Hydrogen permeation and transmission electron microscope observations were performed for V–Al alloys (10 to 40mol%Al). Hydrogen permeability of V–Al alloys decreased with Al content, but not in a monotonic manner. Below 20mol%Al, the H permeability of V–Al alloys decreased linearly with Al content. From 20 to 30mol%Al, the H permeability decreased abruptly. A15 phase which was shown in the V–Al phase diagram was not observed in any samples, quenched from 1373K or aged at 853K for 100 to 350h. Instead, some precipitates of 200nm to 1μm were observed at grain boundaries, sub-boundaries and within grains. The amount of the precipitates, however, was too small to explain the significant drop of H permeability observed in the alloys with more than 20mol%Al. The long-time permeation test showed that V–10Al sample possessed satisfactory durability to be used as H purification materials.

Hydrogen Permeation and Transmission Electron Microscope Observations of V–Al Alloys. C.Nishimura, T.Ozaki, M.Komaki, Y.Zhang: Journal of Alloys and Compounds, 2003, 356-357, 295-9