Abstract
Ultrafine grained (UFG) materials have attracted considerable attention owing to their unique microstructure and mechanical properties. However, the easy formation of large-scale shear bands and severe grain coarsening during cyclic deformation gives rise to enormous difficulties when investigating the intrinsic fatigue behavior of UFG materials. Herein, we discuss the fabrication of an ideal model material, based on pure Cu, by friction stir processing (FSP), which exhibits equiaxed ultrafine grains, low dislocation density, and a high ratio of high-angle grain boundaries. This model material was used to investigate the intrinsic high cycle fatigue behavior of UFG material. It was found that an enhanced fatigue limit and fatigue ratio can be achieved by FSP Cu due to its uniform and stable UFG structure. Instead of traditional large-scale shear bands, protrusion was found to be the main surface damage morphology for FSP Cu during high cycle fatigue deformation, and no obvious grain coarsening was observed. Dislocation related activity also dominated, but was limited to the ultrafine grains without the formation of regular dislocation structures.
摘要
超细晶材料由于独特的组织和性能引起了广泛的关注, 然而由于在循环变形过程中极易发生应变局部化和动态再结晶, 导致产生大尺度剪切带和严重的晶粒粗化, 使得人们对超细晶材料的本征疲劳行为一直缺乏深入认识. 本研究利用搅拌摩擦加工(FSP)方法在纯铜中制备出理想的等轴超细晶组织, 对其高周疲劳行为的研究表明, FSP纯铜的疲劳极限和疲劳比与其他超细晶纯铜相比明显提高, 而且疲劳后没有出现大尺度的剪切带和严重的晶粒粗化, 疲劳损伤主要以挤出机制为主. 在超细晶尺度内, 位错相关的活动仍然占主导, 但仅局限于超细晶内部, 没有形成粗晶中常见的规则位错结构.
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Peng Xue is an associate professor at Shenyang National Laboratory for Materials Science at the Institute of Metal Research, Chinese Academy of Sciences. His research focuses on the friction stir welding and processing, and the mechanical properties of ultrafine grained materials.
Zongyi Ma is a professor at Shenyang National Laboratory for Materials Science at the Institute of Metal Research, Chinese Academy of Sciences. His research focuses on the advanced metal matrix composite, friction stir welding and processing, and superplastic deformation behavior of fine grained materials. He authored and co-authored more than 240 international journal publications with citations more than 6,300.
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Xue, P., Huang, Z., Wang, B. et al. Intrinsic high cycle fatigue behavior of ultrafine grained pure Cu with stable structure. Sci. China Mater. 59, 531–537 (2016). https://doi.org/10.1007/s40843-016-5068-6
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DOI: https://doi.org/10.1007/s40843-016-5068-6