Evaluation of Fatigue Crack Propagation of Sn-5.0Sb/Cu Joint Using Inelastic Strain Energy Density
Evaluation of Fatigue Crack Propagation of Sn-5.0Sb/Cu Joint Using Inelastic Strain Energy Density
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DOI：
10.2320/matertrans.mh201813
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发表时间：
2019-01-01
影响因子：
1.2
通讯作者：
Kariya, Yoshiharu
中科院分区：
文献类型：
--
作者：
Nakajima, Yuta;Ono, Keisuke;Kariya, Yoshiharu
本文采用有限元法计算Sn-5.0Sb/Cu接头裂纹尖端处的非弹性应变能密度W-in，对其疲劳裂纹性能进行了评价。Win-c由w乘以w得到，w是由裂纹尖端周围任意大小的正方形区域乘以正方形区域的边长得到的，Win-c不依赖于正方形区域的大小和单元尺寸。疲劳裂纹在钎料层内扩展，其疲劳裂纹扩展速率与δ Win-c之间符合Paris律型的幂律。然而，疲劳裂纹扩展规律中的幂指数随Delta Win-c区域的不同而不同。在低δ - Win-c区域，幂指数约为1，在高δ - Win-c区域，幂指数非常大。在低δ Win-c区，疲劳断裂沿裂纹前方由连续动态再结晶形成的高角度晶界扩展。另一方面，在高δ Win-c区，断裂转变为静态断裂模式，出现解理断裂。高δ Win-c区域的大幂指数归因于解理断裂。
In this study, evaluation of fatigue crack properties in the Sn-5.0Sb/Cu joint was performed by using the inelastic strain energy density W-in around the crack tip which was calculated by FEM. Win-c given by the multiplication of W-in obtained from an arbitrary-sized square region surrounding the crack tip by the side length of the square region-did not depend on the size of the square region and the element size. The fatigue crack propagated in the solder layer and the power law of Paris law type between its fatigue crack propagation rate and Delta Win-c held. However, the power exponent in the fatigue crack propagation law differed depending on the regions of Delta Win-c. The power exponent became about 1 in the low Delta Win-c region and very large in the high Delta Win-c region. In the low Delta Win-c region, fatigue fracture propagated along the high angle grain boundaries formed ahead of the crack by the continuous dynamic recrystallization. On the other hand, the fracture transformed to static fracture mode in the high Delta Win-c region and the cleavage fracture was observed. The large power exponent in the high Delta Win-c region was attributed to the cleavage fracture.