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Effect of Zn on the microstructure, age hardening response and mechanical properties of Mg3Sn-1Al alloy which is immediately aged at 180uC after extrusion process (T5) was investigated. It was found that the Zn can refine the microstructure, remarkably improve the aging response with the peak hardness increases to 75 HV and the time to peak hardness reduces from y110 to y60 h, which is attributed to the solid solution hardening of Al, Zn and an amount of finer Mg 2 Sn precipitates. The as aged Mg-3Sn-2Zn-1Al alloy exhibits better mechanical property at room temperature or 150uC than that of Mg-3Sn-1Al alloy, which is ascribed to the fine grained microstructure and thermally stable Mg 2 Sn particles dispersed at grain boundaries and in the matrix.

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Effects of Nd additions (0–4 wt-) on microstructures and properties of Mg–Al–Ca alloy at room temperature and 150°C have been investigated. The results showed that Mg–6Al–2Ca alloy consisted of α-Mg matrix, Mg17Al12, Mg–Ca and Al–Ca phases. The amount of Al–Nd phase increases with the increasing of Nd content while that of Mg17Al12 decreases. On the other hand, Nd refines the microstructure of as cast and extruded alloys. The ultimate strength and yield strength of experimental alloys are improved with the addition of Nd, and the largest values are 319 and 210 MPa respectively at room temperature. When the temperature was elevated to 150°C, with the increasing of Nd, ultimate strength and yield strength of experimental alloys are first increased and subsequently decreased. Mg–6Al–2Ca– xNd alloy has the best ultimate strength and yield strength at 150°C, which reaches 265 and 179 MPa respectively when the content of Nd reached 3.