Further optimization of strength and ductility in a harmonic structure designed pure copper via thermomechanical processing

In this study, thermomechanical processing (TMP) including cold rolling and subsequent annealing was applied to a novel ti-dimensional core/shell structured (Harmonic Structure, HS) pure Cu. Detailed microstructure observation by electron backscattering diffraction (EBSD) suggested that it was possible to manipulate the volume fraction and the grain size of the core/shell via TMP. Tensile tests revealed that the mechanical properties of the HS designed pure Cu can be further optimized by appropriate TMP. For instance, the ultimate tensile strength and total elongation of the TMP30% sample (CR30%+annealing at 673 K for 1.8 ks) were 279 MPa and 51%, respectively, which were simultaneously higher than those of the original HS sample. The underlying mechanisms for the improved strength and ductility in the TMP processed samples were discussed based on the change of microstructures during cold rolling and annealing.