Hydriding and Dehydriding Kinetics of Nanocrystalline and Amorphous Mg₂₀Ni₆M₄ (M=Cu, Co) Alloys

Abstract:

It was well known that the Mg₂Ni-type alloy with a nanocrystalline/amorphous structure possesses superior hydrogen storage kinetics. In order to obtain a nanocrystalline and amorphous structure, the melt spinning was applied to prepare the Mg₂Ni-type Mg₂₀Ni₆M₄ (M=Cu, Co) hydrogen storage alloys. The microstructures of the as-cast and spun alloys were characterized by XRD, SEM and HRTEM. The gaseous hydriding and dehydriding kinetics of the alloys was measured. The results show that the as-spun (M=Co) alloys display a nanocrystalline and amorphous structure as spinning rate approaches to 20 m/s, while the as-spun (M=Cu) alloys hold an entire nanocrystalline structure whatever spinning rate is, suggesting that the substitution of Co for Ni facilitates the glass formation in the Mg2Ni-type alloy. The melt spinning markedly improves the gaseous hydrogen storage kinetics of the alloys. As the spinning rate grows from 0 (as-cast was defined as the spinning rate of 0 m/s) to 30 m/s, the hydrogen absorption saturation ratio ( ) is enhanced from 57.7% to 91.4% for the (M=Cu) alloy and from 77.1% to 93.5% for the (M=Co) alloy. And hydrogen desorption ratio ( ) is raised from 28.7% to 59.0% for the (M=Cu) alloy and from 54.5% to 70.2% for the (M=Co) alloy, respectively.

• Periodical: Advanced Materials Research (Volumes 512-515)
• Pages: 1389-1394
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.512-515.1389
• Online since: May 2012
• Authors: Yang Huan Zhang, Guo Fang Zhang, Hong Wei Shang, Zhong Hui Hou, Ying Cai, Dong Liang Zhao
• Keywords: Hydriding and Dehydriding Kinetics, Melt Spinning, Mg₂Ni-Type Alloy, Structure

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