Intergranular corrosion of high temperature alloys in molten fluoride salts

摘要: Six Ni and Fe–Ni based austenitic alloys were exposed to molten LiF–NaF–KF: 46.5–11.5–42mol% salt, commonly referred as FLiNaK, at 850°C for 500 h. Corrosion was noted occur predominantly from dealloying of Cr resulting in void formation, an effect that particularly pronounced the grain boundaries. Alloy weight-loss due fluoride salt corrosion correlated with initial Cr-content up a content about 20wt%, consistent Cr-concentrations measured salts after tests. However, nominally 20 wt% 23 containing alloys, this linearly carbon formation chromium carbide phases boundaries its subsequent dissolution into along The Cr-lean intermetallic precipitates found resistant FLiNaK salt.