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

Abstract The corrosion properties of as cast Cu 91.6 Nd 8.4 and Cu 90.5 Er 9.5 (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 Cu 6 Nd and Cu 5 Er intermetallic compounds are microstructural features which play a very important role in determining the corrosion behaviour of Cu 91.6 Nd 8.4 and Cu 90.5 Er 9.5 eutectic alloys.