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Effect of Al* generated in situ in hydriding on the dehydriding properties of Mg-Al alloys prepared by hydriding combustion synthesis and mechanical milling.
- Source :
-
Journal of Alloys & Compounds . Jun2018, Vol. 750, p490-498. 9p. - Publication Year :
- 2018
-
Abstract
- In this work, the effects of Al* generated in situ in hydriding on the dehydriding of Mg-Al alloys prepared by Hydriding Combustion Synthesis (HCS) and Mechanical Milling (MM) were studied. Thermal analysis showed that the peak dehydriding temperature of MgH 2 was reduced by 25 °C (or 11 °C) when 20 at% Al was added in HCS (or MM) process, even though, the same dehydriding reaction of 17MgH 2 + 12Al*/Al → Al 12 Mg 17 + 17H 2 was observed. Isothermal dehydriding at 300 °C for 3 h demonstrated that it took 81 min for HCS+MM-MgH 2 to desorb 50% of hydrogen, while only 24 min was required for HCS+MM-Mg 80 Al* 20 . The apparent activation energy for dehydriding of MgH 2 was reduced from 144.3 ± 7.19 kJ/mol for HCS+MM-MgH 2 to 118.8 ± 6.73 kJ/mol for HCS+MM-Mg 90 Al* 10 . The scanning electron microscopy/energy dispersive spectroscopy and X-ray photoelectron spectroscopy analyses revealed that the Al* in situ generated from the hydriding of Al 12 Mg 17 in HCS would significantly decrease dehydriding temperature and improve dehydriding kinetics of the MgH 2 -Al composites because of a uniform distribution, the shortening reaction diffusion length, providing unoxidized surfaces to react with MgH 2 and the high chemical activity of Al*. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 09258388
- Volume :
- 750
- Database :
- Academic Search Index
- Journal :
- Journal of Alloys & Compounds
- Publication Type :
- Academic Journal
- Accession number :
- 129273192
- Full Text :
- https://doi.org/10.1016/j.jallcom.2018.04.023