Regulation of primary phase in Cu-Cr-Zr alloy and its effect on nano-structure and properties

Abstract

In this study, Cu-0.8Cr-0.1Zr alloy was prepared by vacuum horizontal continuous casting method. The effect of different thermo-mechanical treatment processes on the properties was studied, and the microstructure evolution at different stages of thermo-mechanical treatment were observed by SEM, EBSD and (HR)TEM. The results showed that the optimal comprehensive performance of tensile strength (803 MPa) and conductivity (76% IACS) was obtained by three-stage drawing and thermal treatment (primary 43.75% drawing and solution treatment at 950 °C for 60 min + secondary 97.2% drawing and aging at 500 °C for 30 min + tertiary 75% drawing). Through the microstructure characterization, it was found that the morphology and distribution of the Cr-rich primary phase can be regulated by solution treatment, and inherited during the thermo-mechanical treatment. It acts as a nucleation point and hard point, thereby refining the grain and improving the strength of the alloy. Additionally, it reduces the number of solid solution atoms in the matrix and prevents the loss of conductivity. Furthermore, drawing with a large amount of deformation can produce a nano-lamellar structure with high temperature stability, and drawing after high temperature aging can induce substructure formation. The combination of nano-lamellar structure and substructure further improves the strength.