Influence of stacking fault energy on the mechanical properties in cold-rolling Cu and Cu–Ge alloys

Cu, Cu–0.1 at.%Ge and Cu–5.7 at.%Ge with stacking fault energies (SFEs) of 78, 54, and 15 mJ/m2, respectively, were processed by cold-rolling at the liquid nitrogen temperature. X-ray diffraction measurements indicate that decreasing SFE decreases the average grain size but increases the microstrain, dislocation density, and twin density in the cold-rolled samples. Tensile testing results show that the strength and ductility of the materials increase simultaneously with decreasing SFE. The relationship between the structure and mechanical properties of the materials is briefly discussed.

► Cu, Cu–0.1 at.%Ge and Cu–5.7 at.%Ge were processed by cold-rolling (CR) at liquid nitrogen temperature.
► A decrease in SFE leads to a decrease in crystallite size, an increase in microstrain, in dislocation and in twin densities for the CR processed samples.
► Tension tests of Cu and Cu–Ge alloy with different SFE have shown that with decreases of SFE, the strength and ductility increase simultaneously.