New insights on the different corrosion mechanisms of Mg alloys with solute-enriched stacking faults or long period stacking ordered phase

Formation of profuse I2-type solute-enriched stacking faults (SESFs) in fine grains and transformation of SESFs to 18R-long period stacking ordered (LPSO) phase are attained in Mg-Er-Zn-Zr alloys. It is first confirmed by scanning Kelvin probe force microscopy (SKPFM) that SESFs with nanostructure act as weak anodes and the 18R-LPSO phase serves as cathode, which are verified by the theoretical calculated electronic work function and observation of scanning transmission electron microscope. Furthermore, the preferential corrosion of uniformly dispersed SESFs is demonstrated to be conducive to forming effective passivation film. It provides a new insight for developing high-strength and anti-corrosion Mg alloys.