Effect of stacking fault energy on mechanical properties of ultrafine-grain Cu and Cu–Al alloy processed by cold-rolling

Abstract

Cu, Cu-2.2%Al and Cu-4.5%Al with stacking fault energies (SFE) of 78, 35 and 7 mJ/m2 respectively were processed by cold-rolling (CR) at liquid nitrogen temperature (77 K) after hot-rolling. X-ray diffraction measurements indicate that a decrease in SFE leads to a decrease in crystallite size but increase in microstrain, dislocation and twin densities of the CR processed samples. Tensile tests at room temperature indicate that as the stacking fault energy decreases, the strength and ductility increase. The results indicate that decreasing stacking fault energy is an optimum method to improve the ductility without loss of strength.