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.