Kou Zongde, Feng Tao, Lan Si, Tang Song, Yang Lixia, Yang Yanqing, Wilde Gerhard
Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, PR China.
College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, PR China.
Nano Lett. 2022 Aug 10;22(15):6229-6234. doi: 10.1021/acs.nanolett.2c01763. Epub 2022 Jul 25.
Twins are generally regarded as obstacles to dislocations in face-centered cubic metals and can modify individual dislocations by locking them in twin boundaries or obliging them to dissociate. Through in situ tensile experiments on Al thin film in a transmission electron microscope, we report a dynamic process of dislocations being transported by twin lamella via periodic twinning and detwinning at the atomic scale. Following this process, a 60° dislocation first transforms into a sessile step of the twin boundary, then migrates under stress as a step and finally reverts back into a 60° dislocation. Our results reveal a novel evolution route of dislocations by a dislocation-twin interaction where the twins act as transport vehicles rather than as obstacles. The potential implications of this mechanism on toughening are also discussed.
孪晶通常被认为是面心立方金属中位错运动的障碍，并且可以通过将位错锁定在孪晶界或将其迫使解离来改变单个位错。通过在透射电子显微镜中对铝薄膜进行原位拉伸实验，我们报道了位错在原子尺度上通过周期性孪晶和去孪晶被孪晶薄片传输的动态过程。在此过程之后，一个60°位错首先转变为孪晶界的固定台阶，然后在应力作用下作为台阶迁移，最后又变回60°位错。我们的结果揭示了一种通过位错 - 孪晶相互作用的位错新演化途径，其中孪晶充当传输载体而非障碍。还讨论了这种机制对增韧的潜在影响。
