Excellent strength and electrical conductivity achieved by optimizing the dual-phase structure in Cu–Fe wires

Abstract

Cu–Fe alloy wire with high strength, moderate electrical conductivity and low cost, has a promising application prospect in the electrical industry. In this study, high performance Cu80Fe20 wires were prepared by annealing and drawing at room temperature (RT). Based on the X-ray diffraction and electron microscopy characterization, the influence of microstructural parameters on the mechanical properties and electrical conductivity of the wires were analyzed. The pre-annealing at 500 °C, resulted in the nanoparticles precipitation of Cu in Fe-phase and Fe in Cu-phase, respectively. The drawing deformation greatly improved the strength of wires, while did not result in a significant reduction in the electrical conductivity. Cu nanoprecipitation promoted the refinement of the Fe-phase during deformation, which result in a nano lamellar structure of the Fe-phase with an average boundary spacing as low as 50 nm. Dynamic recovery and recrystallization of the Cu-phase were observed to occur during the drawing at RT with the <112> texture and annealing twinning. The plasticity and electrical conductivity of the Cu-phase were greatly preserved due to the drawing-induced dynamic recovery and recrystallization. Moreover, the strength of the wire was greatly enhanced by the formation of a nano-lamellar structure in the Fe-phase. Hence, the alloy wire at a strain of 3.94 had a high tensile strength of 863 MPa (125% higher than the original strain-free wire), a total elongation of 5%, and the electrical conductivity reached 47 %IACS (only 8 %IACS lower than the original strain-free wire), which shows higher cost properties than other copper alloys.