The effect of stacking fault energy on equilibrium grain size and tensile properties of nanostructured copper and copper-aluminum alloys processed by equal channel angular pressing

Pure copper and copper-aluminum alloys (aluminum content of 2.3 at%, 7.2 at%, and 11.6 at% with stacking fault energies (SFEs) of about 48 mJ/m(2), 21 mJ/m(2), and 8 mJ/m(2), respectively) were processed by equal channel angular pressing (ECAP) at room temperature for 8 passes to generate a nanoscale grain size. The effect of SFE on microstructure refinement and tensile properties of these materials were investigated. Microstructural observations indicated that the grain size of as-ECAPed alloy decreased monotonically with increasing Al concentration, i.e. with decreasing SFE. A very low SFE was especially favorable for achieving a true nanocrystalline structure (e.g. d approximate to 57 nm in Cu-11.6 at% Al) by twinning and shear banding. The tensile strength and uniform elongation of nanostructured copper-aluminum alloys were simultaneously enhanced owing to the significant grain size refinement, solid solution strengthening and enhanced strain hardening capability. (c) 2012 Elsevier B.V. All rights reserved.