Interface regulation and properties of boron nitride nanosheets reinforced copper matrix composites

Copper has a wide application prospect in brush and contact materials because of its high conductivity and high ductility. With the rapid development of power transmission industry, the disadvantage of low strength of copper itself cannot meet the demand, and it is urgent to develop a high-strength and high-toughness copper matrix composite material (CMCs) to make up for the defects of copper materials. Boron nitride nanosheets (BNNSs) is expected to be used as good reinforcements for copper matrix composites due to its excellent mechanical properties and high temperature structural stability. In this study, BNNSs reinforced copper matrix composites (BNNSs/Cu) with high comprehensive properties were prepared by powder metallurgy. Microstructure and interface evolution characteristics of composites at different heat treatment temperatures, as well as the changes of mechanical, electrical and tribological properties were studied. The results show that by matrix microalloying (adding 1wt%Ti) and heat treatment, the dense and uniform TiN interfacial transition layer and nano-TiB whisker are formed at the interface of BNNSs, which improve the interfacial bonding between BNNSs and matrix. Ultimate tensile strength (UTS) of BNNSs/Cu-(Ti)-900℃ is 408 MPa, the elongation (EL) is 15.5% and the conductivity remains high level of 91% International Annealed Copper Standard (IACS) and the friction coefficient is 0.58 (pure Cu is 0.8). BNNSs/Cu-(Ti) prepared in this study display excellent mechanical properties and wear resistance while maintaining good conductivity, which provide the technical guidance for high performance electrical materials.