Hydrogen-Induced Amorphization in C15 Laves Phase DyCo_2 Studied by Pressure Calorimetry

摘要

Structural changes in C15 Laves phase DyCo_2 on heating using a pressure differential scanning calorimeter (PDSC) in a hydrogen atmosphere between 0.1 and 5.0 MPa were investigated by a powder X-ray diffractometer (XRD), a differential scanning calorimeter under an argon flow atmosphere (Ar-DSC), a transmission electron microscope (TEM) and a hydrogen analyzer. As the temperature of DyCo_2 increases, the reactions such as hydrogen absorption in a crystalline state, HIA (hydrogen-induced amorphization), precipitation of DyH_3 and decomposition of the remaining amorphous phase into beta-Co + DyH_3 occurred exothermically for every hydrogen pressure. The mechanism of HIA in DyCo_2 is discussed on the basis of the experimental results.