As-cast microstructure Mg-5Zn-2Al-0.3Mn (ZA52) magnesium alloy consists of the α-Mg and eutectic phase Mg51Zn20. The eutectic Mg51Zn20 have been gradually replaced by Al4RE phases when RE is added into the ZA52 alloy, further addition of RE leads to the increasing of grain boundary phases with Mg51Zn20 eutectic compounds reappearing and the grains size refining. Improved elevated temperature properties are obtained as compared to the ZA52 based alloy due to the thermal stability of Al-RE phases. At the temperature up to 175 C, the creep resistance of RE containing alloys decrease with the refining grains size and Mg51Zn20 eutectic compounds increasing.

The hot tensile deformation process of traditional extrusion alloy ZA41 with different temperatures and stain rates is investigated. During the investigation the results show that under the condition of the deformation temperatures ranging from 583 to 613K and strain rates ranging from 5×10 . The experimental peak stress of ZA41 alloy also shows a decline with the rise of temperature and the decrease of strain rate. Microstructure observations suggest that plastic deformation fracture at high temperature and low strain rate occurs after the connection and expansion of the cavities distributing along triangular grain boundary, and grain boundary movement with cavity coordination makes an important contribution to the superior plasticity.