Hybrid effect on mechanical properties and high-temperature performance of copper matrix composite reinforced with micro-nano dual-scale particles

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.