Corrosion Behavior of the GH3535 and C276 Alloys at the Liquid/Gas LiCl–KCl Salt Interface at 550 °C

The safety of spent nuclear fuel pyroprocessing is threatened by molten salt corrosion, especially at metal/salt interface. Two promising candidate Ni-Mo-Cr alloys, GH3535 and Hastelloy C276 were researched at the liquid/gas LiCl–KCl salt interface at 550 °C. The lower corrosion rate of Hastelloy-C276 (2.93 mg/cm²) was detected after 216  h of corrosion. Both of salt vapor and high-temperature oxidation led to Cr-depletion and hole concentration on the GH3535 alloy, accelerating intergranular corrosion. The lower element consumption rate of the Hastelloy C276 alloy was attributed to carbide precipitation at the twin grain boundary and the low mobility of elements within it. Electrochemical corrosion was facilitated by nodular salt mud formation at the salt/metal interface.