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.