LightMAT 2021
Lecture
02.11.2021 (CET)
Hydrogen Storage Properties of Mg-Alloys As-Processed By SPD
MZProf. Dr. Michael Zehetbauer
Zehetbauer, M. (Speaker)¹; Abbasi, Z.²; Cengeri, P.¹; Enzinger, N.³; Fujii, H.⁴; Kimoto, Y.⁵; Krexner, G.¹; Morisada, Y.⁴; Schafler, E.¹; Sommitsch, C.³
¹Univ. Vienna, Wien, Austria; ²School of Engineering, Shiraz Univ., Shiraz, Iran; Faculty of Physics, Univ.Vienna, Wien, Austria; ³Inst. Materials Science, Joining and Forming, Graz Univ.Technology, Graz, Austria; ⁴Osaka Research Inst. Industrial Science and Technology, Osaka, Japan; ⁵Joining and Welding Research Inst., Osaka Univ., Osaka, Japan
Hydrogen is a promising energy carrier in view of its energy density considerably exceeding that of current batteries [1]. Safe and efficient hydrogen storage can be achieved in solid materials especially in nanocrystalline metals and alloys. While so far only grain boundaries have been known for increasing the kinetics through enhanced hydrogen diffusion [2], current research on light metal–hydrogen systems showed that processing methods of SPD (Severe Plastic Deformation) like Equal Channel Angular Pressing (ECAP) and High Pressure Torsion (HPT) [3-6] can noticeably enhance the kinetics of absorption/desorption. The reason for this behavior is the high extent of plastic strain achieved by SPD which leads to significantly higher densities of lattice defects not only of grain boundaries, but also dislocations and mainly vacancy agglomerates. The latter exhibit the largest specific free volume of all lattice defects which makes them most effective in trapping the hydrogen atoms and acting as nuclei for the hydride formation [3-6]. Comparison with the storage performance of pure Mg reveals that the thermal sustainability of vacancy-type defects is another condition to enable the desired high-cycle stability of storage material. Further experiments showed that the suggested mechanisms not only apply for HPT but also Friction Stir Processing (FSP) which – because of its multidirectional deformation characteristics - provides extreme generation of vacancy-type defects and thus very good performance of both hydrogen storage kinetics and hydrogen storage capacity.
[1] M. Fichtner, Nanostr.Mater., p. 270, G. Wilde Ed., Elsevier Ltd., Oxford, UK (2009)
[2] S. Divinski, G. Wilde, J.Alloys Comp..464, 374 (2008)
[3] T.Hongo, K.Edalati, M.Arita, J. Matsuda, E. Akiba, Z. Horita, Acta Mater. 92, 46 (2015)
[4] A. Grill, J. Horky, A. Panigrahi, G. Krexner, Int.J.Hydr.Energy 40, 17144 (2015)
[5] D. Setman, M. Krystian, M. J. Zehetbauer, Mater.Sci. Forum 584-586, 355 (2008)
[6] M. Krystian, D. Setman, B. Mingler, G. Krexner, M. J. Zehetbauer, Scr.Mater.62, 49 (2010)
Abstract
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