The anisotropy electrochemical corrosion behavior of Ni-based single crystal superalloy on different crystal planes: An investigation from the film growth aspect

Abstract

The electrochemical corrosion and passivation behaviors of DD5 Ni-based single crystal superalloy with different crystal orientations were compared. The corrosion resistance and film growth behaviors of three different oriented samples were evaluated by using electrochemical techniques. The compositions of passive film and the corrosion morphologies on various crystal planes were revealed by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The electrochemical processes on the sample surfaces were further analyzed based on the surface energy and the point defect model (PDM). The results revealed that the dissolution rates of the three tested planes lie in the order of (011) < (001) < (111), and the passive film grows faster and denser on the plane with higher surface energy. The presence of Cr2O3 and the enrichment of MoO3 in the passive film can enhance the corrosion resistance of (011) plane. Our results can provide an in-depth understanding of the correlations between the surface energies, the film growth behaviors, and the electrochemical corrosion behaviors of planes with different crystal orientations.