Abstract

In order to study the deformation and fracture mechanism of machinable mica glass ceramics under different loading modes, quasi-static uniaxial tensile and compression experiments are designed and analyzed based on the obtained quasi-static stress-strain curves at different strain rates, the macroscopic and microscopic fracture morphology of the samples and the nano-indentation experiment. The results show that mica glass ceramics are basically elastic brittle bodies. A very short “softening” section before the compression fracture is observed. There is a significant SD (tensile and compressive strength difference) effect, and the ratio of compressive to tensile strength is 14. The fracture mechanism of mica glass ceramics is related to the loading mode. The fracture mechanism is normal tensile fracture perpendicular to the loading axis under tensile loading. Under compressive loading, there is a mixed mode of distensile splitting and local shear failure. The microcrack is preferentially nucleated and extends to the weak interface at the junction of two phases, and the critical nucleation load is about 20 mN. The energy consumption mechanism of crack initiation and propagation at the weak interface and cleavage steps are the reason for the softening of the compression end curve.

中文翻译：

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准静态条件下可加工云母玻璃陶瓷的断裂机理研究

摘要

为了研究可加工云母玻璃陶瓷在不同加载方式下的变形和断裂机理，基于所获得的在不同应变速率下的准静态应力-应变曲线，设计并分析了准静态单轴拉伸和压缩实验。样品的微观断裂形态和纳米压痕实验。结果表明，云母玻璃陶瓷基本上是弹性的脆性体。在压缩断裂之前观察到非常短的“软化”部分。具有显着的SD（拉伸强度和压缩强度差）效果，压缩强度与拉伸强度之比为14。云母玻璃陶瓷的断裂机理与加载方式有关。断裂机理是在拉伸载荷作用下垂直于载荷轴的法向拉伸断裂。在压缩载荷下，存在扩张分裂和局部剪切破坏的混合模式。微裂纹优先成核并延伸至两相交界处的弱界面，临界成核载荷约为20 mN。裂纹在薄弱界面处萌生和扩展以及开裂步骤的能量消耗机制是压缩端曲线变软的原因。