Achieving high strength and pseudo-ductility in Bf/Cu composite enabled by 3D-Gr@B4C interface-modified layer

Abstract

Improving wettability, interfacial mechanical and thermal compatibility between reinforced boron fiber and Cu are strongly desirable for developing continuous boron fiber reinforced Cu matrix (Bf/Cu) composite, which shows great potential for application in nuclear fusion reactor as a promising high-strength heat-sink material. Herein, a three-dimensional graphene network hybrid B4C (3D-Gr@B4C) coating was fabricated on B fiber by single filament chemical vapor deposition as the interface-modified layer of Bf/Cu composite. It is revealed that the 3D-Gr in 3D-Gr@B4C interface-modified layer can not only supply diffusion channel to Cu for enhancing interfacial thickness and strength, but also serve as high-thermal-conductivity network to increase TC of Bf/Cu composite from 322.3 W/m·K to 343.9 W/m·K. Meanwhile, modulus of 3D-Gr@B4C interface-modified layer lying between Cu and B can also improve the interfacial mechanical compatibility of composite. Accordingly, interface modification on B fiber using 3D-Gr@B4C layer enables tensile strength up to 1016 MPa at RT and 620 MPa at 300 °C, which are ∼1.3 and ∼1.5 times higher than the corresponding values of Bf/Cu composite, respectively. Furthermore, introducing 3D-Gr@B4C layer inhibits abrupt failure of Bf/Cu composite at small tensile strain and opens up fiber pull-outs and shearing of Cu matrix at large tensile strain, producing pseudo-ductile fracture.