Efficiency of the refinement by deformation twinning in wire drawn single phase copper alloys

The microstructure of single phase copper alloys is altered by cold deformation. Depending on the processing parameters like temperature and intrinsic material parameters as stacking fault energy, the dominant deformation mechanism is different and the refinement of the microstructure bears other rates with respect to the deformation strain. The formation of deformation twins is activated at low homologous temperature or at low stacking fault energy. Both also lead to smaller grain sizes achieved at a certain deformation strain. Lowering the temperature only yields to a high efficiency in strain hardening with respect to room temperature deformation for intermediate stacking fault energies. The maximum efficiency is found to occur in the vicinity of the onset of deformation twinning at room temperature which was found for a stacking fault energy of 30 mJ/m2. The thermal stability of the microstructure is assessed by means of in situ resistivity measurements.