Equal Channel Angular Pressing to Produce Ultrafine Pure Copper with Excellent Electrical and Mechanical Properties

In this article, commercially pure copper samples were severely deformed by equal channel angular pressing (ECAP) up to eight passes at room temperature. The effects of severe plastic deformation on the microstructure, mechanical properties, and electrical conductivity of the copper were investigated. The microstructure evolution was followed by optical microscope and field emission scanning electron microscope (FE-SEM). FE-SEM shows the extreme evolution of the microstructure after four to eight ECAP passes, in which a large amount of nanoscale and ultrafine grains are observable. The mechanical properties of the pure copper in each pass were studied by compression testing and Brinell hardness method at room temperature. In this respect, hardness and yield stress increased by ~390 MPa and 75HB, respectively, after five-pass ECAP because of finer boundary spacing. The electrical conductivity measurement at room temperature showed that there was no significant change in the conductivity of the processed samples compared with the initial specimen. Hence, by applying ECAP, one can obtain the ultrafine pure copper with sub-micro-meter grain sizes that can improve mechanical properties without impairing the electrical conductivity.