Microstructural Evolution and Micro-Compression in High-Purity Copper Processed by High-Pressure Torsion

Pure copper is subjected to severe plastic deformation at room temperature using quasi-constrained high-pressure torsion through 1/4 to 10 turns. The evolution of the microstructure is monitored using X-ray diffraction and electron backscatter diffraction. Specimens are analyzed both before and after micro-compression of ≈50%. The results show that after 10 turns there is a homogeneous ultrafine-grained (UFG) microstructure with an average grain size of ≈250 nm and with a simple shear texture. The micro-compression testing shows that UFG specimens exhibit a better surface quality after compression thereby demonstrating an excellent potential for using UFG copper in micro-forming.