Hard solids with predominantly covalent–ionic bonding are finding rapidly increasing usage in many modern technologies. However, this class of solids is severely limited by their intrinsic brittleness—they break easily. It is in this context that a fundamental knowledge of brittle fracture mechanisms is of practical importance. This review covers the essential features of crack behavior in characteristically brittle solids, starting with fundamental physical and chemical models, with distinctions between equilibrium and kinetic states, stability and instability, and crack propagation and initiation. Means of imparting higher strength and toughness to otherwise brittle materials are then explored along with their pros and cons. Select technological areas where fracture properties constitute a vital facet of material function—windows and display panels, structural ceramics, biomaterials, layer structures, manufacturing, and nanomechanics—are then presented as illustrative case studies. The balance between factors such as strength and toughness, scaling and threshold effects, and crack containment and crack avoidance, as well as structure at the atomic and microstructural scales, emerge as critical factors in materials design.

中文翻译：

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脆性固体：从物理和化学到材料应用

以共价离子键为主的硬固体在许多现代技术中的使用正在迅速增加。然而，这类固体因其固有的脆性而受到严重限制——它们很容易破裂。正是在这种背景下，脆性断裂机制的基础知识具有实际意义。这篇综述涵盖了脆性固体中裂纹行为的基本特征，从基本的物理和化学模型开始，平衡状态和动力学状态、稳定性和不稳定性以及裂纹扩展和引发之间的区别。然后探索赋予脆性材料更高强度和韧性的方法及其优缺点。然后选择断裂特性构成材料功能重要方面的技术领域（窗户和显示面板、结构陶瓷、生物材料、层结构、制造和纳米力学）作为说明性案例研究。强度和韧性、尺度效应和阈值效应、裂纹遏制和裂纹避免以及原子和微观结构尺度的结构等因素之间的平衡成为材料设计中的关键因素。