Effect of La/Nd Ratio on the Microstructure and Corrosion Behaviors of Squeeze-Cast Mg-Al-Zn-La-Nd Alloys

The current study investigated the effect of adding La and Nd on the microstructural evolution and corrosion response of AZ91 magnesium alloy. Mg-Al-Zn-La-Nd alloys with different W-La/W-Nd ratios were developed by the squeeze casting process. Typical characterization was conducted using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning Kelvin probe force microscopy (SKPFM), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) tests to analyze the effect of W-La/W-Nd on the corrosion performance of Mg-Al-Zn-La-Nd alloys. AZLN alloys showed better corrosion resistance, mainly due to the microstructure refinement of RE addition and the protective effect of RE oxide films. In addition, the acicular Al11RE3 phase acts as a barrier against corrosion and is more effective than the granular Al2RE phase. As a result, the Mg-Al-Zn-La-Nd alloy with a W-La/W-Nd ratio of 3/2 is more corrosion resistant than other alloys due to its finer morphology and more uniform distribution of secondary phases.

Automated summary

The effect of adding La and Nd on the microstructural evolution and corrosion response of AZ91 magnesium alloy was investigated in this study. The results showed that the addition of La and Nd improved the corrosion resistance by refining the microstructure and forming protective oxide films. Furthermore, the acicular Al11RE3 phase was found to be more effective than the granular Al2RE phase in hindering corrosion.