Effect of microstructure on the properties of Zr-Mn-V-Ni AB, type hydride electrode alloys

The effect of the microstructure for multicomponent ZrMn0.9-xVxNi1.1 (x = 0 .1-0.8) hydride electrode alloys on their hydrogen absorbing capacity, acti vation and high rate discharge capacity was investigated. The electrochemic al properties and microstructure changed with the alloys compositions. The microstructure were determined by the combination of transmission electron microscopy (TEM) and X-ray Rietveld analysis. Hexagonal C14 type, cubic C15 type Laves phase and tetragonal body centered Zr9Ni11 coexisted in the all oys of given compositions. The metastable Zr9Ni11 phase was stabilized at r oom temperature as long range ordered state along [100] and [010] direction s. Substructure of each phase and the orientation relations among the exist ing phases were investigated in detail. Stacking faults in the C15 Laves ph ase and precipitation of Zr-Ni binaries considerably enhanced the activatio n and high rate discharge capacity of Laves phase. (C) 1999 International A ssociation for Hydrogen Energy. Published by Elsevier Science Ltd. All righ ts reserved.