Improvements in properties of sintered and cast Cu–Ag alloys by anneal hardening effect

Abstract

Copper and copper alloys containing 4 at.-% of silver were prepared by the cast method and by the powder metallurgy process. Sintered and cast samples of copper and alloys were subjected to the same thermomechanical treatment. Annealing up to recrystallisation temperature was performed, followed by hardness and electrical conductivity measurement. This investigation shows that the hardness and electrical conductivity of cold deformed Cu–4Ag alloys increase after annealing in the temperature range of 160–400°C due to the anneal hardening effect. It is shown that the amount of strengthening (caused by anneal hardening) increases with the increasing degrees of predeformation and that the increase of strength is more pronounced in the sintered than in the cast Cu–4Ag alloy. The electrical conductivity of the sintered alloy increases with the degrees of cold rolling, whereas the electrical conductivity of the cast alloy decreases. During annealing the electrical conductivity of both alloys slowly increases.