Effect of Nd Addition on the Microstructure, Mechanical and Corrosion Properties of Mg-Zn-Y-Nd Alloys

Abstract

The microstructure of as-cast Mg97-xY2Zn1Ndx (x = 0, 0.5, 1.0 and 2.0 at. %) alloys was investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mechanical properties were measured by universal testing machine. The corrosion behavior was evaluated by Tafel curves and hydrogen evolution reaction. The results showed that the α-Mg, MgZn, Mg12Nd and Mg12YZn phases exist in the Mg-Zn-Y-Nd alloy. Mg12YZn is a long period stacked ordered (LPSO) phase. When x is, the addition of less than 1at. % Nd can promote the formation of LPSO phase. The addition of more than 1at. %Nd could result in the formation of Mg12Nd phase, and the volume fraction of the Mg12Nd phase in Mg95Zn1Y2Nd2 alloy is larger than that of others. The ultimate tensile strength (UTS) of Mg96ZnY2Nd1 alloy reaches 197.8MPa because of small grain size and uniform distribution of the LPSO and MgZn phases. The corrosion rate of Mg96.5Zn1Y2Nd0.5 alloy is lower than that of other alloys due to its lower self-corrosion current density and hydrogen evolution rate.