XPS and transmission electron microscopy of themulticomponent hydride-forming alloys

Abstract

The photoelectron spectrograms of the Ni2p, Ni3p, Co3p, Mn2p, Al2p,Ols and Cls in LaNi 4.6Mn 0.4, LaNi 4.5Al 0.5, MmNi 3.5Co 0.7Al 0.8, and Zr3d, Ti2p, V2p, Ni2p, Co2p, Ols, and Cls inZr 0.9VCo 0.55Ni 0.55 and Zr 0.59Ti 0.41V 0.53Cr 0.22 Fe 0.20Co 0.27Ni 0.78 have been obtained.In a surface layer about 2–2.5 nm of both alloys, the main part of nickel atoms are in metallic state(Ni 0) and only a third of them in oxidized state (Ni +2, Ni +3). At the same time the concentration of nickel in surface layer of Zr-containing alloy is muchlower as compared with Mm-containing alloy. The chemical state of Co and V atoms is similar toNi atoms state, but their concentrations, especially of V, in surface layer is lower than that ofnickel. The results of XPS have been compared with those of transmission electron microscopy ofthe thin foils of La- and Zr- based alloys. Dark field microphotographs of the oxidized alloysindicate presence of two different phases, which, according to electron microdiffraction, arenickel-based alloy and oxide. On the first stage of oxidation on the surface of foil the fine nickelparticles (about 10 nm) and amorphous oxide phase appear. Complete oxidation of the foil leadsto formation of eutectic-like structure of mixture of metallic and oxide phase. Some difference ofthe oxidized layer structure of investigated alloys have been observed.