Revealing deformation mechanisms in Mg–Y alloy by in situ deformation of nano-pillars with mediated lateral stiffness
Revealing deformation mechanisms in Mg–Y alloy by in situ deformation of nano-pillars with mediated lateral stiffness
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DOI：
10.1557/jmr.2019.124
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发表时间：
2019-05
影响因子：
2.7
通讯作者：
Dalong Zhang;Lin Jiang;Xin Wang;I. Beyerlein;A. Minor;J. Schoenung;S. Mahajan;E. Lavernia
中科院分区：
文献类型：
--
作者：
Dalong Zhang;Lin Jiang;Xin Wang;I. Beyerlein;A. Minor;J. Schoenung;S. Mahajan;E. Lavernia
在我们之前的研究中，我们观察到变形的Mg-Y合金中缺少$\left\{ {10\bar 12} \right\}$ { 10 1 <$2}孪晶，这有助于观察到的屈服“对称性”。然而，织构和晶粒尺寸对多晶变形的影响使得很难完全理解为什么孪晶不活跃。因此，我们在此报告通过原位透射电子显微镜进行的深入研究，即，原位TEM原位变形的纳米尺寸的Mg-Y柱显示，棱柱滑移优于孪生，即，激活棱柱滑移所需的临界应力低于孪生。这一发现与其他纳米/微米柱变形研究中报道的完全不同，其中孪生总是占主导地位的变形机制。通过测量的临界应力为基础，棱柱形，金字塔形的滑移系统，这在原位TEM研究也揭示了合金元素Y的影响，降低内在的塑性各向异性的Mg基体。
In our previous study, we observed a lack of $\left\{ {10\bar 12} \right\}$ { 10 1 ¯ 2 } twinning in a deformed Mg–Y alloy, which contributed to the observed yield “symmetry.” However, the effects of texture and grain size on polycrystalline deformation made it difficult to fully understand why twinning was not active. Therefore, we report herein in-depth study by in situ transmission electron microscopy, i.e., in situ TEM. The in situ deformation of nano-sized Mg–Y pillars revealed that prismatic slip was favored over twinning, namely, the critical stress required to activate prismatic slip was lower than that for twinning. This finding diametrically differs from that reported in other nano/micro-pillar deformation studies, where twinning is always the dominant deformation mechanism. By measuring the critical stresses for basal, prismatic, and pyramidal slip systems, this in situ TEM study also sheds light on the effects of the alloying element Y on reducing the intrinsic plastic anisotropy in the Mg matrix.