Corrosion of nanocrystalline Ni–W alloys in alkaline and acidic 3.5 wt.% NaCl solutions

The corrosion behaviour of reverse-pulse electrodeposited nanocrystalline nickel tungsten alloys (nc Ni–W) in pH 3 and 10 3.5 wt.% NaCl solutions is investigated and analysed as a function of grain size. A potentiodynamic polarisation study reveals that the corrosion rate of nc Ni–W generally increases with the reduction of grain size in alkaline condition, but decreases with the reduction of grain size in acidic environment. Furthermore, for both environments, nc Ni–W alloys exhibit superior localised corrosion resistance than a microcrystalline Ni control specimen. Factors controlling the corrosion behaviour of these materials, including grain size, tungsten content, passivation and crystallographic texture are addressed.

Research highlights
► Investigation of corrosion behavior of nanocrystalline Ni-W alloys is conducted.
► Corrosion rate is higher in pH = 3 than in pH = 10 NaCl environments.
► Corrosion rate is controlled by W content in the acidic saline environment.
► In the alkaline condition, grain boundaries and texture control corrosion.
► Ni–W resists localized attack significantly better than microcrystalline Ni.