Positron annihilation analysis of the atomic scale changes in oxidized Zircaloy-4 samples

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Positron annihilation analysis of the atomic scale changes in oxidized Zircaloy-4 samples. / Heikinheimo, J.; Ortner, S.; Makkonen, I.; Kujala, J.; Blackmur, M.; Tuomisto, F.

In: Journal of Nuclear Materials, Vol. 495, 01.11.2017, p. 172-180.

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@article{01a96f47e3d9414893c1b985362f8c06,
title = "Positron annihilation analysis of the atomic scale changes in oxidized Zircaloy-4 samples",
abstract = "The process of oxidation in zirconium alloys is not straightforward. It includes cyclic periods, where the oxidation rate is decelerating as a function of increasing oxide thickness. Transition to the higher oxidation rate happens approximately after every 2 μm oxide growth and each cycle is associated with a layer of oxide with little or no cracking and a similar thickness layer with a large number of micro-scale lateral cracks. This work uses positron annihilation Doppler broadening spectroscopy to investigate the development of atomic-scale defect features in the oxides on Zircaloy-4 samples exposed to alkaline water at 350 °C. Results from the Doppler broadening measurements supported by Density Functional Theory calculations indicate that complexes involving both zirconium-site and oxygen-site vacancies exist in the oxide. The implications of the vacancies in the oxide layer are considered for oxygen diffusion and the oxidation rate.",
keywords = "Doppler broadening, Positron annihilation spectroscopy, Zirconium oxidation",
author = "J. Heikinheimo and S. Ortner and I. Makkonen and J. Kujala and M. Blackmur and F. Tuomisto",
year = "2017",
month = "11",
day = "1",
doi = "10.1016/j.jnucmat.2017.08.004",
language = "English",
volume = "495",
pages = "172--180",
journal = "Journal of Nuclear Materials",
issn = "0022-3115",

}

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TY - JOUR

T1 - Positron annihilation analysis of the atomic scale changes in oxidized Zircaloy-4 samples

AU - Heikinheimo, J.

AU - Ortner, S.

AU - Makkonen, I.

AU - Kujala, J.

AU - Blackmur, M.

AU - Tuomisto, F.

PY - 2017/11/1

Y1 - 2017/11/1

N2 - The process of oxidation in zirconium alloys is not straightforward. It includes cyclic periods, where the oxidation rate is decelerating as a function of increasing oxide thickness. Transition to the higher oxidation rate happens approximately after every 2 μm oxide growth and each cycle is associated with a layer of oxide with little or no cracking and a similar thickness layer with a large number of micro-scale lateral cracks. This work uses positron annihilation Doppler broadening spectroscopy to investigate the development of atomic-scale defect features in the oxides on Zircaloy-4 samples exposed to alkaline water at 350 °C. Results from the Doppler broadening measurements supported by Density Functional Theory calculations indicate that complexes involving both zirconium-site and oxygen-site vacancies exist in the oxide. The implications of the vacancies in the oxide layer are considered for oxygen diffusion and the oxidation rate.

AB - The process of oxidation in zirconium alloys is not straightforward. It includes cyclic periods, where the oxidation rate is decelerating as a function of increasing oxide thickness. Transition to the higher oxidation rate happens approximately after every 2 μm oxide growth and each cycle is associated with a layer of oxide with little or no cracking and a similar thickness layer with a large number of micro-scale lateral cracks. This work uses positron annihilation Doppler broadening spectroscopy to investigate the development of atomic-scale defect features in the oxides on Zircaloy-4 samples exposed to alkaline water at 350 °C. Results from the Doppler broadening measurements supported by Density Functional Theory calculations indicate that complexes involving both zirconium-site and oxygen-site vacancies exist in the oxide. The implications of the vacancies in the oxide layer are considered for oxygen diffusion and the oxidation rate.

KW - Doppler broadening

KW - Positron annihilation spectroscopy

KW - Zirconium oxidation

UR - http://www.scopus.com/inward/record.url?scp=85027726108&partnerID=8YFLogxK

U2 - 10.1016/j.jnucmat.2017.08.004

DO - 10.1016/j.jnucmat.2017.08.004

M3 - Article

VL - 495

SP - 172

EP - 180

JO - Journal of Nuclear Materials

JF - Journal of Nuclear Materials

SN - 0022-3115

ER -

ID: 14874438