Air contamination effects on the compatibility of liquid lithium with molybdenum; TZM,niobium, stainless steels,nickel and hastelloy N in stainless-steel vessels at 600°c

The effects of nonmetallic impurities on the compatibility of liquid lithium with molybdenum, TZM, niobium, type 304 and type 316 stainless steels, nickel and Hastelloy N were investigated. Three compatibility tests (test I, test II and test III), classified by the grade of air contamination of the lithium, were conducted at 600°C for about 1000 h in stainless-steel vessels. In each test the above-mentioned specimens were immersed together in the lithium. In test I weight gain was observed for all the specimens except nickel and Hastelloy N. However, in test II and test III, weight loss was observed for all the specimens. MoNi₃ was produced on the surface of the molybdenum and TZM specimens as a result of the reaction between molybdenum and nickel dissolved in the liquid lithium. NbN_0.9O_0.1 was observed on the surface of niobium specimens in test I and test II, and Nb₂N in test II and test III. The surface of the stainless-steel specimens in test II and test III was depleted with nickel and chromium elements, and deteriorated. The corrosion rates of the test specimens in test III were about 2, 5, 26 and 22 μm/yr for molybdenum or TZM, niobium, type 304 stainless steel and type 316, respectively. Nickel and Hastelloy N were severely attacked by liquid lithium at 600°C. These results were obtained for liquid lithium with a high nickel concentration.