Abstract: | The effects of RE on the microstrcture of as-cast Mg-8Zn-4Al magnesium alloys were investigated. The results show that the solidification range of Mg-8Zn-4Al-xRE alloys increases with RE additions. A binary eutectic reaction can arise and produce a new phase (Mg3Al4Zn2RE) and the temperature of phase transformation point of the new phase is 412.85C. In Mg-8Zn-4Al-1.5RE alloy, a small amount of Mg3Al4Zn2RE phase and ε phases are found besides α(Mg),ψ and τ phases. Also microstructures of Mg-8Zn-4Al alloys can be refined by addition of 1.5 % RE obviously. |