Effects of CeCu₆ and Cu₂S on microstructure and properties in pure copper

The effects of CeCu₆ and Cu₂S on microstructure, electrical conductivity and mechanical properties in as-cast pure copper were investigated by utilizing the microstructure analysis, conductivity test and tensile test with adding 300 ppm Ce and S elements in pure copper ingot (Ce and S elements, mainly existed in the form of CeCu₆ and Cu₂S). The results showed that the average grain sizes of as-cast pure copper, Cu-0.03Ce and Cu-0.03S were 376, 159 and 193 μm, respectively. The grain refining mechanism of the two phases (CeCu₆ and Cu₂S) were quite different. The grain refining mechanism of CeCu₆ mainly rely on component supercooling; The grain refining mechanism of Cu₂S mainly rely on inhibiting grain growth. After hot extrusion, the conductivity of as-cast pure copper, Cu-0.03Ce and Cu-0.03S were increased from 100.1, 100.2 and 95.5 to 101.3, 100.9 and 99.4 %IACS; and the elongation were 66.59, 49.17 and 34.23%, respectively. The disregistry between CeCu₆/Cu₂S and copper matrix was 10.24% (0 2 10¯)_CeCu6‖(4¯ 11)_Cu, 24.91% (14¯ 6 12)_Cu2S‖(1¯ 31)_Cu, respectively. The disregistry between CeCu₆ and copper matrix was smaller than that between Cu₂S and copper matrix, leading to the wettability, conductivity and interfacial bonding strength between CeCu₆ and copper matrix were better. The conductivity of Cu-0.03S could be improved after hot extrusion, which attributed to the gap at the interface could be partially reduced by hot extrusion.