XPS and transmission electron microscopy of the multicomponent hydride-forming alloys

The photoelectron spectrograms of the Ni2p, Ni3p, Co3p, Mn2p, Al2p, Ols and Cls in LaNi4.6Mn0.4, LaNi4.5Al0.5, MmNi(3.5)Co(0.7)Al(0.8), and Zr3d, Ti2p , V2p, Ni2p, Co2p, Ols, and Cls in Zr0.9VCo0.55Ni0.55 and Zr0.59Ti0.41V0.53 Cr0.22 Fe0.20Co0.27Ni0.78 have been obtained. In a surface layer about 2-2. 5 nm of both alloys, the main part of nickel atoms an in metallic state (Ni -0) and only a third of them in oxidized state (Ni+2, Ni+3). At the same ti me the concentration of nickel in surface layer of Zr-containing alloy is m uch lower as compared with Mm-containing alloy. The chemical state of Co an d V atoms is similar to Ni atoms state, but their concentrations, especiall y of V, in surface layer is lower than that of nickel. The results of XPS h ave been compared with those of transmission electron microscopy of the thi n foils of La- and Zr- based alloys. Dark field microphotographs of the oxi dized alloys indicate presence of two different phases, which, according to electron microdiffraction, are nickel-based alloy and oxide. On the first stage of oxidation on the surface of foil the fine nickel particles (about 10 nm) and amorphous oxide phase appear. Complete oxidation of the foil lea ds to formation of eutectic-like structure of mixture of metallic and oxide phase. Some difference of the oxidized layer structure of investigated all oys have been observed. (C) 1999 International Association for Hydrogen Ene rgy. Published by Elsevier Science Ltd. All rights reserved.