Role of stacking fault energy on the deformation characteristics of copper alloys processed by plane strain compression

► Different compositions of Cu–Zn and Cu–Al alloys are plane strain compressed. ► Strain hardening rates, microstructure and texture evolution are documented. ► SFE has an indirect effect rather a critical dislocation density controls twinning. ► Cu–Al exhibited the need for higher dislocation density for twin initiation. ► Onset of twinning occurs in the copper alloys tested with a normalized SFE≤10–3. Samples of Cu–Al and Cu–Zn alloys with different compositions were subjected to large strains under plane strain compression (PSC), a process that simulates the rolling operation. Four compositions in the Cu–Al system, namely 1, 2, 4.7 and 7wt.% Al and three compositions in the Cu–Zn system of 10, 20 and 30wt.% Zn, were investigated. Adding Al or Zn to Cu effectively lowers the stacking fault energy (SFE) of the alloy and changes the deformation mechanism from dislocation slipping to dislocation slipping and deformation twinning. True stress–true strain responses in PSC were documented and the strain hardening rates were calculated and correlated to the evolved microstructure. The onset of twinning in low SFE alloys was not directly related to the low value of SFE, but rather to build up of a critical dislocation density during strain hardening in the early stage of deformation (ɛ