ANNEAL HARDENING EFFECT IN A CAST CuAl4Zn4 ALLOY DEPENDENCE ON THERMOMECHANICAL TREATMENT

The investigations were carried out on the cast samples of Cu-4at%Al-4at% Zn alloy, as well as pure copper samples for the sake of comparison. Cast samples of alloy and copper were subjected to the same thermomechanical treatment. The thermomechanical treatment included the homogenized annealing at 850 0 C for 24 h. After that the samples were carried out to the prefinal cold rolling and than to solution annealing at 450 0 C for 2 h followed by an ice-water quenching and than cold rolling with 30 %, 50 % and 70 % in final reduction. The alloys in the cold rolled state were primary isochronally annealed up to the recrystallization temperature in purpose of investigation anneal hardening effect. Some of annealed samples of alloys were subjected again to the final cold rolling with 50 % in reduction. After that the cold rolled alloys were secondary annealed up to the recrystallization temperature in purpose of investigation anneal hardening effect after secondary annealing. Influence of thermomechanical treatment on the anneal hardening mechanism of a cast Cu4at%Al-4at% Zn alloy has been investigated for the hardness and electrical conductivity measurements. The investigations has shown that the anneal hardening effect appeared in the cast Cu4at%Al-4at% Zn alloy after primary as well as after secondary annealing and was followed by an increase in the hardness and electrical conductivity. The anneal hardening effect appeared in the temperature range of 150-400 0 C after primary annealing as well after secondary annealing but with