Comparison of electrochemical behavior of cast and sintered CuAg4at.% alloy during thermomechanical treatment

Abstract

The paper presents comparison of electrochemical behavior of samples of CuAg4at.% alloy obtained by powder metallurgy method and the same alloy obtained by melting and casting during oxidation in an alkaline medium. Investigated alloy exhibits anneal hardening effect, so it was examined in each stage of thermomechanical treatment resulting in this effect. Cyclic voltammetry investigations show that both sintered and cast samples after cold rolling to final reduction of 60 % behave as completely homogenous phases. In that stage of thermomechanical treatment peaks corresponding to reactions on silver do not appear and currents on cyclic voltammograms are lowest. After annealing below the recrystallization temperature both samples exhibit anneal hardening; in this stage sintered alloy retains its corrosion stability, whereas current densities for the cast alloy increase and the peaks characteristic for silver appear again. Further annealing above the recrystallization temperature leads to the increasing of current density on voltammograms for samples obtained by both methods and all characteristic current peaks for silver reappear.

Keywords

• copper
• silver
• anodic oxidation
• anneal hardening
• recrystallization