Influence of hydrogen dopant on the structure and crystallization of the partially crystalline Zr76Ni24 metallic glass

The influence of hydrogen dopant on the structure and crystallization of partially crystalline Zr76Ni24 metallic glass during heat treatment at different heating rates has been investigated by means of differential scanning calorimetry (DSC) in the temperature interval from 300 to 823 K and by X-ray powder diffraction (XRD) at room temperature. According to the XRD results, the as quenched Zr76Ni24 samples were mostly glassy (about 90%) with about 10% orthorhombic metastable Zr3Ni crystalline phase. A systematic DSC analysis shows that adding hydrogen to these Zr76Ni24 samples raises the temperature of crystallization, T-x1 for the hydrogen content up to x = 0.054 (x indicate at.%). Also, the hydrogen absorption causes an increase of the lattice parameter a and a decrease of the lattice parameter b of the orthorhombic metastable Zr3Ni crystalline phase. The as quenched Zr76Ni24 samples showed to be oxidation resistant, whereas the oxidation rate of the hydrogen doped sample increases with increasing hydrogen content during heat treatment up to 823 K. The scales formed on the surface of the annealed hydrogen doped samples during the oxidation have a nanocrystalline microstructure consisting mainly of monoclinic ZrO2. (C) 2004 Elsevier B.V. All rights reserved.