Microstructure and Mechanical Properties of the Heterogeneous-Nano Structured Cu–Be System Alloys

Abstract

Microstructures and mechanical properties of Cu–Be–Co alloys having four different Be contents prepared by simply heavy cold rolling (CR) were systematically investigated. The cold-rolled alloys exhibited excellent mechanical properties due to development of heterogeneous nano-structure (HN), which consisted of “eye”-shape deformation twin domains surrounded by shear bands, and they were further embedded in conventional low-angle lamellae. The strength of each alloy increased with increasing Be content. The volume fraction of the twin domains quantitatively evaluated by the texture analyses that increased with increasing Be content rapidly from 0.40 mass% to 1.27 mass% and gradually from 1.27 mass% up to 2.14 mass%. The latter stagnation was attributed to the formation of coarse intermetallic particles, which impeded the formation of the HN structure. It revealed that the strength was correlated closely with the volume fraction of twin domains.

 

This Paper was Originally Published in Japanese in J. Japan Institute of Copper 60 (2021) 81–86.

Fig. 8 Relationship between ultimate tensile strength and the volume fraction of deformation twin domains developed in 90% cold-rolled Cu–Be–Co alloys with different Be concentrations. The values of ultimate tensile strength were obtained from tensile tests performed with the stress axis parallel to RD or TD.