AMORPHIZATION OF RFE2 LAVES PHASES BY HYDROGEN ABSORPTION

By hydrogenation of Laves phase RFe2 compounds (where R is yttrium, samarium, gadolinium, terbium, dysprosium, holmium or erbium) between 450 and 550 K, we demonstrate that it is possible to produce the amorphous alloys containing hydrogen. The amorphous nature of the samples was confirmed by both X-ray diffraction and transmission electron microscopy. The RFe2 compounds absorb hydrogen in the crystalline state below 450 K, and they decompose into elemental hydride RH2 and α-Fe above 550 K. Only CeFe2 transforms to the amorphous state below 550 K, and decomposes into CeH2 and α-Fe above 550 K. Based on the experimental results, we suggest that hydrogen-induced amorphization occurs as a result of the suppression of the decomposition of the RFe2 compounds into RH2 and α-Fe.