Abstract
Both a Cu–26 wt % Ag (Fe-free) alloy and Cu–26 wt % Ag–0.1 wt % Fe (Fe-doping) alloy were subjected to different heat treatments. We studied the precipitation kinetics of Ag and Cu, microstructure evolution, magnetization, hardness, strength, and electrical resistivity of the two alloys. Fe addition was incapable of changing the precipitation kinetics of Ag and Cu; however, it decreased the size and spacing of rod-shaped Ag precipitates within a Cu matrix, because Fe might affect the elastic strain field and diffusion field, suppressing the nucleation of Ag precipitates. Magnetization curves showed that γ-Fe precipitates were precipitated out of the Cu matrix, along with Ag precipitates in Fe-doping alloy after heat treatments. The yield strength of the Fe-doping alloy was higher than that of the Fe-free alloy, and the maximum increment was about 41.3%. The electrical conductivity in the aged Fe-doping alloy was up to about 67% IACS (International Annealed Copper Standard). Hardness, strength, and electrical resistivity were intensively discussed, based on the microstructural characterization and solute contributions of both alloys. Our results demonstrated that an increasing fraction of nanoscale γ-Fe precipitates and decreasing spacing between Ag precipitates resulted in the increasing strength of the Fe-doping alloy.
Highlights
High-strength, high-conductivity materials are required extensively in the construction of high-field magnets [1,2]
The microstructure of a Cu–Ag alloy with more than 6 wt % Ag is composed of a Cu matrix, embedded by Ag precipitates and eutectic colonies [11]
The strength of the Cu–Ag alloy can be increased by refining Cu dendrites and Ag precipitates [10]
Summary
High-strength, high-conductivity materials are required extensively in the construction of high-field magnets [1,2]. Cu and Cu–X alloys (X = Ag, Fe, Nb, Cr, etc.) have attracted considerable attention as winding conductors, owing to their superior combinations of strength and electrical conductivity [3,4,5,6]. Cu–Ag alloys have been widely involved in all of these materials [7,8,9,10]. The strength of the Cu–Ag alloy can be increased by refining Cu dendrites and Ag precipitates [10]. Zuo et al [12] investigated the contributions of individual microstructures to the strength and electrical conductivity of Cu–28 wt % Ag composite, and revealed that the spacing of Ag precipitates took a dominant role in the two properties [12]
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