Bending deformation and self-restoration of submicron-sized graphite cantilevers
Bending deformation and self-restoration of submicron-sized graphite cantilevers
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DOI：
10.1016/j.actamat.2022.118381
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发表时间：
2022-09
期刊：
影响因子：
9.4
通讯作者：
M. Akiyoshi;Shunya Koike;T. Shimada;H. Hirakata
中科院分区：
文献类型：
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作者：
M. Akiyoshi;Shunya Koike;T. Shimada;H. Hirakata
范德华 (vdW) 堆叠材料由于其强的面内原子键和弱的层间 vdW 相互作用而表现出独特的机械性能。在这项研究中，我们通过实验证明亚微米尺寸的石墨悬臂可以适应大的面外变形而不破裂，并且在卸载时可以自我恢复。亚微米尺寸的悬臂梁样品是使用聚焦离子束方法由高度取向的热解石墨制成的，并进行了基于原位透射电子显微镜的弯曲测试。悬臂表现出非线性的载荷-位移关系，尽管在加载-卸载过程中观察到较大的磁滞回线，但其变形在卸载时几乎完全恢复。此外，在同一试件的重复加载过程中获得了相似的加载-卸载曲线，表明即使在较大的非线性变形的情况下，通过卸载也可以恢复力学性能。对于较大的变形，会发生塑性变形，失去自恢复性能。然而，即使悬臂变形至62°的偏转角，也没有观察到明显的断裂。即使在这种情况下，也可以通过电子束照射来恢复变形。基于所获得的结果，我们提出了一种解释样本的非线性和完全可逆变形行为的机制。
Van der Waals (vdW)-stacked materials exhibit unique mechanical properties owing to their strong in-plane atomic bonds and weak interlayer vdW interactions. In this study, we experimentally demonstrate that submicron-sized graphite cantilevers can accommodate large out-of-plane deformations without fracturing and undergo self-restoration upon unloading. Submicron-sized cantilever beam specimens were fabricated from highly oriented pyrolytic graphite using the focused ion beam method and subjected toin situtransmission electron microscopy-based bending tests. The cantilevers exhibited a nonlinear load–displacement relationship, and their deformation was almost completely restored upon unloading, even though a large hysteresis loop was observed during the loading–unloading process. Moreover, similar loading–unloading curves were obtained during the repeated loading of the same specimen, indicating that the mechanical properties were restored by unloading even in the case of large nonlinear deformations. For larger deformations, plastic deformation occurred, and the self-restoration property was lost. However, no clear fracture was observed in the cantilevers even when they were deformed to a deflection angle of 62°. Even in this case, the deformation could be restored by electron-beam irradiation. Based on the obtained results, we propose a mechanism to explain the nonlinear and fully reversible deformation behavior of the specimens.