Abstract Vacancies play an essential role on mechanical properties of ceramics, while it is a challenge to reveal the atomistic process of vacancy-driven failure mechanism due to difficulty in characterizing the atomic defects. Here, we used hexagonal silicon nitride as a prototype ceramic and report the shear localization as a main failure mechanism, which is characterized by combining nanoindentation and scanning transmission electron microscopy. It is revealed that the intrinsic point defects in silicon nitride triggers the nanoscale shear bands on the prismatic slip plane when subjected to high stresses. The quantum mechanics simulations ascertained that the shear bands are mediated by nitrogen defects in tetragon sites during the pure shear deformation.

中文翻译：

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氮化硅中空位驱动的剪切定位

摘要 空位对陶瓷的机械性能起着至关重要的作用，而由于难以表征原子缺陷，揭示空位驱动失效机制的原子过程是一个挑战。在这里，我们使用六方氮化硅作为陶瓷原型，并将剪切局部化作为主要失效机制，其特征是结合纳米压痕和扫描透射电子显微镜。结果表明，当受到高应力时，氮化硅中的本征点缺陷会触发棱柱滑移面上的纳米级剪切带。量子力学模拟确定剪切带是由纯剪切变形过程中四边形位点中的氮缺陷介导的。