First-principles calculation and experimental study on the effect of rare earth Ce and Nd on the corrosion behavior of Mg alloys

Abstract

Mg-0.3%Ce, Mg-0.3%Nd binary rare earth magnesium alloys were formed by adding 0.3ωt% Ce and Nd to pure magnesium, respectively. The second phase of the alloy was observed and analyzed using scanning electron microscopy (SEM) and energy spectrometry (EDS). Transmission electron microscopy (TEM) at high magnification was used to analyze the histomorphology, crystal structure, and dislocation relationships of the specimens in micro-regions. The relative potential difference between the rare earth phase and the matrix in the alloy was tested using the SKPFM module of the Scanning Probe Microscope (SPM). Electrochemical tests were carried out on the polarization curves and electrochemical impedance spectra of the rare-earth magnesium alloys using a German Zennium electrochemical workstation. The surface energy, work function, and binding energy of the two binary alloys were calculated using the first nature principle. The results show that the addition of the light rare-earth elements Ce and Nd increases the surface energy of the magnesium alloys and decreases the electron work function of the magnesium (0001) base surface and the binding energy of the second phase and the magnesium matrix, resulting in an unstable surface and easier corrosion.