of nickel-base alloys and Scott suggests an internal oxidation model. However, it was found that needed oxygen diffusivity to explain the internal oxidation model should be several orders greater than the measured oxygen diffusivity. In this study, oxygen diffusion coefficients in the nickel-base alloys were evaluated by atomistic modeling of oxygen diffusion process based on the proposed vacancy-mediated diffusion model. Density functional theory is used to calculate the energy of a system. Activation barrier energy of diffusion of atomic oxygen is quantified by finding minimum energy path through the most favorable path. Phonon analysis is performed using the direct force-constant method.
URI
http://pubs.kist.re.kr/handle/201004/40893
ISSN
978-1-118
Appears in Collections:
KIST Publication > Conference Paper
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