中文摘要：

本文利用原位准动态背散射电子显微像（BSE）并结合透射电镜观察研究了MgGd1.8Y0.8Znx（at.%）（x=0.12,0.8,1.3）合金中长周期堆垛结构（LPS）的形成及生长形态。结果表明,当Zn含量较少时（x=0.12）,铸态和各种热处理状态的合金中都未形成LPS。而在Zn含量相对较多的铸态合金（x=0.8,1.3）中,发现6层周期LPS的形成,而且Zn含量越多,LPS的体积分数越大。在300℃进行热处理时,LPS可以沿Mg基体{0001}面生长,原位准动态BSE观察可以直接揭示与LPS的生长相关的形貌变化。

英文摘要：

The formation and growth morphology of long period stacking （LPS） structures in MgGd1.8 Y0.8 Znx （at. % ） （x = 0.12, 0. 8, 1.3） alloys have been investigated by combination of in-situ quasi-dynamic back-scattering electron microscopy （BSE） and transmission electron microscopy. The results show that no LPS can be formed in as-cast and heat treated MgGd1.8 Y0.8 Znx alloys when Zn-content is low （ x = 0. 12）. In contrast, a kind of 6-layered LPS has been found to form in as-cast MgGd1.8 Y0.8 Znx alloys with high Zn-content （x = 0.8, 1.3）. The fraction of volume for the LPS formed is in proportion to Zn-content. When heat treated at 300℃, the LPS in as-cast state can grow along （0001） Mg planes, whose morphology variations can be revealed directly by in-situ quasi-dynamic BSE observations.