Thermo-mechanical processing and properties of Cu–Fe–Cr microcomposites

Thermo-mechanical treatments have been employed in this study to optimize the strength and conductivity of Cu–Fe–Cr microcomposites. The ultimate tensile strength (UTS) and the conductivity of Cu–Fe–Cr wires drawn to the cold drawing strain η=4.8 without intermediate heat treatments (NH) were observed to be 920 MPa and 33.8% IACS, respectively, and those with heat treatments (IH-2) were 891 MPa and 41% IACS. Further drawing wires to the cold drawing strain η=6.3 after an additional heat treatment increased the conductivity from 43.1 to 53.3% IACS with a slight increase of hardness. The precipitation of impurities and alloying elements during intermediate heat treatments is thought to increase the conductivity due to the reduced impurity scattering. The activation volumes for deformation increased from 138b3 in the as-drawn wire to 230b3 in the wire annealed at 500 °C. Numerous particles were observed in Cu matrix and the spacing between these particles were found to be slightly smaller than the activation length (138b=35 nm). The most probable rate controlling mechanism of Cu–Fe–Cr microcomposites is suggested to be the interaction between dislocations and precipitates in Cu matrix.