Understanding the corrosion behavior of isomorphous Cu–Ni alloy from its electron work function

• Increasing %Ni resulted in higher overall electron work function of Cu–Ni alloy.
• Higher EWF corresponded to higher resistance to corrosion in a HCl solution.
• Trend was reversed in a NaCl solution due to the formation of oxide scale.
• During slurry-jet tests, alloys with higher EWFs performed better.

The electrode potential or galvanic series is usually used to reflect the nobility of metals and semi-metals. However, this potential is environment-dependent and the intrinsic nobility of a metal is ultimately governed by its electron stability, which can be represented by the electron work function (EWF). This article reports our studies on the corrosion behavior of isomorphous Cu–Ni alloy in HCl and NaCl solutions, respectively. It was demonstrated that the EWF of the alloy increased as the Ni concentration was increased, so did the corrosion resistance in the acidic solution. In the sodium chloride solution, however, the trend was reversed due to adsorption, hydrolysis and the formation of oxide scale on Cu-rich samples, which more or less prevented them from further corrosion in this solution. In order to confirm this, corrosive wear tests were performed to analyze the performance of the alloy when the effect of oxide scale was eliminated or minimized by the mechanical action.