Abstract We report atomic-scale observations on the interaction of {101ˉ2} deformation twins with 14H long-period stacking ordered (LPSO) phase in a magnesium alloy. It was found that the interaction strongly depends on the thicknesses of LPSO plates as well as the thickness ratios between LPSO plates and twins. We observed three size-dependent structure responses of LPSO to incoming twins: (1) pure shearing of thin LPSO plates in line with the incursive {101ˉ2} twins; (2) twin-to-dislocation ‘switch’ from the alpha-Mg matrix to LPSO when LPSO/twin thickness ratios are below a critical value of 0.17 ± 0.01; and (3) elastic deformation of LPSO to accommodate the propagation of incoming twin when LPSO/twin thickness ratios are larger than 0.17 ± 0.01. Moreover, the inter-plate spacing of LPSO also influences the propagation modes of twins by controlling nucleation sites of new twins. These size-dependent interactions are accomplished by local structural transition of face-centered cubic units of LPSO during thin plate shearing and formation of gliding dislocations during LPSO deformation and twin blocked. The atomic-scale observations provide fundamental insights into these interaction modes and, hence, the precipitation strengthening mechanisms in Mg alloys under both quasi-static and dynamic loadings.

中文翻译：

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冲击载荷作用下镁合金中变形孪晶与长周期堆积有序析出物的相互作用

摘要 我们报告了镁合金中 {101ˉ2} 变形孪晶与 14H 长周期堆积有序 (LPSO) 相相互作用的原子尺度观察。发现相互作用强烈依赖于 LPSO 板的厚度以及 LPSO 板和孪晶之间的厚度比。我们观察到 LPSO 对进入孪晶的三种尺寸相关的结构响应：（1）LPSO 薄板的纯剪切与侵入 {101ˉ2} 孪晶一致；(2) 当 LPSO/孪晶厚度比低于 0.17 ± 0.01 的临界值时，孪晶到位错“转换”从 α-Mg 基质到 LPSO；(3) 当LPSO/孪晶厚度比大于0.17 ± 0.01 时，LPSO 的弹性变形以适应传入孪晶的传播。而且，LPSO 的板间距也通过控制新孪晶的成核位点来影响孪晶的传播模式。这些与尺寸相关的相互作用是通过 LPSO 的面心立方单元在薄板剪切过程中的局部结构转变以及在 LPSO 变形和孪晶阻塞过程中形成滑移位错来实现的。原子尺度观察提供了对这些相互作用模式的基本见解，因此，镁合金在准静态和动态载荷下的析出强化机制。