Mg81Ni19-8wt.% REO (oxides of Lanthanum and Cerium) alloys were successfully prepared using mechanical alloying method with Mg-Ni alloy and REO powder. Phase analysis, structural characterization, and microstructure imagine of the alloys were conducted using X-ray diffraction (XRD), metallurgical microscope, and transmission electron microscopy (TEM) methods. Multi-phase structures, including the primary phase of Mg2Ni and several secondary phases of Mg + Mg2Ni, MgNi-LaO, and MgNi-CeO, were found in in the as-cast Mg81Ni19- 8wt.% REO alloys. XRD and TEM results showed that Ce exhibits variable valence behavior at various stages, and the addition of REO promotes the nanocrystalline of the alloy. The hydrogen absorption capacity of ball-milled Mg81Ni19 and Mg81Ni19- 8wt.%REO alloy for 2 h at 343 K is 1.34 wt.% and 1.83 wt.%, which are much larger than 0.94 wt.% of as-cast Mg81Ni19 alloy. The addition of REO led to a decrease of the thermal decomposition temperature of the alloy hydride by approximately 20 K and a reduction of the activation energy of the hydrogen desorption reaction by 10% and 13%, respectively.

Microstructure characteristics and hydrogen storage kinetic of nano MgNi-REO alloys
    Abstract
    1 Introduction
    2 Experimental
        2.1 Material preparation methods
        2.2 Structural characterizations
        2.3 Hydrogen storage measurements
    3 Results and discussion
        3.1 Structure and morphology characterizations
        3.2 Hydrogen absorption and desorption kinetics
        3.3 Thermodynamic properties
    4 Conclusion
    Acknowledgements 
    References

• Hongxiao Tian(School of Science, Inner Mongolia University of Science and Technology, Baotou 014010, China)
• Xinghu Yan(Key Laboratory of Integrated Exploitation of Baiyun Obo Multi‑Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010, China)
• Xia Li(School of Science, Inner Mongolia University of Science and Technology, Baotou 014010, China)
• Feng Hu(School of Science, Inner Mongolia University of Science and Technology, Baotou 014010, China)
• Yongzhi Li(School of Science, Inner Mongolia University of Science and Technology, Baotou 014010, China, Baotou Materials Research Institute of Shanghai Jiao Tong University, Baotou 014010, China)
• Zengwu Zhao(Key Laboratory of Integrated Exploitation of Baiyun Obo Multi‑Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010, China)