Heavily drawn Cu–Fe–Ag and Cu–Fe–Cr microcomposites

The microstructure and mechanical properties of deformation processed Cu–Fe–Ag and Cu–Fe–Cr microcomposite wires combined with intermediate heat treatments have been investigated. During cold drawing, the primary and secondary dendrite arms are aligned along the deformation axis and elongated into filaments. In Cu–Fe–Ag microcomposites, the Cu matrix is strengthened by the addition of Ag atoms and, in Cu–Fe–Cr microcomposites, the filament is strengthened by the addition of Cr atoms. The microstructural scale was found to be finer in Cu–Fe–Ag microcomposites. The finer microstructural scale in Cu–Fe–Ag can be attributed to initial finer dendrites and easier refinement of filaments due to the stronger Cu matrix. The refinement of filaments in Cu–Fe–Cr is relatively difficult due to the strengthening of filaments by the addition of Cr. The ultimate tensile strength of the Cu–Fe–Ag microcomposites was higher than those of Cu–Fe–Cr microcomposites, suggesting that the refinement of the filaments is more effective than the strengthening of the filaments in strengthening the microcomposites. The strength of Cu–Fe–Ag and Cu–Fe–Cr microcomposites is dependent on the spacing of the Fe filaments in accord with a Hall–Petch-type relationship. The fracture surfaces of all the specimens showed ductile-type fracture and iron filaments were occasionally observed on the fracture surfaces.