Twinning dislocations on {1¯011} and {1¯013} planes in hexagonal close-packed crystals
Twinning dislocations on {1¯011} and {1¯013} planes in hexagonal close-packed crystals
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DOI：
10.1016/j.actamat.2011.03.024
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发表时间：
2011-06
期刊：
影响因子：
9.4
通讯作者：
Jian Wang;I. Beyerlein;J. Hirth;C. Tomé
中科院分区：
文献类型：
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作者：
Jian Wang;I. Beyerlein;J. Hirth;C. Tomé
本研究的目的是通过充分表征Mg晶体的结构来识别{l_brace}1-bar 011{r_brace}和{l_brace}1-bar 013{r_brace}孪晶的元孪晶位错（TD）。对于{l_brace}1-bar 011{r_brace}和{l_brace}1-bar 013{r_brace}孪晶，我们得出结论，2层TD，而不是4层TD，是孪晶中的活跃TD。4层TD可视为两个2层TD与相反符号螺钉组件的组合。Peierls能量的分子静力学模拟显示了为什么两种孪生模式的TD（对于c/a比> 1.5）仅在c轴经历压缩应变时被激活。模拟结果表明，两层位错比四层位错具有更强的移动的能力，并且这些孪晶位错的移动能力强烈地依赖于位错的性质。相应地，变形孪晶过程中涉及的TD对变形孪晶的影响进行了讨论。
The objective of this investigation was to identify the elementary twinning dislocations (TDs) for {l_brace}1-bar 011{r_brace} and {l_brace}1-bar 013{r_brace} twins by fully characterizing their structure for an Mg crystal. For both {l_brace}1-bar 011{r_brace} and {l_brace}1-bar 013{r_brace} twins, we conclude that the 2-layer TD, not the 4-layer TD, is the active TD in twinning. The 4-layer TD can be considered as the combination of two 2-layer TDs with opposite-sign screw components. Molecular statics simulations of the Peierls energy show why the TDs of both twinning modes (for c/a ratios > 1.5) are only activated when the c-axis experiences a compressive strain. The simulations predict that 2-layer TDs are more mobile than 4-layer TDs and that the mobility of these twinning dislocations depends strongly on dislocation character. Correspondingly, the influence of TDs involved in deformation twinning processes on deformation twins is discussed.