Uncovering the re-distribution mechanism of Ni in a de-alloyed Ni-Cr alloy in molten fluorinated salts
Abstract A mechanism of Ni redeposition during dealloying corrosion of Ni-Cr is investigated. A model Ni20Cr (wt%) metal alloy was exposed to molten LiF-NaF-KF eutectic (FLiNaK) at 600 °C and at an applied potential of +2.1 VK+/K, above the critical potential for onset of dealloying. Upon extended e...
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Nature Portfolio
2025-07-01
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| Series: | npj Materials Degradation |
| Online Access: | https://doi.org/10.1038/s41529-025-00634-2 |
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| author | Sean H. Mills Ho Lun Chan Nathan Bieberdorf Elena Romanovskaia Valentin Romanovski Minh H. Tran Laurent Capolungo Mark Asta John R. Scully Andrew M. Minor Peter Hosemann |
| author_facet | Sean H. Mills Ho Lun Chan Nathan Bieberdorf Elena Romanovskaia Valentin Romanovski Minh H. Tran Laurent Capolungo Mark Asta John R. Scully Andrew M. Minor Peter Hosemann |
| author_sort | Sean H. Mills |
| collection | DOAJ |
| description | Abstract A mechanism of Ni redeposition during dealloying corrosion of Ni-Cr is investigated. A model Ni20Cr (wt%) metal alloy was exposed to molten LiF-NaF-KF eutectic (FLiNaK) at 600 °C and at an applied potential of +2.1 VK+/K, above the critical potential for onset of dealloying. Upon extended exposure times (up to 12 h), prominent salt-filled corrosion channels emerge along grain boundaries. A unique grain boundary corrosion mechanism, with respect to the exposed faces of the grains, a central focus of this investigation, is intrinsically connected to the formation of high purity Ni-rich de-alloyed regions within the salt-filled channel. We implement microscale techniques such as energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD) to uncover morphological and compositional variations in relevance to the formation of bicontinuous porosity from corrosion dealloying. To rationalize our findings, a phase-field model is developed and discovers a mechanism in which dissolved Ni from one grain can be redeposited on an adjacent grain at a given difference in interfacial energies. The interaction of chemical and structural factors at the grain boundaries plays a central role in elucidating the dynamics of this phenomenon and its implications towards corrosion. |
| format | Article |
| id | doaj-art-e8824a132f7445fdad1595434e7750d2 |
| institution | Kabale University |
| issn | 2397-2106 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | Nature Portfolio |
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| series | npj Materials Degradation |
| spelling | doaj-art-e8824a132f7445fdad1595434e7750d22025-08-20T03:42:56ZengNature Portfolionpj Materials Degradation2397-21062025-07-019111210.1038/s41529-025-00634-2Uncovering the re-distribution mechanism of Ni in a de-alloyed Ni-Cr alloy in molten fluorinated saltsSean H. Mills0Ho Lun Chan1Nathan Bieberdorf2Elena Romanovskaia3Valentin Romanovski4Minh H. Tran5Laurent Capolungo6Mark Asta7John R. Scully8Andrew M. Minor9Peter Hosemann10Department of Materials Science and Engineering, University of CaliforniaDepartment of Materials Science and Engineering, University of VirginiaDepartment of Materials Science and Engineering, University of CaliforniaDepartment of Materials Science and Engineering, University of VirginiaDepartment of Materials Science and Engineering, University of VirginiaDepartment of Materials Science and Engineering, University of VirginiaMaterials Science and Technology Division, Los Alamos National LaboratoryDepartment of Materials Science and Engineering, University of CaliforniaDepartment of Materials Science and Engineering, University of VirginiaDepartment of Materials Science and Engineering, University of CaliforniaMaterials Sciences Division, Lawrence Berkeley National LaboratoryAbstract A mechanism of Ni redeposition during dealloying corrosion of Ni-Cr is investigated. A model Ni20Cr (wt%) metal alloy was exposed to molten LiF-NaF-KF eutectic (FLiNaK) at 600 °C and at an applied potential of +2.1 VK+/K, above the critical potential for onset of dealloying. Upon extended exposure times (up to 12 h), prominent salt-filled corrosion channels emerge along grain boundaries. A unique grain boundary corrosion mechanism, with respect to the exposed faces of the grains, a central focus of this investigation, is intrinsically connected to the formation of high purity Ni-rich de-alloyed regions within the salt-filled channel. We implement microscale techniques such as energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD) to uncover morphological and compositional variations in relevance to the formation of bicontinuous porosity from corrosion dealloying. To rationalize our findings, a phase-field model is developed and discovers a mechanism in which dissolved Ni from one grain can be redeposited on an adjacent grain at a given difference in interfacial energies. The interaction of chemical and structural factors at the grain boundaries plays a central role in elucidating the dynamics of this phenomenon and its implications towards corrosion.https://doi.org/10.1038/s41529-025-00634-2 |
| spellingShingle | Sean H. Mills Ho Lun Chan Nathan Bieberdorf Elena Romanovskaia Valentin Romanovski Minh H. Tran Laurent Capolungo Mark Asta John R. Scully Andrew M. Minor Peter Hosemann Uncovering the re-distribution mechanism of Ni in a de-alloyed Ni-Cr alloy in molten fluorinated salts npj Materials Degradation |
| title | Uncovering the re-distribution mechanism of Ni in a de-alloyed Ni-Cr alloy in molten fluorinated salts |
| title_full | Uncovering the re-distribution mechanism of Ni in a de-alloyed Ni-Cr alloy in molten fluorinated salts |
| title_fullStr | Uncovering the re-distribution mechanism of Ni in a de-alloyed Ni-Cr alloy in molten fluorinated salts |
| title_full_unstemmed | Uncovering the re-distribution mechanism of Ni in a de-alloyed Ni-Cr alloy in molten fluorinated salts |
| title_short | Uncovering the re-distribution mechanism of Ni in a de-alloyed Ni-Cr alloy in molten fluorinated salts |
| title_sort | uncovering the re distribution mechanism of ni in a de alloyed ni cr alloy in molten fluorinated salts |
| url | https://doi.org/10.1038/s41529-025-00634-2 |
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