In-door atmospheric corrosion behavior of rapidly quenched amorphous Zr-Cu alloys

A series of amorphous Zr-Cu alloys prepared by means of rapid quenching were exposed to a laboratory air (RH = 60±10%, i.e. wet air) for 15 months and in a dessicator (RH ≤ 30%, i. e. dry air) for 23 months. The surface of alloys after exposure was examined by SEM/EDX, XRD and AES. The original surface film on the alloys consisted mainly of ZrO₂, and was protective. By exposure to the wet air, metallic copper and ZrO₂ were formed as corrosion products. The ZrO₂ formed on the Zr-Cu alloys was not in form of film and was not protective. The ZrO₂ formed was crystalline and mixture of monoclinic and tetragonal phases, the content of the latter phase increased with the increase in the alloy copper concentration. The surface film formed on the region in contact with the cooling wheel during quenching was rather unstable as compared with that formed on the freely solidified surface. Contaminants, such as C ℓ and S were often observed on the sites where corrosion started. The higher the copper content or the relative humidity, the larger was the corrosion rate.