Hydrogen permeability of the Nb40Ti30Ni30 alloy with anisotropic microstructures produced by hot working

作者：Tokui Sho^*; Ishikawa Kazuhiro; Aoki Kiyoshi

来源：Journal of the Japan Institute of Metals, 2007, 71(2): 176-180.

DOI：10.2320/jinstmet.71.176

• hydrogen permeation
• hydrogen purification
• intermetallic compound
• duplex phase
• microstructure control
• anisotropic microstructure

The relation between microstructure and hydrogen permeability (Phi) of the Nb40Ti30Ni30 alloy after hot-forging and hot-rolling and subsequent annealing treatments has been investigated in order to develop highly hydrogen permeable microstructures. By hot forging and rolling at 1173 K, the primary (Nb, Ti). phase is elongated along the rolling direction (RD), while it is compressively deformed in the normal direction (ND). Thus, anisotropic microstructures can be formed by the hot working technique. Phi(673 K) of the hot worked sample measured along to RD is 4.4 x 10(-8) [mol H(2)m(-1) s(-1) Pa-(1/2)] at 673 K, which is 2.5 times higher than that of as-cast one. On the other hand, Phi(673 K) of the hot worked sample measured along to ND is 0.5 x 10(-8) [mol H-2 m(-1) s(-1) Pa-(1/2)], which is 1/3 of that of as-cast one. Phi(673 K) of the RD sample increases with increasing annealing time and attains to 7.4 x 10(-8) [mol H(2)m(-1) s(-1) Pa-(1/2)] by annealing for 360 ks at 1373 K, which is 3 times higher than that of Pd-25 mass%Ag. Even though fine lamellar eutectic {TiNi + (Nb, Ti)} structure disappears and is replaced by the spherical (Nb, Ti) phase which is embedded in the TiNi matrix, the large resistance to the hydrogen embrittlement is kept. The present work clearly demonstrates that microstructural control of the Nb40Ti30Ni30 alloy using hot working and subsequent heat treatments are effective for development of microstructures showing high Phi without the loss of resistance to the hydrogen embrittlement.

• 出版日期2007-2