Samples of Cu, bronze (Cu–10wt%Zn) and brass (Cu–30wt%Zn) were deformed by high pressure torsion under a pressure of 6GPa for 5 rotations. The stacking fault energies of the Cu, bronze and brass were 78, 35 and 14mJ/m2, respectively, and their average grain sizes after the high-pressure torsion processing were about 84, 54 and 17nm, respectively. Deformation twins were found in all samples and their densities increased with decreasing stacking fault energy. This demonstrated that, under the same conditions of high-pressure torsion, a low stacking-fault energy promoted the formation of nanostructures and deformation twins.

Influence of Stacking Fault Energy on Nanostructure Formation under High Pressure Torsion. Y.H.Zhao, X.Z.Liao, Y.T.Zhu, Z.Horita, T.G.Langdon: Materials Science and Engineering A, 2005, 410-411, 188-93