Hydrogen concentration distribution in vanadium-base alloys after surface preparation and exposure to liquid lithium

The objective of this research is to provide guidance on the applicability of vanadium-base alloys for structural components in a fusion reactor. The H concentration distributions in near-surface layers of V-15Cr-5-Ti and V-3Ti-0.5Si alloy specimens were determined by use of a chemical dissolution technique together with a determination of the hydrogen partial pressure on heating the specimens. These results contribute to an understanding for the exceptional resistance to hydrogen embrittlement of the V-3Ti-0.5Si alloy in comparison to the V-15Cr-5Ti alloy. Also, the H concentration distributions in the V-15Cr-5Ti and V-3Ti-0.5Si alloys were determined after immersion in liquid lithium at 5000C for 20-25 h. The H concentration in the V-15Cr-5Ti alloy decreased from an initial level of 0.19 at. % to 0.002 at. % and the H concentration in the V-3Ti-0.5Si alloy decreased from 0.31 at. % to 0.34 at. % after the lithium exposure. These results suggest that the greater loss of ductility exhibited by the V-15Cr-5Ti alloy, in comparison to the V-3Ti-1Si and V-20Ti alloys, on neutron irradiation is not attributable to an increased H concentration. Significant amounts of H were evolved from corrosion products formed on the surface of the V-31-0.5Si alloy during the lithium exposure. The V-3Ti-0.5Si alloy has a twofold greater propensity for H uptake than the V-15Cr-5Ti alloy. 10 references, 9 figures, 3 tables