Ohmura Takahito, Wakeda Masato
Research Center for Structural Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047, Japan.
Materials (Basel). 2021 Apr 9;14(8):1879. doi: 10.3390/ma14081879.
The attractive strain burst phenomenon, so-called "pop-in", during indentation-induced deformation at a very small scale is discussed as a fundamental deformation behavior in various materials. The nanoindentation technique can probe a mechanical response to a very low applied load, and the behavior can be mechanically and physically analyzed. The pop-in phenomenon can be understood as incipient plasticity under an indentation load, and dislocation nucleation at a small volume is a major mechanism for the event. Experimental and computational studies of the pop-in phenomenon are reviewed in terms of pioneering discovery, experimental clarification, physical modeling in the thermally activated process, crystal plasticity, effects of pre-existing lattice defects including dislocations, in-solution alloying elements, and grain boundaries, as well as atomistic modeling in computational simulation. The related non-dislocation behaviors are also discussed in a shear transformation zone in bulk metallic glass materials and phase transformation in semiconductors and metals. A future perspective from both engineering and scientific views is finally provided for further interpretation of the mechanical behaviors of materials.
在非常小的尺度下，压痕诱导变形过程中出现的引人注目的应变突发现象，即所谓的“弹出”，被作为各种材料中的一种基本变形行为进行讨论。纳米压痕技术可以探测到对非常低的外加负载的机械响应，并且可以对该行为进行力学和物理分析。“弹出”现象可以理解为压痕负载下的初始塑性，小体积内的位错形核是该事件的主要机制。从开创性发现、实验澄清、热激活过程中的物理建模、晶体塑性、包括位错在内的预先存在的晶格缺陷、固溶合金元素和晶界的影响以及计算模拟中的原子建模等方面，对“弹出”现象的实验和计算研究进行了综述。还讨论了块状金属玻璃材料剪切转变区中的相关非位错行为以及半导体和金属中的相变。最后从工程和科学的角度提供了一个未来展望，以进一步解释材料的力学行为。
