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通过透射电子显微镜对铸态Mg-3Cu-1Mn-2Zn-1Y阻尼合金进行表征,观察到14H、18R和24R三种类型的长周期结构。这些长周期结构含有Mg、Y、Zn和Cu的四元相。获得了24R结构的明锐衍射斑点,并测得衍射斑中g1100与g10024R的夹角为5.03°。高分辨晶格条纹显示,24R结构中经常包含两种类型的特征条纹间距。基于实验结果提出,将6H、7H和8H分别作为18R、14H和24R长周期结构的结构单元。24R结构的单胞可以认为是由三个8H单元沿相同的方向切变5.03°堆垛而成的,具有缺陷的24R结构主要是由8H单元和少量的6H单元通过有序或者无序的方式堆垛而成的。这种双单元结构模型也可以解释之前观察到的长周期结构中的缺陷。
The as-cast Mg-3Cu-1Mn-2Zn-1Y damping alloys were characterized by transmission electron microscopy and three types of long-period structures, 14H, 18R and 24R, were observed. These long-period structures contain quaternary phases of Mg, Y, Zn and Cu. The sharp diffraction spot of 24R structure was obtained and the angle between g1100 and g10024R in the diffraction spot was measured as 5.03 °. High-resolution lattice fringes show that the 24R structure often contains two types of feature fringe spacings. Based on the experimental results, it is proposed that 6H, 7H and 8H be the structural units of long period structures of 18R, 14H and 24R, respectively. The unit cell of 24R structure can be considered as a stack of three 8H units cut in the same direction at 5.03 °. The defective 24R structure is mainly composed of 8H units and a small amount of 6H units in an ordered or disorder manner Stacked. This dual cell structure model can also explain previously observed defects in long-period structures.