Recrystallization of deformed copper - kinetics and microstructural evolution

The objective of this study is to investigate the recrystallization kinetics and microstructural evolution in copper deformed to high strains, including copper deformed by cold-rolling and copper deformed by dynamic plastic deformation (DPD). Various characterization techniques were used, including electron backscatter diffraction (EBSD), Vickers hardness test, 3D X-ray diffraction (3DXRD) and differential scanning calorimetry (DSC).
For the cold-rolled samples, a series of initial parameters was investigated for their effects on the recrystallization kinetics and textures, including initial grain size, sample widening, strain, annealing temperature, impurity content, storage time, etc. The recrystallization in the cold-rolled samples with coarse and fine initial grain sizes is the focus of the present study. It is found that a strong cube recrystallization texture is only developed in the initially fine grained sample. The strong cube texture is related to a few extremely large cube grains, named supercube grains in this study. The development of supercube grains is compared with that of the other cube grains and noncube grains.
Recrystallization in the DPD sample with and without additional rolling was investigated. The spatial distribution of the recrystallizing grains is very different: severely clustered in the DPD sample versus a more random distribution in the one with additional rolling. This difference is inherited from the deformation structures. The effects of annealing on the mechanical properties are also discussed.
The recrystallization kinetics in all the samples investigated in this study shows relatively low Avrami exponents. The average growth rates of the recrystallizing grains are found to decrease with time. The growth curves of individual recrystallizing grains also show decreasing growth rates. The effects of the variation within the deformation structures on various length scales on the recrystallization kinetics are discussed.