- By:
- Gordon, Ryan; Sasidhar, Kasturi; Their, Ryan; Pillai, Rishi R; Willing, Evan; Couet, Adrien; Tiley, Jaimie S; Zinkle, Steve; Sridharan, Kumar
- Journal Name:
- Materials and Corrosion
- Page Number:
- 1-14
- Volume:
- TBD
- Publication Date:
- November 13, 2025
- View DOI Listing:
- https://doi.org/10.1002/maco.70079
Abstract
The corrosion behavior of a high creep strength carbide-phase strengthened Ni-based alloy in molten FLiNaK (LiF-NaF-KF: 46.5-11.5-42 mol%) salt in the temperature range of 700°C–750°C has been investigated as a part of the development of structural alloys for fluoride salt-based molten salt reactors (MSRs). The alloy composition was designed based on Hastelloy-N, but with the goal of improving creep strength. Cr depletion depth, a measure of corrosion, was observed to be single micrometers after several hundred hours of corrosion testing. Sequential corrosion testing involving testing of pre-tested samples in fresh salt coupled with SEM-EDS, scanning transmission electron microscopy (STEM) examinations and thermodynamic and kinetic modeling, suggest that the corrosion rate at the alloy-salt interface is governed by diffusion of elements from the alloy bulk to the surface. The carbide phases in the corrosion-tested sample microstructure were identified to be largely M6C-type Mo-rich carbides and MC-type mixed carbides. Atom probe tomography (APT) showed some partitioning of Cr and Ti to the carbide phase and showed the carbide phases to be stable at the salt-facing surface.
