Effect of Zr on aging characteristics and strength of Cu-Cr in situ composite

The need for the development of the conductive materials with high conductivity and high strength is increasing to a large extent. In the previous studies, it was shown that the Cu-Cr in-situ composite has demonstrated excellent mechanical and electrical properties. The aim of the present study is to further strengthen this composite by adding a third element. In this work, Zr is selected as an alloying element because it has capacity for enhancing the precipitation hardening of the alloy. The authors prepared Cu-15 mass%Cr-0.15 mass%Zr alloy and investigated its solidification structure, cold worked structure, and aging characteristics as follows. (1) A band structure and heavily deformed structure exist in the Cu phase due to the accumulation of drawing strain. (2) The specimens aged between 623 and 723 Ii surpass those of the as-rolled specimens with regard to 0.2 PS and sigma(B). (3) The TEM observation showed that three types of precipitates exist after aging, i.e., precipitates on vacancies, dislocations and grain boundaries. The precipitates on dislocations contribute to the secondary hardening.