Effect of Mg-Zn-Nd Quasicrystal Addition on Corrosion Resistance of AZ91 Alloys

The purpose of this study is to improve the corrosion resistance of AZ91 alloys through adding different contents of Mg-Zn-Nd quasicrystal master alloy. The microstructure and the corrosion behavior of AZ91 alloys with addition of Mg-Zn-Nd (MZN) quasicrystal master alloy were investigated by scanning electron microscopy (SEM) equipped with electron dispersive spectroscopy (EDS), X-ray diffractometry (XRD), mass loss tests and potentiodynamic polarization measurements. The results show that the microstructures of AZ91 alloys are significantly refined, and the morphology of β-Mg17Al12 phase changes from a continuous net to a discrete net or even to particles after adding MZN quasicrystal master alloy. Moreover, the amount of β-Mg17Al12 phase is reduced. The alloy with 6wt% MZN quasicrystal master alloy has the best corrosion resistance, and the corrosion rate is 0.8 (mg·cm−2)/d, only 1/15 of that of common AZ91 alloy, but the excessive MZN quasicrystal master alloy could result in a poorer corrosion resistance of AZ91 alloy.