Corrosion Behavior of Amorphous Nickel-Base Alloys in a Boiling Concentrated Sodium Hydroxide Solution

Polarization curves were measured in a boiling 50% NaOH solution, and the specimen surface was analyzed by X-ray photoelectron spectroscopy. A combined addition of chromium and molybdenum to amorphous nickel-phosphorus alloys significantly enhances the corrosion resistance. Addition of copper and lead are also effective in improving the corrosion resistance. The surface film formed on amorphous nickel-base alloys consists mainly of hydrated nickel oxyhydroxide. Chromium is concentrated in the alloy surface immediately under the surface film when nickel-base alloys containing chromium are immersed or polarized anodically at potentials close to the corrosion potential