Electrochemical Behavior of Nickel-Aluminum Alloys in Sodium Chloride Solutions
The anodic and cathodic reactions involved in the corrosion process on several nickel-aluminum alloys including two intermetallic compounds NiAl and Ni3Al in the NaCl solutions are studied. A procedure of pretreatment of test specimens and measuring the anodic and cathodic voltammograms is developed. It enabled us to obtain reproducible results including Tafel portions of voltammograms. The corrosion potentials Ecorr and corrosion currents icorr are determined by the coordinates of the intersection of anodic and cathodic Tafel plots. The dependences of Ecorr and icorr on the alloy composition (the content of nickel in the binary nickel-aluminum alloys), on the concentration of NaCl, and рН of unbuffered NaCl solutions with the additions of HCl or NaOH are determined. The anodic behavior of the alloys in a wide potential range is studied using the potentiodynamic method and the method of stepwise raising anodic potential with an exposure of electrode at each potential for a certain time. The dependences of pitting potential on the concentration of solution are determined for two intermetallic compounds.
Stefano Trasatti and Juliet Ippolito
K. V. Rybalka et al., "Electrochemical Behavior of Nickel-Aluminum Alloys in Sodium Chloride Solutions", Advanced Materials Research, Vol. 138, pp. 7-20, 2010