Oxidation behavior of amorphous Ni-Zr and Ni-Zr-Sm alloys

In order to control the: oxidation products of amorphous Ni-Zr and Ni-Zr-rare earth clement alloys, which have an important role in the catalytic activity of amorphous alloy-derived catalysts, their oxidation behavior was examined as a function of nickel and samarium contents. Faster oxidation occurs for the nickel-rich Ni-Zr binary alloys compared with the zirconium-rich alloys. The addition of samarium further accelerates the oxidation. due to thr formation of a poorly protective oxide scale. The: oxides formed from amorphous Ni-Zr and Ni-Zr-Sm alloys are nanograined zirconia as well as NiO. The zirconia consists of metastable tetragonal and monoclinic phases. The relative amount of the tetragonal phase increases with an increase in the alloy nickel content. The suppression of grain growth of zirconia by the fine dispersion of NiO results in the formation of the metastable tetragonal phase. The addition of samarium to the Ni-Zr alloys further promotes the formation of the tetragonal phase as a result of the stabilization of the tetragonal phase by doping of samarium ions. (C) 2000 The Electrochemical Society. S0013-4651(00)04-067-2. All rights reserved.