Hydrogen Diffusivity and Permeability In Pd50-xTi50(Cr, Fe)x Alloys

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Hydrogen diffusivity (D) and permeability (q) in Pd50-xTi50(Cr, Fe)x alloys were measured at temperature range between 570 and 770 K. During a heating measurement of Pd47Ti50Cr3 alloy, both D and q abruptly increased by factors of 5 and 2, respectively, at 712 K, with a phase transformation from B19 to B2 structures. However, q was far smaller than those in pure bcc metals (eg. V, Nb and Ta), where the hydrogen atoms occupy the tetrahedral interstitial sites. A first-principles calculation revealed that hydrogen atoms occupy the octahedral interstitial sites in Pd50Ti50 with B2 structure. It is concluded that the small hydrogen diffusivity in B2 Pd50-xTi50(Cr, Fe)x alloys is due to the long distance hydrogen jump and the resultant high activation energy for the diffusion.

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Periodical:

Materials Science Forum (Volumes 561-565)

Main Theme:

Edited by:

Young Won Chang, Nack J. Kim and Chong Soo Lee

Pages:

2353-2356

Citation:

O. Yoshinari and D. Itoh, "Hydrogen Diffusivity and Permeability In Pd50-xTi50(Cr, Fe)x Alloys", Materials Science Forum, Vols. 561-565, pp. 2353-2356, 2007

Online since:

October 2007

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$38.00

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DOI: https://doi.org/10.1016/s0360-3199(01)00139-2

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[1] 2 H Fig. 3 Hydrogen adiabatic potential on (001) plane of PdTi B2-phase. Contour lines are drawn with a separation of 0. 05 eV.

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