Abstract
The corrosion behavior of amorphous Ni-15Cr-Ta-17P and Ni-38Cr-20Mo-10P alloys in a 63% P2O5 (87% H3PO4) solution at 433K was investigated. The corrosion rate of the Ni-15Cr-3Ta-17P alloy was about 0.109gh-1m-2 which was one order of magnitude as high as that of the crystalline tantalum metal. The surface film was composed of a high concentration of phosphate and the significant deficiency of nickel took place in both the surface film and the underlying alloy surface. The amorphous Ni-38Cr-24Mo-10P alloy passivated spontaneously and its corrosion rate was about 0.040gh-1m-2. The passive film on the spontaneously passive alloy consisted mainly of hydrated oxyhydroxide of chromium and molybdenum, and the composition of the underlying alloy surface was not greatly different from the bulk alloy composition.
