Role of defect trapping in the enhanced corrosion resistance of Ni-Mo alloys with yttrium and yttrium oxide additions
Abstract
Corrosion of structural alloys remains a critical challenge for advanced molten salt reactors, where aggressive fluoride salts promote continuous dissolution at the salt-metal interface. While most mitigation strategies emphasize thermodynamic stability, kinetic control of atomic transport has received comparatively less attention. Here, we propose a corrosion mitigation strategy based on diffusion control and vacancy trapping by dilute yttrium (Y) solutes and yttrium oxide (Y2O3) dispersions in Ni alloys. A combined computational and experimental approach integrates density functional theory (DFT), self-consistent mean-field (SCMF) diffusion modeling, and an impurity trapping model to quantify the impact of defect trapping on effective vacancy mobility. Strong first-nearest-neighbor vacancy-Y binding, off-lattice vacancy configurations, and elevated rotational and dissociation barriers result in pronounced suppression of vacancy diffusivity, while Y2O3-associated sites treated as fixed traps in the model further reduce the mobile vacancy population. Ni-Mo (NM), Y-modified (NMY), and Y2O3-containing (NMYO) alloys were tested in molten fluoride salt at 750°C. Corrosion penetration decreases systematically from NM to NMY to NMYO, consistent with the predicted reduction in vacancy-mediated transport. The same trend is observed in mass change, with net weight loss decreasing from 0.52% for NM to 0.23% for NMY and 0.09% for NMYO. These results are consistent with an alloy-side transport contribution from defect trapping and reduced atomic transport. This study therefore suggests point defect engineering as a promising alloy design strategy for extreme nuclear environments.
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BibTeX
@misc{ke2026role,
title = {{Role of defect trapping in the enhanced corrosion resistance of Ni-Mo alloys with yttrium and yttrium oxide additions}},
author = {Jia-Hong Ke and Xinchang Zhang and Jingfan Yang and Qiufeng Yang and Ruchi Gakhar and Rongjie Song},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.15089},
eprint = {2610.15089},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.15089},
}
RIS
TY - UNPB
TI - Role of defect trapping in the enhanced corrosion resistance of Ni-Mo alloys with yttrium and yttrium oxide additions
AU - Jia-Hong Ke
AU - Xinchang Zhang
AU - Jingfan Yang
AU - Qiufeng Yang
AU - Ruchi Gakhar
AU - Rongjie Song
PY - 2026
DA - 2026/10/10
PB - arXiv
DO - 10.48550/arxiv.2610.15089
UR - https://arxiv.org/abs/2610.15089
AB - Corrosion of structural alloys remains a critical challenge for advanced molten salt reactors, where aggressive fluoride salts promote continuous dissolution at the salt-metal interface. While most mitigation strategies emphasize thermodynamic stability, kinetic control of atomic transport has received comparatively less attention. Here, we propose a corrosion mitigation strategy based on diffusion control and vacancy trapping by dilute yttrium (Y) solutes and yttrium oxide (Y_2O_3) dispersions in Ni alloys. A combined computational and experimental approach integrates density functional theory (DFT), self-consistent mean-field (SCMF) diffusion modeling, and an impurity trapping model to quantify the impact of defect trapping on effective vacancy mobility. Strong first-nearest-neighbor vacancy-Y binding, off-lattice vacancy configurations, and elevated rotational and dissociation barriers result in pronounced suppression of vacancy diffusivity, while Y_2O_3-associated sites treated as fixed traps in the model further reduce the mobile vacancy population. Ni-Mo (NM), Y-modified (NMY), and Y_2O_3-containing (NMYO) alloys were tested in molten fluoride salt at 750°C. Corrosion penetration decreases systematically from NM to NMY to NMYO, consistent with the predicted reduction in vacancy-mediated transport. The same trend is observed in mass change, with net weight loss decreasing from 0.52% for NM to 0.23% for NMY and 0.09% for NMYO. These results are consistent with an alloy-side transport contribution from defect trapping and reduced atomic transport. This study therefore suggests point defect engineering as a promising alloy design strategy for extreme nuclear environments.
ER -