Title: Rapid Diffusion and Nanosegregation of Hydrogen in Magnesium Alloys from Exposure to Water

Abstract

Hydrogen gas is formed when Mg corrodes in water; however, the manner and extent to which the hydrogen may also enter the Mg metal is poorly understood. Such knowledge is critical as stress corrosion cracking (SCC)/embrittlement phenomena limit many otherwise promising structural and functional uses of Mg. Here, we report via D₂O/D isotopic tracer and H₂O exposures with characterization by secondary ion mass spectrometry, inelastic neutron scattering vibrational spectrometry, electron microscopy, and atom probe tomography techniques direct evidence that hydrogen rapidly penetrated tens of micrometers into Mg metal after only 4 h of exposure to water at room temperature. Further, technologically important microalloying additions of <1 wt % Zr and Nd used to improve the manufacturability and mechanical properties of Mg significantly increased the extent of hydrogen ingress, whereas Al additions in the 2–3 wt % range did not. Segregation of hydrogen species was observed at regions of high Mg/Zr/Nd nanoprecipitate density and at Mg(Zr) metastable solid solution microstructural features. We also report evidence that this ingressed hydrogen was unexpectedly present in the alloy as nanoconfined, molecular H₂. These new insights provide a basis for strategies to design Mg alloys to resist SCC in aqueous environments as well as potentiallymore » impact functional uses such as hydrogen storage where increased hydrogen uptake is desired.« less

Authors:

Brady, Michael P.  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-1338-4747"
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Ievlev, Anton V.  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-3645-0508"
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Fayek, Mostafa ^[2]; Leonard, Donovan N. ^[1]; Frith, Matthew G. ^[1]; Meyer, III, Harry M. ^[1]; Ramirez-Cuesta, Anibal J. ^[1]; Daemen, Luke L. ^[1]; Cheng, Yongqiang ^[1]; Guo, Wei ^[1]; Poplawsky, Jonathan D. ^[1]; Ovchinnikova, Olga S. ^[1]; Thomson, Jeffrey ^[1]; Anovitz, Lawrence M. ^[1]; Rother, Gernot  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-4921-6294"
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Shin, Dongwon ^[1]; Song, Guang-Ling ^[1]; Davis, Bruce ^[3]

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+ Show Author Affiliations

1. Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee 37831, United States
2. Department of Geological Sciences, University of Manitoba (UM), Winnipeg, MB R3T 2N2, Canada
3. Magnesium Elektron North America (MENA), Madison, Illinois 62060, United States

Publication Date:

2017-10-18

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE), Transportation Office. Vehicle Technologies Office; USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)

OSTI Identifier:

1400005

Alternate Identifier(s):

OSTI ID: 1408592

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Published Article

Journal Name:

ACS Applied Materials and Interfaces

Additional Journal Information:

Journal Name: ACS Applied Materials and Interfaces Journal Volume: 9 Journal Issue: 43; Journal ID: ISSN 1944-8244

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

08 HYDROGEN; 36 MATERIALS SCIENCE; corrosion; hydrogen; hydrogen storage; magnesium; stress corrosion cracking (SCC)