Role of plasticity on interface crack initiation from a free edge and propagation in a nano-component
Role of plasticity on interface crack initiation from a free edge and propagation in a nano-component
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DOI：
10.1007/s10704-007-9079-0
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发表时间：
2007-10
影响因子：
2.5
通讯作者：
H. Hirakata;Y. Takahashi;D. Truong;T. Kitamura
中科院分区：
文献类型：
--
作者：
H. Hirakata;Y. Takahashi;D. Truong;T. Kitamura
为了阐明塑性在纳米构件中自由边缘裂纹萌生和裂纹扩展过程中的作用，采用提出的纳米悬臂弯曲方法和改进的四点弯曲方法对韧性Cu和脆性Si组成的试样进行了分层实验。采用有限元方法对裂纹萌生和扩展临界载荷下Cu/Si界面应力场进行了分析。结果表明，尽管Cu/Si界面相同，但界面边缘和裂纹尖端附近的弹性应力强度却有很大差异。基于原位透射电镜测量的纳米悬臂挠度，估计了Cu的塑性。塑性影响应力场；界面边缘附近的法向应力增大，而裂纹尖端附近的法向应力减小。两者的弹塑性应力在约10nm范围内接近。这表明界面的局部断裂，即裂纹在界面边缘的起裂和沿界面的扩展，受10 nm量级的弹塑性法向应力控制。
In order to elucidate the role of plasticity on interface crack initiation from a free edge and crack propagation in a nano-component, delamination experiments were conducted by a proposed nano-cantilever bend method using a specimen consisting of ductile Cu and brittle Si and by a modified four-point bend method. The stress fields along the Cu/Si interface at the critical loads of crack initiation and crack propagation were analyzed by the finite element method. The results reveal that intensified elastic stresses in the vicinity of the interface edge and the crack tip are very different, although the Cu/Si interface is identical in both experiments. The plasticity of Cu was then estimated on the basis of the nano-cantilever deflection measured by in situ transmission electron microscopy. The plasticity affects the stress fields; the normal stress near the interface edge is intensified while that near the crack tip is much reduced. Both the elasto-plastic stresses are close to each other in the region of about 10 nm. This suggests that the local interface fracture, namely, the crack initiation at the interface edge and the crack propagation along the interface, is governed by elasto-plastic normal stress on the order of 10 nm.