Effect of Y addition on microstructure evolution and precipitation of Cu-Co-Si alloy during hot deformation

Abstract The effects of Y for the microstructure evolutions of Cu-Co-Si alloys during hot deformation were investigated. The hot deformation behaviors for Cu-2.6Co-0.65Si and Cu-2.6Co-0.65Si-0.2Y alloys were carried out on the Gleeble-1500 simulator with the strain rates from 0.001 to 10 s−1 and temperatures from 500 °C to 900 °C. The hot deformation activation energies for two copper alloys were calculated and the constitutive equations were also established. According to the true stress-strain curves and EBSD image analysis, it showed that the nucleation of dynamic recrystallization (DRX) grain and the growth of DRX grain were promoted with the addition of 0.2 wt% Y. Electron backscatter diffraction (EBSD) was used to characterize the microstructure of the hot deformed Cu-Co-Si alloy. The electrode diagram and ODF diagram were established to analyze the textures. The texture strength and the number of small angle grain boundaries were reduced by the addition of 0.2 wt% Y. The microstructure of two alloys was analyzed by transmission electron microscopy, it was found that a large number of Co2Si nanoparticles were distributed on the copper matrix. Y could promote the precipitation process of δ-Co2Si, and these nanoparticles interacted with dislocations during the hot deformation process to improve the deformation resistance.