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 con ductivity and high strength is increasing to a large extent. In the pr evious studies, it was shown that the Cu-Cr in-situ composite has demo nstrated excellent mechanical and electrical properties. The aim of th e present study is to further strengthen this composite by adding a th ird element. In this work, Zr is selected as an alloying element becau se it has capacity for enhancing the precipitation hardening of the al loy. The authors prepared Cu-15 mass%Cr-0.15 mass%Zr alloy and investi gated its solidification structure, cold worked structure, and aging c haracteristics as follows. (1) A band structure and heavily deformed s tructure exist in the Cu phase due to the accumulation of drawing stra in. (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 o bservation showed that three types of precipitates exist after aging, i.e., precipitates on vacancies, dislocations and grain boundaries. Th e precipitates on dislocations contribute to the secondary hardening.