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

摘要

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 nat urally aerated 1 M NaOH solution, pH = 14, at room temperature, by means of potentiodynamic polariza tion 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_6Nd and Cu_5Er intermetallic compounds are microstructural features which play a very important role in deter mining the corrosion behaviour of Cu_(91.6)Nd_(8.4) and Cu_(90.5)Er_(9.5) eutectic alloys.