A novel hierarchical structure of in-situ copper matrix composites reinforced with micro-clusters of TiB2 particles and nano-precipitates of B24Cu particles

Abstract

Copper-based materials strengthened by a second phase are widely used in electrical industrial devices due to their high strength and high electrical conductivity. However, traditional uniformly dispersed materials have inherent limitations, which restrict their overall performance. Here, we develop a new hierarchical structure strategy to overcome this issue in copper-based materials by combining in-situ synthesized copper matrix composite powders with routine powder metallurgy processes. Based on the rapidly solidified microstructure of the composite powder, the submicron TiB₂ particles with a high volume fraction formed by a liquid state in-situ reaction distribute as micro-clusters, while the nano-precipitates of B₂₄Cu particles with high thermal stability precipitates during the sintering stage and is dispersive and homogeneously distributed. This novel hierarchical structure exhibits extraordinary work hardening capability and forms a network of low electrical resistance regions, thus leading to copper matrix composites with an ultimate tensile strength of 926 MPa and electrical conductivity as high as 79.8 % International Annealed Copper Standard, which is superior to numerous copper-based materials reinforced with ceramic second phases. The results will provide fundamental insights for the structural design of second phase strengthened copper-based materials.