Effect of structural changes on degradation of hydrogen absorbing capacity in cyclically hydrogenated TiMn2 based alloys

• Published in: Journal of alloys and compounds Vol. 376; no. 1-2; pp. 232 - 240
• Main Authors: SEMBOSHI, Satoshi, SAKURAI, Masaki, MASAHASHI, Naoya, KONNO, Toyohiko J, HANADA, Shuji
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier 11.08.2004
• Subjects: Applied sciences; Chemical and electrochemical properties; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Materials and auxiliary equipments used in energy engineering; Metals. Metallurgy; Titanium alloy; Manganèse alloy; Hydrogen storage; X-ray absorption fine-structure (XAFS); Hydrides; Nanostructure; Hydrogenation; TiMn2 alloys; Fine structure; Phase transformation; Absorption; X-ray absorption spectra; Hydrogen additions; Laves phase; Hydride; Microstructure
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2003.12.044

Structural changes of cyclically hydrogenated TiMn2 based alloys, in which the compositions of the TiMn2 Laves phase are about 60 and 61 at.% Mn, have been investigated to understand the mechanism of the degradation of their hydrogen absorbing capacity. There are no apparent changes in micro- and nano-scale metallurgical features in the Ti-60at.% Mn alloy, which exhibited superior endurance cyclic property. On the contrary, hydride formation, decrease in crystalline size and/or introduction of heterogeneous strain, and the deviation of Mn atom position have been observed in Ti-61 at.% Mn alloy, which exhibited poor cycle property, arising from retained hydrogen in the TiMn2 Laves phase. Therefore, it is considered that structural changes with cyclic hydrogenation sensitively depend on the composition of TiMn2 Laves phase, governing the degradation behavior. The mechanism of the degradation of cyclic property is discussed in view of the substitution behavior in the hexagonal TiMn2 Laves phase.