(351g) Investigating Chromium Dealloying in Molten Chloride Salt

It is well understood that selective dissolution of chromium is the primary mechanism by which structural alloys degrade in molten salt. The rate of dissolution depends on Cr solubility in the salt, and on the presence of impurities. A more complete knowledge of chromium dealloying is desired for the design of new materials, and for regulating salt conditions in molten salt reactors and concentrating solar power systems.

For this work, capsule-based corrosion experiments were conducted in which commercial alloys, Alloy-N variants, and a series of Ni-base alloys with Cr contents ranging from 7% to 24% were exposed to molten KCl-MgCl₂ or NaCl-MgCl₂ at 700°C for up to 2000 hours. Samples were weighed to determine mass change, mounted metallographically, and characterized with optical microscopy and SEM to characterize the exposed surfaces. SEM-EDS was used to measure the extent of Cr depletion near sample surfaces. The salts in which the samples were exposed were characterized with ICP-OES to understand the effect of salt Cr content on the corrosion rate of the binary alloys.

This talk will report on new insights gained into selective dissolution of Cr in molten chloride salts

This work was sponsored by the Laboratory Directed Research and Development Program of ORNL, managed by UT-Battelle, LLC, for the U.S. Department of Energy.