Pitting corrosion of ZrNi5−xCox alloys in alkaline solution

The paper presents research of the pitting corrosion of a series of ZrNi5−xCox-type alloys in alkaline solution (pH=13) containing 0.5 M Cl− ions. In the absence of chloride ions the tested alloys passivate spontaneously and show a good corrosion resistance. Substitution of nickel by increasing amounts of cobalt in the ZrNi5 intermetallic compound promotes pit nucleation in the presence of chloride ions. The presence of cobalt in the alloys inhibits, however, the progress of pitting corrosion.