Effects of Rapid Quenching on Structure and Hydrogen Storage Characteristics of Mg20Ni10-xMnx (x=0-4) Alloys

In order to improve the hydrogen storage characteristics of the Mg2Ni-type alloys, Ni in the alloy was partially substituted by Mn. Rapid quenching technology was used to prepare the Mg20Ni10-xMnx (x=0, 1, 2, 3, 4) hydrogen storage alloys. The microstructures of the as-cast and quenched alloys were characterized by XRD and HRTEM. The hydriding and dehydriding kinetics of the alloys were measured by an automatically controlled Sieverts apparatus. The electrochemical performances were tested by an automatic galvanostatic system. The results show that, as the quenching rate reaches to 20 m/s, an amorphous phase can be detected in the (x=4) alloy, and the amorphization degree of the alloy visibly increases with the growing of the quenching rate. The rapid quenching improves the hydrogen absorption and desorption characteristics of the alloy dramatically. Additionally, it also enhances the electrochemical hydrogen storage performances greatly, including the discharge capacity and cycle stability of the alloys substituted by Mn.