日本金属学会誌

J. Japan Inst. Metals, Vol. 70, No. 1 (2006),
pp. 80-88

Deformation and Fracture Modes of Hydrogen Permeable Membrane of Pure Niobium in Highly Soluble Hydrogen State

Tomonori Nambu1, Nobue Shimizu1,, Hisakazu Ezaki1, Hiroshi Yukawa2 and Masahiko Morinaga2

1Department of Materials Science and Engineering, Suzuka National College of Technology, Suzuka 510-0294
2Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya University, Nagoya 464-8603

Abstract:

The deformation and fracture modes of pure niobium metal membrane were investigated by a series of hydrogen permeation tests in a highly soluble hydrogen state. The membrane underwent a large plastic deformation due to the lattice expansion and contraction during hydrogenation and dehydrogenation. A crack initiated on the membrane surface under the tensile stress condition, but not under the compressive stress condition. All the fractured sections in the membrane showed the characteristics of quasi-cleavage fracture. However, even in the case of a large amount of hydrogen dissolved into the membrane, it never fractured as far as hydrogen keeps permeating through the membrane at a constant temperature and a constant hydrogen pressure difference between inlet and outlet surfaces. In other words, brittle fracture of pure niobium metal membrane was not caused by the amount of dissolved hydrogen, but by either a rapid change in the hydrogen density in the membrane or a continuous hydrogen dissolution reaction in progress into it.


(Received 2005/9/20)

Keywords:

niobium membrane, hydrogen embrittlement, hydrogen solubility, plastic deformation


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