The long-period-stacking-ordered (LPSO) structure affects the mechanical, corrosion and hydrolysis properties of Mg alloys. The current work employs high angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) and atom probe tomography (APT) to investigate the structural and local chemical information of LPSO phases formed in Mg-Ni-Y/Sm ternary alloys after extended isothermal annealing. Depending on the alloying elements and their concentrations, Mg-Ni-Y/Sm develops a two-phase LPSO + α-Mg structure in which the LPSO phase contains defects, hybrid LPSO structure, and Mg insertions. HAADF-STEM and APT indicate non-stoichiometric LPSO with incomplete Ni(Y/Sm) clusters. In addition, the APT quantitatively determines the local composition of LPSO and confirms the presence of Ni within the Mg bonding layers. These results provide insight into a better understanding of the structure and hydrolysis properties of LPSO-Mg alloys.

中文翻译：

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Mg-Ni-Y/Sm合金中非化学计量长周期堆垛有序结构的扫描透射电子显微镜和原子探针断层扫描分析

长周期堆垛有序（LPSO）结构影响镁合金的力学、腐蚀和水解性能。目前的工作采用高角度环形暗场扫描透射电子显微镜（HAADF-STEM）和原子探针断层扫描（APT）来研究延伸后Mg-Ni-Y/Sm三元合金中形成的LPSO相的结构和局部化学信息。等温退火。根据合金元素及其浓度，Mg-Ni-Y/Sm 形成两相 LPSO + α-Mg 结构，其中 LPSO 相包含缺陷、混合 LPSO 结构和 Mg 插入。 HAADF-STEM 和 APT 表示具有不完整 Ni(Y/Sm) 团簇的非化学计量 LPSO。此外，APT 定量确定了 LPSO 的局部成分，并确认了 Mg 键合层中存在 Ni。这些结果有助于更好地理解 LPSO-Mg 合金的结构和水解性能。