Structural changes in the Ni2Y-H system, as a function of hydriding temperature and time under a H pressure of 1MPa, were monitored by means of X-ray diffractometry and thermal analysis. It was demonstrated that the amorphization reaction for hydriding at 473K was much delayed in comparison with that at 573 or 273K. This temperature dependence of the formation rate of the amorphous phase could be explained qualitatively by invoking 2 accelerating factors for Ni diffusion. These were a lattice expansion due to H absorption, and thermal activation. It was also noted that Y-rich tetrahedral sites increased with increasing hydriding temperature and time. In particular, when the hydriding temperature was high enough, Y-rich sites in the amorphous phase sharply increased in number.

S.Yoshioka, S.Orimo, H.Fujii: Journal of the Japan Institute of Metals, 1996, 60[1], 16-21