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Abstract:
Amorphous Mg-based hydrogen-storage alloy (Mg70.6Ni29. 4)90Nd10 was prepared by melt-spinning. The phase structures of the ribbons before and after charge/discharge cycling were characterized by high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) analysis, respectively. It was found that the amorphous structure began to crystallize after four cycles of hydrogenation/ dehydrogenation and a new nano-crystallized phase NdMg2Ni9 was detected with average grain size in the range 5 nm. The nano-size Mg2Ni phases appeared after 6~10 cycles, and the stable Mg2Ni, α-Mg and Nd2H5 phases were present after 20 cycles of charging/discharging. That indicated that the NdMg2Ni9 phase formed at the beginning, also gradually decomposed into Mg2Ni, α-Mg and Nd2H5 phases as hydrogenation/dehydrogenation proceeded. The following results of thermodynamics calculation verified that the nano-crystallized phase NdMg2Ni9 was present firstly during the process of crystallization, because its free-energy (ΔG=-15. 2789 kJ·mol-1, T=300 K) was the lowest among Mg-Ni phase (ΔG=-8. 2694 kJ·mol-1, T=300 K) and Mg-Nd phase(ΔG=-13. 29503 kJ·mol-1, T=300 K).
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Zhongguo Xitu Xuebao/Journal of the Chinese Rare Earth Society
ISSN: 1000-4343
Year: 2010
Issue: 5
Volume: 28
Page: 575-581
Cited Count:
WoS CC Cited Count: 2
SCOPUS Cited Count:
ESI Highly Cited Papers on the List: 0 Unfold All
WanFang Cited Count:
Chinese Cited Count:
30 Days PV: 7
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