Strain softening induced by high pressure torsion in copper alloys

Abstract

Three kinds of Cu-Al alloys and a pure Cu sample with different stacking fault energies (SFEs) are deformed using room temperature rolling (RR) and high pressure torsion (HPT), respectively. The microstructure is analysed by means of transaction electron microscopy and Xray diffraction. It is found that HPT is more feasible to obtain nanocrystals and profuse twins. Tailoring the SFE can promote sample strength without sacrificing the ductility of the Cu alloys. The tensile properties of samples processed by HPT and RR are compared. It is discovered that the HPT process leads to the strain softening phenomenon in samples with relatively high SFE. The excellent mechanical properties can be obtained in samples deformed by HPT with a SFE of 6mJ/m2, in which strain softening was restrained and strain hardening played a dominant role in the deformation process. The relationship between tensile properties and microstructures of the deformed metals is also investigated.