Strain localization and ductile fracture mechanism of micro/mesoscale deformation in ultrafine-grained pure copper

To realize the application of ultrafine-grained (UFG) materials in micro-forming, the micro/mesodeformation and fracture behavior of UFG pure copper processed using equal-channel angular pressing were analyzed by making in/ex-situ observations during tensile testing. The evolution of surface cracks and inner voids was apparent in the in-situ scanning electron microscopy (SEM) images and synchrotron radiation X-ray tomograms, respectively. The results indicate that the surface-crack evolution of UFG pure copper can be correlated with strain localization when the flow stress decreases after peaking. The effects of grain size and shear texture on damage evolution during the fracture process are also discussed. This work comprehensively explores the plasticity and fracture/failure mechanisms in UFG Cu samples during the micro-forming process.& COPY; 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).