Characterization of Amorphous Zr-Cu Alloy Surfaces by Electron Probe Microanalysis and Auger Electron Spectroscopy

摘要

The surfaces of an amorphous Zr-Cu alloys exposed to a laboratory air with the relative humidity of about 60 + - 10 percent at room temperature were studied by Auger electron spectroscopy (AES) aid scanning electron microscope, dipped with an energy dispersive X-ray analyzer (SEM/EDX). In general, the oxidation behavior of the -nil-side of the specimen which was in contact with the chilling wheel during quenching was different from that of the freely solidified surface. AES analysis of the specimen surfaces kept in a desiccator for 23 months unwed that the composition of the topmost region corresponded almost to ZrO_2. although some copper was also detected. Thickness of the surface film of ZrO_2 in the corrosion resistant region was about 4-5 nm, while that on die roll-side was smaller, especially in the region where a large amount of Cu was detected. Under the surface film, a large enrichment of Cu was estimated by non-destructive analysis of the AES data. The SEM/EDX observation of the cross-sections heavily corroded specimens clarified that the corrosion products consists of several layers of Cu-rich layers and Zr-rich layers which appear alternately. It is speculated that a metallic copper layer is formed under the surface film by preferential diffusion of Cu to the surface, which makes the ZrO_2 layer unstable and results to the break-down of the film.