中文摘要：

当演员组 AZ91 Mg 合金样品是低温实验法的与不同时间对待。否则，光显微镜(OM ) ，机械测试，抵抗测试和 XRD 分析被用来在低温实验法的处理(CT ) 前后研究微观结构进化和样品的物理变化。由于 CT，当演员组 AZ91 Mg 合金的结构从混乱稳固的答案被改变到订的稳固的答案。第一，订的稳固的答案的外观在 CT 以后导致山峰应力的改进，因为加强订。第二，抵抗和样品的结晶的格子常数显然减少。否则，在低温实验法的环境从矩阵被创造的框架类型 twinning 能妨碍成双的生长并且引起订的加强。

英文摘要：

The as-cast AZ91 Mg alloy samples were cryogenic treated with different time. Otherwise, optical microscope （OM）, mechanical test, resistance test and XRD analysis were used to research the microstructure evolution and physical variation of the samples before and after cryogenic treatment （CT）. Due to CT, the structure of as-cast AZ91 Mg alloy was changed from disordered solid solution to ordered solid solution. Firstly, the appearance of ordered solid solution leads to the improvement of peak stress after CT, because of ordered strengthening. Secondly, resistance and crystallographic lattice constant of the samples reduce obviously. Otherwise, the frame-type twinning which is created from matrix in the cryogenic environment could hinder the twin growth and cause the ordered strengthening.