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 small amounts of Ag were systematically investigated. While a typical heterogeneous nanostructure (HN) 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 (GBS) of Ag, which enabled sufficient age hardening. The GBS 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 or over 30% IACS. Maximum tensile strength achieved was 990 MPa with 34.5% IACS for Cu–30 mass%Zn–1 mass%Ag alloy.

 

This Paper was Originally Published in Japanese in J. Japan Inst. Copper 61 (2022) 1–8. Figure 1 and Table 3 were slightly modified from the original version.

Fig. 8 Stress–strain curves obtained by tensile tests along the transverse direction. The 90% rolled specimens were first peak aged at (a) 523 K and (b) 573 K, followed by additional 20% reduction and secondary peak aging at 473 K. The specimen names and their chemical compositions are described in Table 1.