Effect of trace alloying elements on thermal stability and electrical conductivity of pure copper
Effect of adding trace alloying elements on thermal stability of grain size and electrical conductivity of 4N pure copper was studied using optical microscope(OM),transmission electron microscopy(TEM)and electrical conductivity testing.The interaction between alloying elements and trace impurity element S in the matrix was analyzed.The results show that both the addition of trace Ti element and co-addition of trace Cr,Ni and Ag elements can significantly improve the thermal stability of the grain size of the 4N pure copper.After high-temperature treatment at 900 ℃ for 30 min,,the grain sizes of the Cu,Cu-Ti,and Cu-Cr-Ni-Ag are 158.57,86.06 and 48.35 μm,respectively,shows the thermal stability is Cu-Cr-Ni-Ag>Cu-Ti>Cu.Meanwhile,the electrical conductivity of the 4N pure copper remains high after adding trace alloying elements,and the electrical conductivity of the Cu,Cu-Ti and Cu-Cr-Ni-Ag is 101.87%IACS,101.64%IACS and 99.98%IACS,respectively.Analysis suggests that the improvement of thermal stability is mainly related to the pinning effect of TiS phase and CrS phase,as well as the solid solution drag effect of Ni and Ag.Trace Ti and Cr elements can react with impurity S to form hexagonal TiS phase and monoclinic CrS phase,both of which exhibit a non-coherent relationship with the matrix,especially the CrS phase is smaller and more numerous than TiS phase.
pure coppertrace alloying elementconductivitythermal stabilityprecipitated phase