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Study on Fatigue Failure of Alloyed Cu Bicrystals by means of in-situ SEM Observation

原位SEM观察铜合金双晶疲劳破坏研究

基本信息

批准号：
08455320
负责人：
KITAGAWA Kazuo
金额：
$ 4.8万
依托单位：
KANAZAWA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08455320/
关键词：
fatigue crack grain boundary structure bicrystal twin boundary molecular dynamics tilt boundary grain boundary energy 銅合金 Σ3(111)双晶境界

项目摘要

It has widely been accepted that a structure of grain boundary (GB) is one of the decisive factors affecting the GB-related phenomena such as the GB sliding, the GB corrosion and the GB stress-corrosion cracking, which are important for engineering purposes. In addition to these phenomena, fatigue behavior of materials is expected to be sensitive to the structure of the GB contained. In order to correlate the fatigue property with the GB structure, both fatigue experiments and simulations of the GB structures were carried out on the copper model bicrystals.1. The results of the fatigue investigation on copper bicrystal having a longitudinal twist boundary are summarized as follows.(1) The incompatibility of plastic strain at the GBs could induce high internal stresses in the vicinity of GBs, and apparently assists the nucleation of an intergranular fatigue crack.(2) The GB affected zone was a strong barrier against the propagation of the intragranular crack that was initiated at a free … More surface.2. In the experiments on the deviation angle dependence of the GB cracking using the copper bicrystals having the orientation relationship close to SIGMA3 (111), the following conclusions were obtained.(1) In the speciments having the deviation angles less than 3ﾟ, no any intergranular crack propagations were observed. On the other hand, the fatigue cracks often propagated along the GBs when the deviation angle increased up to 5ﾟ. Hence, it is can be said that the intergranular fatigue cracking in the copper is sensitive to the GB structure.(2) The slip step dissolution model can be applicable also for the propagation of the intergranular fatigue cracks.(3) Paths of the fatigue cracks were determined not only by the GB structure but also by the slip geometry of the constituent grains.3. The results of the molecular dynamics simulation focused on the GB structure of [110] tilt boundaries can be summarized as follows.(1) Arangements of lattice dislocations within low-angle GBs agreed well with those predicted from the differing at Burgers vector.(2) The estimated GB energy showed strong dependence on the misorientation angle between the grains. The GB energies of the low-angle boundaries were in good agreement with the theoretical values calculated from the Read-Shockley model. Less

晶界结构是影响晶界滑动、晶界腐蚀和晶界应力腐蚀开裂等晶界相关现象的决定性因素之一。除了这些现象之外，材料的疲劳行为预计对所含GB的结构敏感。为了将GB结构与疲劳性能相关联，在铜模型双金属上进行了GB结构的疲劳试验和模拟.具有纵向扭转边界的铜双晶的疲劳研究结果总结如下。(1)晶界处塑性应变的不相容性会在晶界附近产生较高的内应力，从而促进沿晶疲劳裂纹的形核。(2)晶界影响区是阻止晶内裂纹扩展的一个强有力的屏障， ...更多信息表面。在使用具有接近于SIGMA 3（111）的取向关系的铜双晶的GB裂纹的偏离角依赖性的实验中，获得了以下结论。(1)在偏离角小于3 °的试样中，没有观察到任何沿晶裂纹扩展。另一方面，当偏离角增加到5 °时，疲劳裂纹通常沿着晶界扩展。因此，可以说铜的晶间疲劳裂纹对GB组织敏感。(2)滑移台阶溶解模型也适用于沿晶疲劳裂纹的扩展。(3)疲劳裂纹的路径不仅由晶界结构决定，而且由组成晶粒的滑移几何决定.针对[110]倾斜晶界的GB结构进行的分子动力学模拟的结果可以总结如下。(1)低角度晶界内的晶格位错的排列与从不同的Burgers矢量预测的一致。(2)估计的GB能量表现出强烈的依赖于晶粒之间的取向差角。计算结果与Read-Shockley模型的理论值吻合较好。少