Effects of Nd on the microstructure of ZA52 alloy

Microstructure changes brought by the addition of Nd element to the Mg-5 wt.% Zn-2 wt.% Al alloy are investigated, results show Al element takes a priority to react with Nd element over Mg and Zn, forming binary phases Al2Nd or Al11Nd3, the relative ratio of two Al-Nd phases in the microstructure is found to relate to the weight percentage of Nd element. With a larger Nd addition, the dominant phase is bacillary Al11Nd3 phase. Divorced eutectic phase in the microstructure is verified to be Mg51Zn20, the morphology and the distribution of Mg-Zn phase are also affected by the Nd addition. The solution behaviors of Mg-5 wt.% Zn-2 wt.% Al and Mg-5 wt.% Zn-2 wt.% Al-4 wt.% Nd alloys are also studied, XRD result shows Al11Nd3 phase decomposes during the longer hour solution at 345 °C, but no γ phase (Mg17Al12) is detected.