A novel orientation relationship (OR) between the ε′ precipitates and Mg matrix has been characterized in a Mg-Sn-Ag-Zn-Mn alloy. This OR is expressed by (0 2 0)_ε′//(0 0 0 2)_α, [0 0 2]_ε′//[1 1 \( \bar{2} \) 0]_α. The ε′ precipitates exhibit two major pairs of facets parallel to (1 0 \( \bar{1} \))_ε′ and (1 0 1)_ε′ and a minor pair of facets of (0 0 2)_ε′. The reason for the appearance of these interface orientations has been consistently explained by the secondary constrained coincidence site lattice (II-CCSL) model. In other words, the observed facets are preferred because of their smaller interface misfit. The interfacial structures of the three facets were determined to be microscopically flat by the model. These crystallographic features are similar but definitely different from the previously reported ε′ precipitates with an OR of (0 0 2)_ε′//(0 0 0 2)_α, [2 0 0]_ε′//[1 1 \( \bar{2} \) 0]_α. A comprehensive evaluation of the interface misfit and the lattice strain to sustain the II-CCSL structure showed that neither type of precipitate is clearly superior to the other. Moreover, a growth-ledge-aided morphology evolution path of the precipitates was proposed according to the experimental results, indicating that both thermodynamic and kinetic factors should be considered in understanding the precipitate morphology.

在Mg-Sn-Ag-Zn-Mn合金中，表征了ε '析出物与Mg基体之间的新型取向关系（OR）。该OR表示为（0 2 0）_{ε '} //（0 0 0 2）_α， [0 0 2] _{ε '} // [1 1 \（\ bar {2} \） 0] _α。该ε '析出物表现出小面的两个主要对平行于（1 0 \（\巴{1} \） ）_{ε '}和（1 0 1）_{ε '}和次要对（0 0 2）的小平面的_{ε '}。这些界面方向出现的原因已由次要约束重合位点晶格（II-CCSL）模型一致地解释。换句话说，观察到的小平面是首选，因为它们的界面失配较小。该模型确定了三个小面的界面结构在显微镜下是平坦的。这些晶体学特征与先前报道的ε '析出物相似，但绝对不同，其OR为（0 0 2）_{ε '} //（0 0 0 2）_α， [2 0 0] _{ε '} // [1 1 \（ \ bar {2} \） 0] _α。对界面失配和维持II-CCSL结构的晶格应变的综合评估表明，两种沉淀物都不明显优于另一种。此外，根据实验结果，提出了析出物的生长边缘辅助形态演化路径，表明在理解析出物形态时应同时考虑热力学和动力学因素。