Effect of annealing processes on microstructure, mechanical properties and conductivity of Cu-12%Ag alloy composite-reinforced by fibers

The Cu-12wt.%Ag microcomposite was prepared by heavy cold drawing and intermediate heat treatment. The influence of isothermal processes on the microstructure and properties of the alloy was investigated at various temperatures for different annealing time. Isothermal treating at 200 degrees C fails to change the fibrous morphology of the strengthened phase and results in the slightly decreased ultimate tensile strength and slightly increased electrical conductivity. Isothermal annealing treating at 300 degrees C results in a partial migration of the phase interface. The electrical conductivity obviously increases and the ultimate tensile strength evidently decreases in an initial isothermal annealing period. After this, the increase of the electrical conductivity and the decrease of the ultimate tensile strength become slow. Isothermal annealing treating at 400 degrees C promotes the significant recrystallization and the grain propagation in the deformed structure. The electrical conductivity greatly increases and the ultimate tensile strength severely loses in an initial isothermal period. With prolonging isothermal annealing time, the ultimate tensile strength loses slowly and the electronic conductivity also shows a slow reduction after reaching a maximum value. The factors of recovery, recrystallization, precipitation of secondary particles, dissolution of the solute atoms, etc. in the fibrous structure during isothermal annealing processes can be used to explain the changes of microstructure and properties of the alloy.