Relaxation Process Due to Long-Range Diffusion of Hydrogen and Deuterium in Niobium

Alloy Design of Nb-Based Hydrogen Permeable Membrane with Strong Resistance to Hydrogen Embrittlement

“…For example, the hydrogen diffusion coefficient for pure niobium during the hydrogen permeation at 773 K is 3:07 Â 10 À9 m 2 /s, which is significantly lower than the previous works measured by the relaxation method. [14][15][16] These results are in consistent with the past findings that the hydrogen diffusion coefficient for pure niobium decreases with increasing the hydrogen concentration. 17) Surprisingly, the hydrogen diffusion during the hydrogen permeation is found to be faster in Pd-26 mol%Ag alloy with fcc crystal structure than that in bcc niobium at 773 K. It is also interesting that the addition of Ru or W into niobium increases the hydrogen diffusion coefficient during the hydrogen permeation.…”

“…9. For comparison, the reported hydrogen diffusion coefficients at 773 K for pure niobium [14][15][16] and Pd-25 mass%Ag alloy 7) are presented in On the other hand, the hydrogen diffusion coefficient for pure niobium obtained in this study is quite different from the reported values for dilute hydrogen solid solutions. For example, the hydrogen diffusion coefficient for pure niobium during the hydrogen permeation at 773 K is 3:07 Â 10 À9 m 2 /s, which is significantly lower than the previous works measured by the relaxation method.…”

Hydrogen diffusion in Ti–Nb45 at high hydrogen contents

“…Due to the interaction between the size of interstitial sites with their chemical potential, an applied bending strain on a solid leads to a diffusion of interstitial elements from lattice regions under compression to regions under tension. This effect was already postulated in 1935 [11], but the first practical prove was given more than 30 years later for a hydrogen/niobium system [12]. Since then Gorsky effect measurements were used several times for the determination of hydrogen diffusion coefficients in metals and alloys (e.g.…”

United States Air Force Summer Faculty Research Program. Program Technical Report. 1990. Volume 3

“…This deviation at low temperatures has also been observed experimentally for hydrogen permeation in tantalum (Kokkinidis, 1977) for temperatures less than 200 K and as low as 100 K and in niobium (Schaumann et al, 1968) for temperatures less than 250 K and as low as 120 K.…”

“…In fact, its mobility is several orders of magnitude larger than other interstitials such as oxygen and nitrogen. In addition to moderate to high temperatures, hydrogen diffusion can also be observed at low temperatures due to quantum effects at the molecular level (Schaumann et al, 1968; Wipf and Alefeld, 1974; Rowe et al, 1971). …”