Strain-Induced Balancing of Strength and Electrical Conductivity in Cu-20 wt% Fe Alloy Wires: Effect of Drawing Strain

Abstract

The effects of drawing strain during intermediate annealing on the microstructure and properties of Cu-20 wt% Fe alloy wires while maintaining constant total deformation were investigated. Intermediate annealing effectively removes work hardening in both the Cu matrix and Fe fibers, restoring their plastic deformation capacity and preserving fiber continuity during subsequent redrawing. The process also refines the Fe phase, leading to a more uniform size distribution and straighter, better-aligned Cu/Fe phase interfaces, thereby enhancing the comprehensive properties of the alloy. The magnitude of drawing strain during intermediate annealing plays a critical role in balancing the mechanical strength and electrical conductivity of redrawn wires. A lower initial drawing strain requires greater redrawing strain, leading to excessive hardening of the Fe fibers, which negatively impacts the electrical conductivity and tensile plasticity. Conversely, a higher initial drawing strain can result in insufficient work hardening during the redrawing deformation process, yielding minimal strength improvements. Among the tested alloys, H/3.5 wires show a slight reduction in strength and hardness compared to W and H/4.5 wires but exhibit a significant increase in tensile elongation and electrical conductivity. The tensile strength was 755 MPa, and the electrical conductivity was 47% international-annealed copper standard (IACS). The optimal performance is attributed to the formation of a high-density, ultrafine Fe fiber structure-aligned parallel to the drawing direction, which is achieved through a suitable combination of the drawing process and intermediate annealing.