Impact of Substitution of M (M=Mn, Cu) for Ni on Hydriding and Dehydriding Kinetics of as-Spun Nanocrystalline and Amorphous Mg<sub>2</sub>Ni-Type Alloys

Abstract

The Ni was partially substituted by M (M=Co, Cu) in order to ameliorate the hydriding and dehydriding kinetics of Mg2Ni-type alloy. The melt spinning technology was used to prepare the Mg20Ni10-xMx (M=Mn, Cu; x=0, 1, 2, 3, 4) alloys. The structures of the as-spun alloys were characterized by XRD and TEM. The hydriding and dehydriding kinetics of the alloys were measured by an automatically controlled Sieverts apparatus. The results show that the as-spun (M=Mn) alloys hold a nanocrystalline and amorphous structure, whereas the as-spun (M=Cu) alloys display an entire nanocrystalline structure, indicating that the substitution of Mn for Ni facilitates the glass formation in the Mg2Ni-type alloy. Additionally, Mn substitution incurs the formation of secondary phases MnNi and Mg instead of changing the Mg2Ni major phase. The hydriding kinetics of the as-spun alloys first mounts up and then declines with the rising of M (M= Mn, Cu) content, whereas the substitution of M (M=Mn, Cu) for Ni enhances the dehydriding kinetics of the alloy dramatically.