To explore the amorphization mechanism of Zr-based alloys hydrogen induced amorphization behaviors of $Zr_2Al$($Ni_2In$ type, hexagonal structure) are investigated by means of XRD, TEM, DTA. To examine the atomic size effects or the amorphization behaviors, Ti substitute for Zr.
At low hydrogenated temperature, the $Zr_2Al$ and $(Zr,Ti)_2Al$ compounds form crystalline hydrides(orthorhombic structure) initally and transform to amorphous phases. At high hydrogenated temperature, the amorphous hydrides decompose into stable phases. The amorphization temperature is increased by the Ti substitution, which is considered due to the decrease of the unit cell volume owing to the substitution.
It is suggested that the hydrogen-induced amorphization occures as a result of the suppression of the decomposition of the crystalline hydride $(Zr_2AlH_x)$ into stable phases $(ZrH_2+Zr_3Al_2)$, and the amorphization mechanism is the motion of Al atoms in the short range.
