Mechanical stability and electrical conductivity of Cu–Ag filamentary microcomposites

One of the most important features in two-phase Cu–Ag filamentary microcomposites is the abundance of interfaces compared with conventional copper-based alloys. In heavily drawn Cu–Ag filamentary microcomposites, the microstructure is extremely fine and the interphase area is too large to maintain a stable internal dislocation structure because of closely spaced filaments. Rather, most dislocations are thought to be absorbed at the interfaces as the draw ratio increases. The mechanical and electrical properties of Cu–Ag filamentary microcomposite wires were examined and correlated with the microstructural changes caused by thermomechanical treatments. The study of the electrical conductivity combined with the microstructural analyses indicates that the resistivity of Cu–Ag microcomposites is predominantly controlled by electron scattering at Cu–Ag interfaces. The substantial increase in electrical conductivity at high annealing temperatures is mainly due to dissolution and coarsening of silver filaments. The relatively low ratio of the resistivities at 293 and 77 K (ρ293 K/ρ77 K) can also be explained by the contribution of interface scattering.