Effect of mechanical alloying conditions on the microstructure evolution and electrode characteristics of Mg63Ni30Y7

Mg63Ni30Y7 alloy powders were produced by means of mechanical alloying. The alloying conditions were optimized so that alloys with an amorphous or a nanocrystalline-amorphous microstructure were obtained. The chemical composition, microstructure, morphology and thermal stability of the mechanically alloyed powders were studied. On the basis of these produced alloy powders, hydride electrodes were fabricated and their electrochemical behavior in 6 M KOH was investigated. The alloys with mixed nanocrystalline-amorphous microstructure prepared under use of a SPEX shaker mill and more considerable fraction of nanocrystals reveal a higher electrochemical activity for hydrogen reduction at cathodic potentials and a higher maximum discharge capacity (247 mAh/g) than the alloys with predominantly amorphous microstructure (216 mAh/g) obtained when using a Retsch planetary ball mill at lowered temperatures.