ELECTROCHEMICAL CORROSION BEHAVIOR OF DIFFERENT GRAIN SIZED Cu-50Cr ALLOY IN ACIDIC MEDIA

Cu-50Cr alloys with the different grain size were prepared by conventional casting and hot-pressing the mechanically pre-alloyed powder.Then their corrosion behavior in acidic media was investigated by mesearements of potentiodynamic polarization curves and electrochemical impedance spectroscopy(EIS).With the increment of hydrogen ion concentrations of the media,their corrosion current densities increased and therefore corrosion rates became faster.The corrosion current densities of nanocrystalline Cu-50Cr alloy were higher than those of the corresponding coarse grained material.This showed that the corrosion resistance decreased when the grain size was refined.The corrosion processes of the coarse grained Cu-50Cr alloy are controlled by the electrochemical reactions,while those of the nanocrystalline Cu-50Cr alloy are controlled by the electrochemical reactions initially and afterwards diffusion.