Microstructural evolution and properties of Cu–20 wt% Ag alloy wire by multi-pass continuous drawing

Chu Cheng,Kexing Song,Yong Ding,Xiuhua Guo,Zhu Xiao,Dingbiao Chen,Xujun Mi,Haitao Liu,Yanjun Zhou,Baoan Wu,Haofeng Xie,Xiaoyu Shen

doi:10.1515/ntrev-2020-0108

Abstract

Abstract The Cu–20 wt% Ag alloy wire rod was prepared using three-chamber vacuum cold mold vertical continuous up-casting followed by multi-pass continuous drawing. The evolution of microstructure, mechanical property, and electrical property of the Cu–20 wt% Ag alloy wire during multi-pass continuous drawing was studied. After multi-pass continuous drawing, the continuous network eutectic structure in the longitudinal section of the as-casted rod was gradually drawn into long fibers that approximately parallel to the axial direction, while the space of the continuous network eutectic structure in the transverse section is getting smaller and smaller. Both the preferred orientation of copper and silver grains are (1,1,1). With the increase of drawing strain (η), the tensile strength of Cu–20 wt% Ag alloy wire gradually increases while the elongation gradually decreases. When the diameter is drawn to 0.02 mm (η = 11.94), the tensile strength of the alloy is 1,682 MPa and elongation is 2.0%. The relationship between tensile strength, elongation, and diameter conforms to Allometric and Boltzmann functions, respectively.

Highlights

Copper alloy and copper matrix composite materials have many advantages of good arc erosion corrosion resistance [1], wear resistance [2], high strength [3], and other special properties [4]
When the silver content is more than 10.0 wt%, the Cu–Ag alloy wire is often used as conductive material in splice pieces and precise resistance [12]
Ning et al [20] have researched the preparation of Cu–10Ag in situ nanofiber composite by large deformation, and the results show that the tensile strength of the Cu–Ag alloy wire is up to 1,190 MPa and the conductivity is 68.7% IACS

Summary

Experimental process

They were placed with a mass proportion of 4:1 in vacuum chamber I. The as-cast Cu–20Ag rod with a diameter (Φ) of 7.83 mm was prepared from casting mold with a speed of 150 mm/min by cooling after they were fully mixed [31]. The as-cast Cu–20Ag rod was continuously cold drawn from Φ 7.83 mm to Φ 0.02 mm. The drawing strain is calculated by η = ln(A0/A), where A0 and A are initial and final cross-sectional areas, respectively. Tensile mechanical tests were carried out using a AG-I250KN electronic universal materials testing machine at room temperature.

Analysis methods

Mechanical properties

Electrical properties

Conclusions