Tomonori Nambu1, Nobue Shimizu1,, Hisakazu Ezaki1, Hiroshi Yukawa2, Masahiko Morinaga2 and Nobuhiko Takeichi3
1Department of Materials Science and Engineering, Suzuka National College of Technology, Suzuka 510-0294
The Lattice constants of pure niobium metal were measured by in-situ X-ray diffraction method at the temperature of 293 K to 673 K and the hydrogen pressure below 0.3 MPa. The deformation and fracture of niobium metal membrane during hydrogen permeation were treated by the measured lattice strain. The membrane was deformed and fractured easily when about 10% lattice contraction was introduced to it by lowering the hydrogen pressure at 673 K, at which the dehydrogenation reaction progressed smoothly. However, neither deformation nor fracture took place at the temperature lower than 473 K, because the dehydrogenation reaction hardly occurred in such a temperature range. Thus, the principal reason for the deformation or fracture of niobium metal membrane was attributable to the large volumetric contraction during dehydrogenation, the easiness of which, however, depended largely on the temperature.
lattice constant, volumetric strain, niobium, niobium hydride, hydrogen permeation, X-ray diffraction
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