Fracture and deformation in brittle solids: A perspective on the issue of scale
Fracture and deformation in brittle solids: A perspective on the issue of scale
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DOI：
10.1557/jmr.2004.19.1.22
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发表时间：
2004-01
影响因子：
2.7
通讯作者：
B. Lawn
中科院分区：
文献类型：
--
作者：
B. Lawn
提出了一个关于通常脆性共价离子固体（陶瓷）断裂和变形特性中尺度问题的观点。这类固体的nanomechanical性能的特征缩放尺寸被识别的试样尺寸或层厚度，微观结构的规模，和接触尺寸。当特征尺寸从宏观尺度减小到亚微观尺度时，机械损伤过程发生转变。这种过渡一般排除无条件外推宏观尺度的断裂和变形规律到纳米力学区域。随着尺度的减小，脆性固体的强度趋于增加，而韧性趋于降低。在亚微米尺度区域控制强度的缺陷的性质也发生了根本性的变化，即使没有发育良好的微裂纹的缺陷也会对强度有害。
A perspective on the issue of scale in the fracture and deformation properties of ordinarily brittle covalent–ionic solids (ceramics) is presented. Characteristic scaling dimensions for nanomechanical properties of this class of solids are identified—specimen size or layer thickness, microstructural scale, and contact dimension. Transitions in mechanical damage processes occur as the characteristic dimensions diminish from the macroscale to the submicroscale. Such transitions generally preclude unconditional extrapolations of macroscopic-scale fracture and deformation laws into the nanomechanics region. Strength of brittle solids tends to increase while toughness tends to decrease as the scaling dimensions diminish. The nature of flaws that control strength in the submicroscale region also undergoes fundamental changes—even flaws without well-developed microcracks can be deleterious to strength.