Effective grain refinement of pure Cu processed by new route of equal channel angular pressing

Microstructures and mechanical properties of pure Cu processed by equal-channel angular pressing (ECAP) at room temperature (RT) were investigated. Samples were subjected to eight passes using routes B-c, A and X. A new route which is called route X was proposed in this paper. Route X has a specific rotation angle of the sample between consecutive passes to maintain the angle between the shear plane (SP) and grain elongation plane (EP) equal to the angle between adjacent faces of {111} slip plane in each pass. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were utilized to investigate the deformed microstructure. The ultrafine grained (UFG) bulk pure Cu was fabricated by three different routes for eight passes. The TEM and XRD results revealed that dislocation density and grain size are both lower using route X after eight passes. The results of the tensile tests at RT showed that route X has better strength and elongation than routes A and B-c processed samples, which is attributed to the lower dislocation density and smaller grain size with mostly high angle grain boundaries using route X. Furthermore, the fracture mechanism of ECAPed samples was discussed.