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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.
Due to its unique microstructure and properties, ultrafine grained materials have aroused a great deal of attention. However, due to the tendency of strain localization and dynamic recrystallization during cyclic deformation, large-scale shear bands and severe grain coarsening occur, The intrinsic fatigue behavior of ultrafine-grained materials has not been well understood.In this study, the ideal equiaxed ultrafine grained microstructure was prepared by friction stir processing (FSP) in pure copper, and the research on its high-cycle fatigue behavior , FSP pure copper fatigue limit and fatigue ratio compared with other ultrafine grained pure copper significantly improved, and fatigue did not appear large-scale shear bands and severe grain coarsening, fatigue damage mainly dominated by the extrusion mechanism In the ultrafine scale, dislocation related activities still predominate, but they are confined to ultrafine grain, and no regular dislocation structure is found in the coarse grain.