An auger electron spectroscopic study of the corrosion behavior of an amorphous Zr 40Cu 60 alloy

Abstract

The corrosion behavior of an amorphous Zr 40Cu 60 alloy in laboratory air (RH = 60 ± 10%) at room temperature was studied by grazing incidence X-ray diffraction (GIXRD) and Auger electron spectroscopy (AES) combined with Ar ion sputter-etching. In general, the corrosion behavior of the roll-side of the specimen which was in contact with the chilling roll during quenching was different from that of the freely solidified surface (top-side). The GIXRD data suggested that monoclinic ZrO 2 ( m-ZrO 2) and tetragonal ZrO 2 ( t-ZrO 2) were formed under a surface layer of metallic copper which was also formed by corrosion of alloy. The t-ZrO 2 was distributed more deeply than the m-ZrO 2. By AES, it was clarified that a metallic copper layer covered with a very thin ZrO 2 was placed in the topmost region, and that, under the copper layer on the roll-side surface, a sandwich structure of ZrO 2 and metallic copper was formed, i.e. the corroded region consisted of several layers of ZrO 2-rich and copper-rich layers distributed alternatively. On the top side, however, the oxidized layer did not develop significantly and the sandwiched structure of ZrO 2 and metallic copper was not observed.