Abstract: High strength and conductivity (HSC) copper alloys with excellent high-temperature softening resistance are critical for applications such as high-power electrical connectors and controlled nuclear fusion. In this study, a Cu-1.0Cr-0.4Zn-0.1Zr-0.05Si alloy with an initial heterogeneous structure was prepared by an intensive plastic deformation (IPD) method (solution treatment followed by rotary swaging and aging). The IPD-prepared Cu-Cr-Zn-Zr-Si alloy exhibited a softening temperature of 640 °C, outperforming existing HSC copper alloys. To investigate the effect of the initial deformation structure on the resistance to softening, in-situ high-temperature electron backscatter diffraction was used to observe the recrystallization behavior. The initial multi-oriented heterogeneous fibrous structure was formed by alternating <111>//LD and <100>//LD deformation bands, which induced an uneven stored energy distribution and led to partial recrystallization. Johnson-Mehl-Avrami-Kolmogorov (JMAK) kinetic analysis indicated that this structural feature significantly reduced the softening rate in the later stages of recrystallization. Furthermore, IPD facilitated the transformation of <111>//LD deformation bands into <100>//LD recrystallized grains through annealing twinning, revealing a novel recrystallization mechanism contrary to conventional theories. Molecular dynamics (MD) simulations confirmed that this orientation transformation further promoted the recrystallized grain boundary migration. This study provides novel experimental evidence and theoretical insights into improving the high-temperature softening resistance through deformation structure design.

Key words: Recrystallization, Softening resistance, Heterogeneous structure, Copper alloy, Intensive plastic deformation