Tellurium-induced corrosion and cracking behavior of GH3535 alloy in molten FLiNaK salt

摘要

During the operation of molten salt reactors, alloys exposed to the fuel salt are vulnerable to fission product tellurium-induced corrosion and cracking[1]. This type of corrosion is found to be sensitive to Te content and the redox potential of the fuel salt, hence is not easily simulated in the laboratory experiment [2,3]. In this stduy, corrosion tests of GH3535 alloy in non-radioactive molten FLiNaK salts, with Cr3Te4 as tellurium source and different EuF3 additions to adjust the salt redox potential, were carried out at 700°C. The result show that samples exposed to Cr 3Te4 added salts all exhibited intergranular corrosion and cracking, and cracking severity were enhanced with increasing EuF3 concentration from 0 to 3wt.%, although Te contents in all these samples were below the detection limitation of EPMA. On contrary, the control samples exposed to the salt with only 3wt.% EuF 3 addition show less obvious intergranular corrosion and no cracking. The synergistic effect between EuF3 and Cr3Te4 promoted the grain boundary Te segregation and Cr depletion, hence caused severer intergranular cracking. Present experiment design may serve as a readily surrogate approach for future Te corrosion studies.