1 Department of Wind Energy, Technical University of Denmark2 Materials science and characterization, Department of Wind Energy, Technical University of Denmark3 Department of Mechanical Engineering, Technical University of Denmark4 Materials and Surface Engineering, Department of Mechanical Engineering, Technical University of Denmark5 Risø National Laboratory for Sustainable Energy, Technical University of Denmark6 Shenyang National Laboratory for Materials Science
Recrystallization and mechanical behavior of nanocrystalline copper prepared by dynamic plastic deformation (DPD) and DPD with additional cold-rolling (DPD+CR) were investigated, with an emphasis on the effects of heterogeneity within the deformation microstructure. The DPD sample was found to develop a heterogeneous structure, consisting of regions with different textures and microstructures. This heterogeneity within the deformed structure leads to the formation of severely clustered grains in partially recrystallized samples. The recrystallization kinetic curve shows an Avrami exponent less than 1, which is explained using a two-stage kinetics model incorporating the heterogeneity. The heterogeneity of the DPD sample is largely reduced by applying additional rolling. This change in deformation path leads to a more random distribution of the recrystallized grains and more conventional recrystallization kinetics. The hardness of the two samples was measured, and the mechanical properties before and after partial recrystallization of both samples are discussed based on the presence of structural heterogeneities on the macroscopic and the microscopic scale.