Effect of microstructure on the phase composition and hydrogen absorption-desorption behaviour of melt-spun Mg-20Ni-8Mm alloys
Wu, Y.
,
Lototsky, M.V.
,
Solberg, J.K.
,
Yartys, V.A.
International Conference on Clean Energy, 10, Famagusta /Kypros), 2010-09-15--09-17.
International journal of hydrogen energy,
Vol. 37, no 2 (January 2012), 1495–1508
- Publ. year
- 2012
- Publ. type
- article , paper
- Abstract
- The effect of microstructure on the phase composition and hydrogen absorption-desorption behaviour of Mg-based Mg-20Ni-8Mm (wt.%) (Mm = La-rich Mischmetal) alloys has been studied. Rapid solidification (RS) processing resulted in the formation of the high-temperature cubic modification of Mg2NiH4 and the solid solution hydride Mg2NiH0.3, in the disappearance of the monoclinic modification of Mg2NiH4, as well as in a decrease in the unit cell volumes of the constituent hydride phases. The above-mentioned tendencies became more pronounced in the order “as-cast < Cu-300 < Cu-1000 ≈ Cu-2000” (where the sample names Cu-#### denote the spinning velocity of the copper wheel in rpm), which is explained by an increase in the mechanical stresses in the materials and/or by an increased interfacial energy of the fine grains of the corresponding hydrides. The hydrogen absorption kinetics was improved in the order “Cu-300 < Cu-1000 < Cu-2000”. The temperature range of hydrogen thermal desorption from the hydrogenated alloys shrank in the order “Cu-300 > Cu-1000 >> Cu-2000”, which is explained by increased uniformity of the hydrides grain size in the hydrides with increasing solidification rate. During PCT (pressure composition temperature) tests, the Cu-1000 and Cu-2000 samples displayed the largest pressure hysteresis and the smallest slope of the higher Mg2NiH4 plateau, but also the lowest hydrogen storage capacity.
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