VANADIUM ALLOYS AS STRUCTURAL-MATERIALS FOR LIQUID LITHIUM BLANKET OF FUSION-REACTORS

The behaviour of V and V-5Ti, V-15Ti-10Cr-0.05Y, V-8Cr-1Zr-0.1C, V-8Cr-5Ti-1Zr-0.1C, V-4Cr-0.5Ti-0.1Zr-0.04Si, V-9Ti-5Cr-0.04Zr-0.04Si alloys was studied. Experiments were conducted under static conditions at 450 and 700-degrees-C for exposure times up to 2600 h. Experiments in dynamic lithium with 400 wppm nitrogen contamination were also conducted in the convection loop at 450-degrees-C for 2600 h Li exposure. Neither significant corrosion nor deterioration of mechanical properties were found after the static lithium tests at 450-degrees-C. Experiments at 700-degrees-C for 1050 h showed that without protective covering V-base alloys cannot be used as blanket structural materials at this temperature. Mass transfer of the V-base materials studied in flowing lithium does not depend on alloy composition; the average dissolution rate is 1.3 mg/(m2 h). It appears that the protective nitride film formed on the sample surfaces, decreases the dissolution rate of the V-base alloys, retards further nitrogen and carbon mass transfer, and thus minimizes the effect of a lithium environment on mechanical properties.