Fatigue cracking at twin boundaries: Effects of crystallographic orientation and stacking fault energy
Fatigue cracking at twin boundaries: Effects of crystallographic orientation and stacking fault energy
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DOI：
10.1016/j.actamat.2012.02.016
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发表时间：
2012-04-01
期刊：
影响因子：
9.4
通讯作者：
Zhang, Z. F.
中科院分区：
文献类型：
--
作者：
Zhang, Z. J.;Zhang, P.;Zhang, Z. F.
研究了晶体取向和层错能对Cu、Cu-Al和Cu-Zn合金低周疲劳（LCF）下孪晶界开裂行为的综合影响。基于Sigma 3 TB在面心立方材料中的晶体学特征，提出了一种新的方法--滑移形态法，通过研究LCF试验后试样表面的孪晶滑移形态特征来确定晶粒取向。通过分析位错TB相互作用及其对TB的损伤，提出了一个新的描述晶体取向对TB低周疲劳开裂行为影响的参数--Schmid因子差（DSF）。通过对纯铜、Cu-Al和Cu-Zn合金百余种疲劳后表面形貌的系统研究，建立了DSF、SFE、位错滑移模式与TB开裂临界条件之间的半定量关系。有趣的是，发现TB破解强烈依赖于DSF和SFE的合作。考虑滑移位错与不同界面的相互作用，对几种典型界面的疲劳开裂可能性进行了比较和讨论。结果表明，小角度晶界对疲劳裂纹的抵抗能力最强，大角度晶界最弱，而晶界对疲劳裂纹的抵抗能力介于两者之间，对材料的疲劳性能贡献最大。这一新发现将有助于理解循环载荷下的界面性能，并可能有利于未来设计具有最佳疲劳性能的高性能材料。(C)2012 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
The combined effects of crystallographic orientation and stacking fault energy (SFE) on the cracking behaviors of twin boundaries (TB) under low-cycle fatigue (LCF) tests were studied in pure Cu, Cu-Al and Cu-Zn alloys. A new approach, called the slipping morphology method, based on the crystallographic characteristics of Sigma 3 TB in face-centered cubic materials, was developed to determine the grain orientations by studying the twin-slip morphology characteristics on the sample surfaces after LCF tests. Through analyzing the dislocation TB interaction and the damage this causes to TBs, a new parameter, defined as the difference of Schmid factors (DSF), was proposed to describe the effects of crystallographic orientation on the LCF cracking behaviors of TBs. A semi-quantitative relationship was established among DSF, SFE, dislocation slip mode and the critical conditions of TB cracking by systematically studying more than a hundred post-fatigue surface morphologies of pure Cu, Cu-Al and Cu-Zn alloys. It is interesting to find that the TB cracking relies strongly on the cooperation of both DSF and SFE. Furthermore, taking into account the interactions between slip dislocations and different boundaries, the fatigue cracking possibilities of several typical interfaces were compared and discussed. The results demonstrate that low-angle grain boundaries (GBs) are the strongest in resisting fatigue cracking, high-angle GBs are the weakest, and TBs are in between, which contributes the most to the final fatigue performance of materials. This new finding will help understanding of the interfacial properties under cyclic loading and may be beneficial to the design of high-performance materials with optimal fatigue properties in the future. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.