Influence of stacking fault energy on nanostructure formation under high pressure torsion

Copper, bronze (Cu-10 wt.% Zn) and brass (Cu-30 wt.% Zn) were deformed by high pressure torsion (HPT) under a pressure of 6 GPa for five rotations. The stacking fault energies (SFEs) of copper, bronze and brass are 78, 35 and 14 mJ/m2, respectively, and their average grain sizes after the HPT processing were about 84, 54 and 17 nm, respectively. Deformation twins were found in all samples and their densities increased with decreasing SFE. This work demonstrates that under the same conditions of HPT a low SFE promotes the formation of nanostructures and deformation twins.