Microstructure and properties of Cu-Cr-Zr alloy with columnar crystal structure processed by upward continuous casting

• A short process was developed to prepare Cu-Cr-Zr alloy with columnar crystal structure. • Columnar crystal region can be controlled by the traction speed and cooling rate. • Columnar crystals and primary phases have genetic characteristics. • Zr element can restrain the growth of recrystallized grains and refine grains. In this paper, the microstructure and properties of the upward continuous casted Cu-Cr-Zr alloy during thermo-mechanical treatment are investigated. Columnar crystal structure was formed in the alloys along the upward direction by controlling the traction speed and cooling rate. Due to the genetic characteristics of the columnar crystal structure during the thermo-mechanical treatment, the microstructure of the alloys was optimized, and the grains were obviously refined after cold drawing. The results show that a large amount of columnar crystal structure can be obtained when the traction speed was 4 mm/s and the mechanical properties of the alloy were significantly improved by the columnar crystal structure and the increase of Zr content. The alloy with columnar crystal structure and higher Zr content possesses higher tensile properties, while the electrical conductivity remained relatively stable. The ultimate tensile strength (UTS) of the Cu-0.62Cr-0.34Zr alloy was 587.8 MPa after 80% cold drawing, which is significantly higher than that of the Cu-0.56Cr-0.07Zr alloy (517.7 MPa). Additionally, the grain refinement mechanism and strengthening mechanism are discussed and concluded.