Abstract: A dual-scale hybrid HfB₂/Cu-Hf composite with HfB₂ microparticles and Cu₅Hf nanoprecipitates was designed and prepared. The contribution of the hybrid effect to the mechanical properties and high-temperature performances was studied from macro and micro perspectives, respectively. The hybrid of dual-scale particles can make the strain distribution of the composite at the early deformation stage more uniform and delay the strain concentration caused by the HfB₂ particle. The dislocation pinning of HfB₂ particles and the coherent strengthening of Cu₅Hf nanoprecipitates simultaneously play a strengthening role, but the strength of the hybrid composite is not a simple superposition of two strengthening models. In addition, both Cu₅Hf nanoprecipitates and HfB₂ microparticles contribute to the high-temperature performance of the composite, the growth and phase transition of nanoprecipitates at high temperature will reduce their contribution to strength, while the stable HfB₂ particles can inhibit the coarsening of matrix grains and maintain the high-density geometrically necessary dislocations (GNDs) in the matrix, which ensures more excellent high-temperature resistance of the hybrid composite. As a result, the hybrid structure can simultaneously possess the advantages of multiple reinforcements and make up for the shortcomings of each other. Finally, a copper matrix composite with high strength, high conductivity, and excellent high-temperature performance is displayed.

Key words: Copper matrix composite, HfB₂ particles, Hybrid effect, High strength and high conductivity, High-temperature performance