Hydrogen induced amorphization of LaMgNi4 phase in metal hydride alloys
Leonid A. Bendersky, Haoting Shen, Kwo Young, Taihei Ouchi
Hydrogen induced amorphization (HIA) of the LaMgNi4 phase at 30C was found in three LaMgNi4/LaNi5 two-phase metal hydride (MH)-forming alloys. The amorphization happened at the first dehydrogenation cycle from a fully hydrided alloy, and the process is reversible after annealing at 250C for 1 h. The hydrogen storage capacity of the LaMgNi4 phase in an amorphous state is higher than in its crystalline form. A scanning electron microscope study did not observe any significant changes in the shape of grains as a consequence of HIA and re-crystallization. A transmission electron microscope study confirmed the amorphous structure of the LaMgNi4 phase after HIA. These findings suggest a new way to improve the performance of MH alloys when used in electrochemical applications.