The synthesis and hydrogen storage properties of Mg 2 Ni substituted with Cu, Co
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The synthesis and hydrogen storage properties of Mg2Ni substituted with Cu, Co Yu’an Chena) College of Materials Science and Engineering, Chongqing University, Chongqing 400044, People’s Republic of China; and National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044, People’s Republic of China
Hua Huang,b) Jie Fu, and Qing Guo College of Materials Science and Engineering, Chongqing University, Chongqing 400044, People’s Republic of China
Fusheng Pan College of Materials Science and Engineering, Chongqing University, Chongqing 400044, People’s Republic of China; and National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044, People’s Republic of China
Shiping Deng, Jiaming Li, and Guangming Zhao Chongqing Instrument Materials Research Institute, Chongqing 400700, People’s Republic of China (Received 7 August 2008; accepted 15 December 2008)
Mg2Ni1-xCux (x = 0, 0.2, 0.4) and Mg2Ni1-yCoy (y = 0, 0.2, 0.4) were successfully synthesized via two steps: induction melting and then ball milling. The component and microstructure of the alloys were determined with x-ray diffraction (XRD) and scanning electron microscopy/x-ray energy-dispersive spectrometry (SEM/XEDS). Mg2Ni phase was observed in all 5 alloys. When the amount of Cu was increased, it led to the formation of phase from Mg2Cu to Cu11Mg10Ni9. Co2Mg was detected in the Co-containing alloys. The hydrogen absorption/desorption properties were tested with p-C-T measurement apparatus, and the results showed that the gaseous storage properties of the alloys were improved by the addition of Cu or Co. I. INTRODUCTION
Mg-based hydrogen storage alloys have been considered as attractive hydrogen-storage materials because of their high hydrogen storage capacity, light weight, and low cost. However, the slow desorption kinetics and high thermodynamic stability of the materials restrict them from actual applications. Novel synthesis methods, addition of a small amount of substitutional elements, and surface treatment can significantly improve the hydrogen storage properties of Mg-based hydrogen storage alloys. For example, hydriding/ dehydriding temperature of Mg-Ni alloy was decreased by addition of Al, V, or Mn.1,2 Mg2Ni did not absorb hydrogen at 200 C without ball milling. After ball Address all correspondence to this author. a) e-mail: [email protected] b) e-mail: [email protected] This paper was selected as an Outstanding Symposium Paper for the 2008 International Materials Research Conference, Symposium H. DOI: 10.1557/JMR.2009.0177 J. Mater. Res., Vol. 24, No. 4, Apr 2009
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milling, nano-Mg2Ni was obtained and its hydrogen capacity was 3.4% at 200 C.3 The cycle life of the alloys in the electrochemical test was increased by replacing Mg with Ti, Al, Co, Ce, or Cr, respectively.4–6 Mg-Ce alloy was prepared by induction melting under vacuum and then mechanically pulverized. The alloy showed significant hydriding/dehydriding perform
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