Effect of Sample Size and Crystal Orientation on the Fatigue Behaviour of Single Crystalline Microbeams
Effect of Sample Size and Crystal Orientation on the Fatigue Behaviour of Single Crystalline Microbeams
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DOI：
10.3390/ma13030741
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发表时间：
2020-02
期刊：
影响因子：
3.4
通讯作者：
Jorge Rafael Velayarce;C. Motz
中科院分区：
文献类型：
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作者：
Jorge Rafael Velayarce;C. Motz
梁偏转实验被用来系统地研究尺寸效应的低周疲劳（LCF）变形行为的微尺寸弯曲梁的铜（Cu）单晶定向为单滑移，临界和共面双滑移。我们给出了尺寸在1到15 μm之间的微尺寸梁的循环硬化曲线和疲劳表面粗糙度，以及位错结构。循环硬化曲线、表面粗糙度和位错显微组织都有明显的晶体取向和尺寸效应。根据实验结果，在单一滑移方向的疲劳损伤明显减少，随着样品尺寸的减小，但是，低于临界尺寸制度，表面损伤突然增加。此外，尺寸大于5 μm的样品清楚地显示，除了PSB样结构外，与较小的样品相比，扭结带的出现导致更大的表面粗糙度。与单滑移取向相比，临界双滑移取向的微晶中的疲劳表面损伤变得更加普遍。定量地，疲劳表面损伤的相关性也被证明与PSB样结构的形成。
Beam deflection experiments were used to systematically examine size effects on the low cyclic fatigue (LCF) deformation behaviour of micro-sized bending beams of copper (Cu) single crystals oriented for single slip, critical and coplanar double slip. We present cyclic hardening curves and fatigue surface roughness, as well as dislocations structures of the micro-sized beams with sizes between 1 and 15 µm. A clear crystal orientation and size effect on the cyclic hardening curves, surface roughness, and the dislocation microstructures were observed. Based on the experimental results, the fatigue damage in single slip orientations clearly decreased with decreasing the sample size, however, below a critical size regime, the surface damage suddenly increases. Additionally, samples with sizes larger than 5 µm clearly revealed, besides PSBs-like structures, the emergence of kink bands leading to larger surface roughness in comparison to the smaller ones. Fatigue surface damages in microcrystals oriented for critical double slip became more prevalent compared to single slip orientations. Quantitatively, the correlation of the fatigue surface damage was also demonstrated with the formation of PSBs-like structures.