Electrochemical corrosion characteristics of ZrNi5−xCox alloys

Abstract The electrochemical corrosion behaviour of a series of ZrNi 5− x Co x alloys with x =0–4 has been tested using potentiokinetic polarisation technique. The polarisation curves were measured in deaerated 0.5 M sulphate solutions with pH=0.2–7 and in strong alkaline solution of KOH (pH=15). It is shown that the presence of greater amounts of Co in the alloy ( x ⩾2) worsens the passivating properties of the alloy in acidified sulphate solutions. On the other hand, in strong alkaline solutions, both low- and high-cobalt alloys undergo stable passivation. The degree of Ni substitution by Co in the alloys does not generally affect the shape of cathodic polarisation curves.