Achieving an exceptional ductility at room temperature in a low SFE copper alloy fabricated by severe plastic deformation

Abstract

Abstract Low stacking fault energy alloys often exhibit low ductility. However, sometimes these alloys show unusual mechanical behavior following specific processing parameters. In this study, a low stacking fault energy α+β brass was processed by equal channel angular pressing (ECAP) at 350 °C in ‘route C’ through three passes. Room temperature tensile testing showed that ductility, surprisingly, reached ~80%, whilst good tensile strength was maintained. Investigation of alloy microstructure revealed a combination of deformation mechanisms, including slip and twinning, accompanied by grain boundary serration and grain fragmentation. It is suggested that these deformation modes triggered these unexpected mechanical properties in this intrinsically brittle alloy. The required energy for discontinuous recrystallization was supplied after only one pass in the α phase, and three passes in the β phase, which then prompted good ductility. In order to study texture evolution, the macro-texture was measured. A high fraction of recrystallized grains and change in strain path fostered the development of Goss, Rotated Goss and Rotated Cube components in the α phase. While in the β phase {011} and Goss components were dominant. Despite the high Schmid factor, Hall-Petch effects and work hardening led to increase of strength and hardness after the final pass.