Research on the twinning growth mechanism induced by self-annealing of electrolytic copper foil with special phase structure

During self-annealing of electrolytic copper foil, residual stress release induces twin formation via recrystallization, significantly affecting the microstructure and macroscopic properties. The evolution of morphology, texture, and microstructure during the self-annealing process of 4.5 μm thick electrolytic copper foil was analyzed in detail, and the formation of double crystals induced by recrystallization was systematically investigated. The results indicate that during the self-annealing process, the quantity and density of twinned grains increase with time, reaching a plateau after 168 h. Moreover, the formation of twinned grains promotes the improvement of the mechanical properties and corrosion resistance of copper foil. Further analysis reveals that when grains oriented along the (1 1 1) and (2 0 0) crystal planes are adjacent and grow repeatedly, the content of twinned grain at the end of the self-annealing process correlates with the sum of the texture coefficients of the (1 1 1) and (2 0 0) crystal planes. This study provides a theoretical foundation for the precise control of twinning formation behavior during the self-annealing process of electrolytic copper foil.