Microstructure evolution, electrical conductivity and mechanical properties of dual-scale Cu5Zr/ZrB2 particulate reinforced copper matrix composites

Abstract Cu-0.3 wt% Zr alloys incorporated with varying ZrB 2 levels were prepared by adjusting Zr/B addition rates via in-situ synthesis. Micro-scale ZrB 2 particles formed through in-situ reactions between Zr and B in copper melt and nano-scale Cu 5 Zr precipitates formed upon aging treatment. The composites thus produced exhibited desired combination of mechanical properties and electrical conductivity. This paper investigates the effects of cryorolling and aging treatment on the microstructures and properties of the composites. Compared with traditional rolling process, the ultimate tensile strength of cryorolled Cu-0.3Zr–1ZrB 2 composites increased from 541.9 MPa to 599.6 MPa without sacrificing too much electrical conductivity. The contributions of different strengthening mechanisms due to the dual-scale particles, twins, and dislocations were quantitatively calculated and the results showed good agreement with the experimentally measured data. Also revealed in this work is that the mechanical performance of Cu-0.3Zr- x ZrB 2 composites is relatively superior with respect to Cu-0.3Zr at 573 K, indicating that ZrB 2 is in favor of enhancing the resistance to thermo-softening.