Unraveling Impurity-Dependent Morphological and Chemical Evolution of Ni-20Cr Alloy in Eutectic LiCl-KCl Molten Salt

Yuxiang Peng; Kaustubh K. Bawane; Xiaoyang Liu; Xiaoyin Zheng; Mingyuan Ge; Xianghui Xiao; Ellie M. Kim; Phillip W. Halstenberg; Sheng Dai; James F. Wishart; Yu Chen Karen Chen-Wiegart

doi:10.1021/acsami.4c23034

Unraveling Impurity-Dependent Morphological and Chemical Evolution of Ni-20Cr Alloy in Eutectic LiCl-KCl Molten Salt

Yuxiang Peng, Kaustubh K. Bawane, Xiaoyang Liu, Xiaoyin Zheng, Mingyuan Ge, Xianghui Xiao, Ellie M. Kim, Phillip W. Halstenberg, Sheng Dai, James F. Wishart, Yu Chen Karen Chen-Wiegart

Research output: Contribution to journal › Article › peer-review

Abstract

Understanding the interfacial evolution of alloys in molten salt with different amounts of water (H₂O) and oxygen (O₂) impurities is significant for applications in many fields, including concentrated solar power, molten salt reactors, and applications in pyrochemical reprocessing and electrorefining. Additionally, the impurity-driven corrosion mechanisms that lead to various morphological and chemical evolution characteristics at the interfaces of structural alloys and molten salts are not fully understood. In the present work, the three-dimensional (3D) morphological evolution of Ni-20Cr microwires in LiCl-KCl was studied at 500 °C under different moisture and oxygen conditions using in situ synchrotron transmission X-ray microscopy (TXM) and scanning transmission electron microscopy (STEM) techniques. No significant morphological changes were observed in Ni-20Cr microwires under vacuum conditions. However, the wires exhibited distinct morphological evolutions when exposed to molten salt containing H₂O alone, as well as when both H₂O and O₂ were present. Furthermore, Cr₂O₃ precipitates were observed in the molten salt during corrosion with only H₂O present, while Cr⁶⁺ species were identified in the salt when O₂ was added. These findings are crucial for understanding the corrosion mechanisms of molten salt with different amounts of H₂O and O₂ contamination, providing insights for developing corrosion mitigation methods and improving the stability of containment alloys in molten salt applications.

Original language	English
Pages (from-to)	28764-28776
Number of pages	13
Journal	ACS Applied Materials and Interfaces
Volume	17
Issue number	19
DOIs	https://doi.org/10.1021/acsami.4c23034
State	Published - May 14 2025

Funding

This work was supported as part of the Molten Salts in Extreme Environments (MSEE) Energy Frontier Research Center, funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences. BNL, ORNL, and INL are operated under DOE contracts DE-SC0012704, DE-AC05-00OR22725, and DE-AC07-051D14517, respectively. Work at the University of Tennessee, Knoxville, and Stony Brook University was supported by MSEE through a subcontract from BNL. This research used resources and the 18-ID (Full Field X-ray Imaging, FXI) beamline of the National Synchrotron Light Source II, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract DE-SC0012704. The FIB and STEM facilities are as part of the Nuclear Science User Facilities. The authors also thank MSEE EFRC members, Dr. Adrien Couet and Dr. Katsuyo Thornton for their invaluable suggestions and comments during center meeting discussions. This work was supported as part of the Molten Salts in Extreme Environments (MSEE) Energy Frontier Research Center, funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences. BNL, ORNL, and INL are operated under DOE contracts DE-SC0012704, DE-AC05\u201300OR22725, and DE-AC07\u2013051D14517, respectively. Work at Stony Brook University and the University of Tennessee Knoxville was supported by MSEE through a subcontract from BNL. This work was supported as part of the Molten Salts in Extreme Environments (MSEE) Energy Frontier Research Center, funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences. BNL, ORNL, and INL are operated under DOE contracts DE-SC0012704, DE-AC05-00OR22725, and DE-AC07-051D14517, respectively. Work at the University of Tennessee, Knoxville, and Stony Brook University was supported by MSEE through a subcontract from BNL. This research used resources and the 18-ID (Full Field X-ray Imaging, FXI) beamline of the National Synchrotron Light Source II, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract DE-SC0012704. The FIB and STEM facilities are as part of the Nuclear Science User Facilities. The authors also thank MSEE EFRC members, Dr. Adrien Couet and Dr. Katsuyo Thornton for their invaluable suggestions and comments during center meeting discussions. This work was supported as part of the Molten Salts in Extreme Environments (MSEE) Energy Frontier Research Center, funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences. BNL, ORNL, and INL are operated under DOE contracts DE-SC0012704, DE-AC05-00OR22725, and DE-AC07-051D14517, respectively. Work at Stony Brook University and the University of Tennessee Knoxville was supported by MSEE through a subcontract from BNL.

Keywords

LiCl-KCl
Ni−20Cr
STEM
TXM
corrosion
impurities

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title = "Unraveling Impurity-Dependent Morphological and Chemical Evolution of Ni-20Cr Alloy in Eutectic LiCl-KCl Molten Salt",

abstract = "Understanding the interfacial evolution of alloys in molten salt with different amounts of water (H2O) and oxygen (O2) impurities is significant for applications in many fields, including concentrated solar power, molten salt reactors, and applications in pyrochemical reprocessing and electrorefining. Additionally, the impurity-driven corrosion mechanisms that lead to various morphological and chemical evolution characteristics at the interfaces of structural alloys and molten salts are not fully understood. In the present work, the three-dimensional (3D) morphological evolution of Ni-20Cr microwires in LiCl-KCl was studied at 500 °C under different moisture and oxygen conditions using in situ synchrotron transmission X-ray microscopy (TXM) and scanning transmission electron microscopy (STEM) techniques. No significant morphological changes were observed in Ni-20Cr microwires under vacuum conditions. However, the wires exhibited distinct morphological evolutions when exposed to molten salt containing H2O alone, as well as when both H2O and O2 were present. Furthermore, Cr2O3 precipitates were observed in the molten salt during corrosion with only H2O present, while Cr6+ species were identified in the salt when O2 was added. These findings are crucial for understanding the corrosion mechanisms of molten salt with different amounts of H2O and O2 contamination, providing insights for developing corrosion mitigation methods and improving the stability of containment alloys in molten salt applications.",

keywords = "LiCl-KCl, Ni−20Cr, STEM, TXM, corrosion, impurities",

author = "Yuxiang Peng and Bawane, {Kaustubh K.} and Xiaoyang Liu and Xiaoyin Zheng and Mingyuan Ge and Xianghui Xiao and Kim, {Ellie M.} and Halstenberg, {Phillip W.} and Sheng Dai and Wishart, {James F.} and Chen-Wiegart, {Yu Chen Karen}",

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AU - Bawane, Kaustubh K.

AU - Liu, Xiaoyang

AU - Zheng, Xiaoyin

AU - Ge, Mingyuan

AU - Xiao, Xianghui

AU - Kim, Ellie M.

AU - Halstenberg, Phillip W.

AU - Dai, Sheng

AU - Wishart, James F.

AU - Chen-Wiegart, Yu Chen Karen

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N2 - Understanding the interfacial evolution of alloys in molten salt with different amounts of water (H2O) and oxygen (O2) impurities is significant for applications in many fields, including concentrated solar power, molten salt reactors, and applications in pyrochemical reprocessing and electrorefining. Additionally, the impurity-driven corrosion mechanisms that lead to various morphological and chemical evolution characteristics at the interfaces of structural alloys and molten salts are not fully understood. In the present work, the three-dimensional (3D) morphological evolution of Ni-20Cr microwires in LiCl-KCl was studied at 500 °C under different moisture and oxygen conditions using in situ synchrotron transmission X-ray microscopy (TXM) and scanning transmission electron microscopy (STEM) techniques. No significant morphological changes were observed in Ni-20Cr microwires under vacuum conditions. However, the wires exhibited distinct morphological evolutions when exposed to molten salt containing H2O alone, as well as when both H2O and O2 were present. Furthermore, Cr2O3 precipitates were observed in the molten salt during corrosion with only H2O present, while Cr6+ species were identified in the salt when O2 was added. These findings are crucial for understanding the corrosion mechanisms of molten salt with different amounts of H2O and O2 contamination, providing insights for developing corrosion mitigation methods and improving the stability of containment alloys in molten salt applications.

AB - Understanding the interfacial evolution of alloys in molten salt with different amounts of water (H2O) and oxygen (O2) impurities is significant for applications in many fields, including concentrated solar power, molten salt reactors, and applications in pyrochemical reprocessing and electrorefining. Additionally, the impurity-driven corrosion mechanisms that lead to various morphological and chemical evolution characteristics at the interfaces of structural alloys and molten salts are not fully understood. In the present work, the three-dimensional (3D) morphological evolution of Ni-20Cr microwires in LiCl-KCl was studied at 500 °C under different moisture and oxygen conditions using in situ synchrotron transmission X-ray microscopy (TXM) and scanning transmission electron microscopy (STEM) techniques. No significant morphological changes were observed in Ni-20Cr microwires under vacuum conditions. However, the wires exhibited distinct morphological evolutions when exposed to molten salt containing H2O alone, as well as when both H2O and O2 were present. Furthermore, Cr2O3 precipitates were observed in the molten salt during corrosion with only H2O present, while Cr6+ species were identified in the salt when O2 was added. These findings are crucial for understanding the corrosion mechanisms of molten salt with different amounts of H2O and O2 contamination, providing insights for developing corrosion mitigation methods and improving the stability of containment alloys in molten salt applications.

KW - LiCl-KCl

KW - Ni−20Cr

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KW - TXM

KW - corrosion

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ER -

Unraveling Impurity-Dependent Morphological and Chemical Evolution of Ni-20Cr Alloy in Eutectic LiCl-KCl Molten Salt

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