Structural characterization by high-resolution electron microscopy of an Al–Mg alloy processed by high-pressure torsion
Structural characterization by high-resolution electron microscopy of an Al–Mg alloy processed by high-pressure torsion
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DOI：
10.1016/j.msea.2008.02.053
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发表时间：
2009-03
期刊：
影响因子：
6.4
通讯作者：
Manping Liu;H. Roven;M. Murashkin;R. Valiev
中科院分区：
文献类型：
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作者：
Manping Liu;H. Roven;M. Murashkin;R. Valiev
利用高分辨透射电子显微镜（TEM）研究了纳米Al-Mg合金高压扭转过程中的缺陷和变形结构，包括0°和60°全位错、30° Shockley偏位错、层错和形变孪晶。先前通过分子动力学模拟预测的孪生机制，即，直接验证了涉及晶粒内部堆垛层错动态重叠的均匀机制。实验上观察到由四个层错动态叠加形成的四层孪晶。实验证实了部分位错在超细晶中形成的形变孪晶和层错。这些结果表明，部分位错发射晶界可能成为一种变形机制，在超细晶铝在剧烈的塑性变形。
Defects and deformation structures including 0° and 60° full dislocations, 30° Shockley partials, stacking faults and deformation twins in a nanostructured Al–Mg alloy processed by high-pressure torsion were identified using high-resolution transmission electron microscopy. The twinning mechanism previously predicted by the molecular dynamics simulation, i.e., the homogeneous mechanism involving dynamic overlapping of the stacking faults inside grains, was directly verified. A four-layer twin formed by the dynamic overlapping of four stacking faults was experimentally observed. Deformation twins and stacking faults formed by partial dislocations in ultrafine grains were experimentally confirmed. These results suggest that partial dislocation emissions from grain boundaries could become a deformation mechanism in ultrafine-grained aluminum during severe plastic deformation.