Effect of nano-scaled Al2O3 particles on dynamic recrystallization behavior and microstructure evolution of pure copper in hot deformation

Abstract

The unusual dynamic recrystallization (DRX) behavior and microstructure evolution during compression deformation at 400–800 °C of a Cu–Al2O3 alloy were investigated herein. The calculation of activation energy (Q) and critical strain for DRX (εc), as well as the prediction of the volume fraction of DRX, are achieved through the construction of constitutive equations and a kinetic model of DRX. The nano-scaled Al2O3 particles are found to exert a significant pinning effect on dislocations and grain boundaries, significantly increasing the dislocation density. The Cu–Al2O3 exhibits a higher work hardening rate and stress compared to pure Cu under the same deformation conditions. The peak stresses of Cu–Al2O3 at 400 °C and 800 °C are 319.7 MPa and 155.4 MPa, respectively, 80.4 % and 243.1 % higher than those of pure Cu. The addition of nano-scaled Al2O3 particles reduces Q and εc of DRX, promoting the transition from low-angle to high-angle grain boundaries during high-temperature deformation. Additionally, distortion zones induced by Al2O3 particles as potential nucleation sites for DRX. While the addition of these particles promotes DRX of pure Cu, the initial DRX rate of Cu–Al2O3 is suppressed by the strong pinning effect of Al2O3 particles.