Influence of rare earth metals addition on the corrosion behaviour of copper in alkaline environment

The corrosion properties of as cast Cu91.6Nd8.4 and Cu90.5Er9.5 (at.%) eutectic alloys is investigated in naturally aerated 1 M NaOH solution, pH = 14, at room temperature, by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The results are compared with those obtained on pure Cu in order to assess the influence of rare earth (RE) elements on its corrosion behaviour. Microstructural characterization of the alloys investigated was carried out using scanning electron microscopy (SEM) coupled with electron probe microanalysis (EPMA). The electrochemical tests reveal that Cu–RE (RE = Nd, Er) alloys significantly improve resistance to corrosion compared with pure Cu, in spite of their two-phase microstructure. Spatial distribution and volume fraction of Cu6Nd and Cu5Er intermetallic compounds are microstructural features which play a very important role in determining the corrosion behaviour of Cu91.6Nd8.4 and Cu90.5Er9.5 eutectic alloys.

► The corrosion properties of as cast Cu91.6Nd8.4 and Cu90.5Er9.5 (at.%) eutectic alloys have been investigated.
► Electrochemical results are compared with those obtained on pure copper.
► Rare earth metals (Nd, Er) significantly improve the corrosion resistance of pure copper.