ORALS

SESSION: SISAMMonPM2-R5 H2-Storage Advanced Materials	Zehetbauer International Symposium on Science of Intelligent and Sustainable Advanced Materials (4th Intl. Symp. on Science of Intelligent and Sustainable Advanced Materials (SISAM))
Mon Nov, 5 2018 / Room: Copacabana A (150/1st)
Session Chairs: Zenji Horita; Christine Borchers; Session Monitor: TBA

15:55: [SISAMMonPM209] Keynote
Severe Plastic Deformation for Production of High-performance Hydrogen Storage Materials
Zenji Horita¹ ; ¹Kyushu University, Fukuoka, Japan;
Paper Id: 271 [Abstract]

High performance of hydrogen storage requires not only fast absorption/desorption kinetics but also lower operating temperature near ambient pressure. A process of severe plastic deformation through high-pressure torsion (HPT) was applied to two major hydrogen storage metallic materials such as Ti-based and Mg-based systems. Microstructures were well refined by the HPT process, so that nanograins were formed in the materials. For the Ti-based system, an HPT-processed TiFe intermetallic no longer requires pre-activation that limits practical use, as it involves exposure to hydrogen atmosphere under high pressures (>3 MPa) at high temperatures (~700 K). The lack of requirement for pre-activation is because hydrogen diffusion is enhanced through introduction of high densities of lattice defects such as grain boundaries [1]. Furthermore, the HPT-processed TiFe was not deactivated even after storage in air [2]. Application of the HPT process to Mg₂Ni made its hydrogen storage performance improved so that hydrogen absorption is feasible at a reduced temperature of 423 K with faster hydrogen kinetics. This was due to the introduction of high densities of planar lattice defects such as grain boundaries and stacking faults [3].

References:
[1] K. Edalati, J. Matsuda, H. Iwaoka, S. Toh, E. Akiba, Z. Horita, Int. J. Hydrogen Energy 38 (2013) 4622-4627.
[2] K. Edalati, J. Matsuda, M. Arita, T. Daio, E. Akiba, Z.Horita, Appl. Phys. Lett. 103 (2013) 143902.
[3] T. Hongo, K. Edalati, M. Arita, J. Matsuda, E. Akiba, Z. Horita, Acta Mater. 92 (2015) 46-54.