Combining severe plastic deformation and precipitation to enhance mechanical strength and electrical conductivity of Cu–0.65Cr–0.08Zr alloy

Abstract

Cu–0.65%Cr–0.08%Zr alloys display a superior combination of mechanical and electrical properties than pure copper. This is due to the solid solution hardening solubility of Zr and Cr as low content alloying elements in copper. However, for some applications, such as coils for high-power magnet, a CuCrZr alloy needs a mechanical strength substantially improved as well as good electrical conductivity. The main objective of this work is to investigate the influence of an equal channel angular pressing processing followed by aging heat treatment in the microstructure, mechanical and electrical properties of a CuCrZr commercial alloy. This procedure produced a very refined microstructure with high dislocation density in association with finely dispersed precipitates and minimum amount of elements in solid solution in the Cu matrix. The mechanical and electrical properties of the alloy were evaluated by Vickers hardness while the electrical conductivity was measured using the 4-point technique. The microstructural evolution was accompanied by the grain size measurements distribution, using backscattered electron diffraction (EBSD). Dislocation density was disclosed via X-ray diffraction (XRD). The alloy presented a remarkable improvement both in mechanical strength from 53 to 562 MPa and hardness from 96 to 192 HV/10, as well as sensible increase in electrical conductivity from 82% to 92% IACS. The resulting microstructure was characterized by an average smaller grain size of 0.7 μm and a higher dislocation density of 1014 m−2. These results reveal a promising potential for applying this commercial alloy in coils of high-power magnets.

Keywords

• CuCrZr
• Electrical conductivity
• Mechanical strength
• ECAP
• EBSD
• DRX