高周疲劳变形中二次孪晶与锥面位错之间的关系（英文）

Relationship Between Secondary Twins and Pyramidal Dislocations in a Mg-3Al-1Zn Alloy During High Cycle Fatigue Deformation

采用金相显微镜(OM),扫描电镜(SEM),透射菊池衍射(TKD)和透射电子显微镜(TEM)表征技术,研究了高周疲劳变形后的Mg-3Al-1Zn镁合金的典型断口组织特征,二次孪晶内部的横切面区域被提取出来进行TEM和TKD观察。结果显示断口边缘附近的区域有大量的{1012}{1012}二次孪晶,双束明场技术(TBBF)应用于研究二次孪晶边界的位错类型。研究发现锥面位错在{1012}-{1012}二次孪晶内部被大量的激活,这被认为锥面位错与二次孪晶有关联。二次孪晶内部的局部应力集中将导致锥面位错的形成。

Typical fracture morphology of Mg-3Al-1Zn alloy after cyclic deformation was investigated using optical microscope (OM),scanning electron microscopy (SEM),transmission Kikuchi diffraction (TKD) and transmission electron microscopy (TEM).Cross-section samples were extracted from secondary twin regions for TEM/TKD observation.The results show that a large amount of {1012}-{1012} secondary twins are observed in the region near the fractured edge.Two-beam bright field (TBBF) technique was applied to study the types of dislocations along secondary twin boundaries.It is found that pyramidal dislocations are highly active within {1012}-{1012} secondary twins,which is considered to be related to {1012}-{1012} secondary twins.Localized stress concentration within the secondary twins may lead to the formation of pyramidal dislocations.