A Basic Research for Conquest Drawbacks and Further Improvement of Properties of Heterogeneous–Nano Structured Copper Alloys

Abstract

Changes in the microstructure and various properties of heavily cold–rolled Cu–Zn system alloys with added small amounts of Ag were systematically investigated. While a typical heterogeneous–nano （HN） structure was evolved in all the alloys, the texture and ratio of the microstructural components developed were slightly varied depending on the added amount of Ag and Zn. The characteristic “eye”–shaped twin domains tended to evolve more significantly with increasing addition of these elements. Thermal stability of the HN structure appeared to be improved by Ag addition. This was due to grain–boundary segregation of Ag, which enabled sufficient age hardening. The grain–boundary segregation in the HN structure also resulted in the improvement of electrical conductivity. In this way, all the alloys showed quite high–tensile strength over 900 MPa along transvers direction with superior electrical conductivity around over 30％IACS. Maximum tensile strength achieved was 990 MPa with 34.5％IACS for Cu–30 mass％Zn–1 mass％Ag alloy.