Effects of Temperature and Strain Rate on Plastic Deformation of Ultrafine-Grained Copper Prepared by Equal-Channel Angular Pressing

Abstract

Ultrafine-grained (UFG) pure copper of 280 nm grain size was prepared by equal-channel angular pressing. Tensile tests, strain-rate change tests and temperature change tests were conducted on UFG Cu in the temperature range between 77 K and 373 K. As usual, tensile strength increased as temperature decreased and strain rate increased. The activation energy of deformation increased linearly with the increase in temperature. On the other hand, the activation volume first increased with the increase in temperature from 77 K to about 200 K while it decreased with temperature above 200 K. Therefore, the activation volume shows the maximum value of 180 b³ at about 200 K. These experimental results are discussed by considering two different thermally-activated deformation processes.