Stress-assisted corrosion behaviour of Hastelloy N in FLiNaK molten salt environment

Abstract

The use of molten-salt–based energy production and storage systems requires high-temperature corrosion- and creep-resistant structural materials. This study investigated the microstructure evolution and corrosion characteristics of Hastelloy N under working stress in a molten salt environment. Selective diffusion of Cr at the grain boundaries (GBs) of the Hastelloy N degraded the properties of the GBs, making them preferred locations for corrosion crack invasion. Stress further promoted Cr diffusion and accelerated GB carbide precipitation, thereby forming a corrosion couple between the carbide and matrix that facilitated the expansion of intergranular corrosion cracks into the grains. These findings are useful for providing advances in the design of novel structural alloys with extraordinary property-microstructure stability combinations for resistant to complex molten salt environments.

Corrosion Electrochemistry of Chromium in Molten FLiNaK Salt at 600 °C

“…Based on the literature that utilized the ICP-MS or ICP-OES technique to identify metallic cation impurities in FLiNaK, it was expected that a commercial salt mixture may contain between 10 and 60 ppm of Cr ions along with Fe, Ni, Rh etc. 31,[38][39][40][41] This validates the assumption of these ionic activities.…”

Microstructure and mechanical properties of Ti2Ni alloy fabricated by direct energy deposition

“…17 Ti 2 Ni phase is a hard and brittle phase, which leads to the material embrittlement. 18 Ti 2 Ni phase fractures the specimen at the initial stage of plastic deformation, which results in the crack formation and propagation.…”