Tensile behavior and deformation mechanisms of bulk ultrafine-grained copper
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The tensile behaviors of the ultrafine-grained (UFG) pure copper prepared by cold rolling have been investigated. The UFG-Cu exhibited high strengths and low ductility. The ductile dimple-like fracture surfaces and persistent-slip-bands (PSBs)-like local shear bands in the tension-deformed UFG-Cu were observed, both of which typically spanned tens of grain sizes. This observation indicated that the fracture mechanisms operated at a larger scale than the grain size and eventually involved collective grain activities. Moreover, localized shear bands provided the experimental evidence to the localized plastic deformation, which was the one of the dominant reasons, causing the low ductility in the UFG-Cu.
KeywordsShear Band Dislocation Activity Dimple Size Local Shear Band Linear Intercept Method
The present work was supported by the NSF International Materials Institutes (IMI) Program, under DMR-0231320, with Dr. Carmen Huber as the Program Director.