The microstructure and mechanical properties of YT5 cemented carbide/carbon-carbon composite joints prepared by transient liquid phase diffusion bonding using Ni/Cu/Ti multiple foils as joining materials

Abstract

YT5 cemented carbides have been successfully joined to carbon-carbon (C–C) composites by transient liquid phase (TLP) diffusion bonding technique using Ni/Cu/Ti multiple foils as joining materials. The microstructure and mechanical properties of YT5/C–C composite joints are characterized and analyzed by electronic microscopy (SEM) with an energy disperse spectroscopy (EDS), X-ray diffraction (XRD) and general mechanical testing method. The results showed that multilayer gradient structure, i.e. YT5/Ti–C compounds/Ti–Ni + Ti–Cu compounds/C–Ti–W solid solution/C–C, was formed in the joints prepared by TLP diffusion bonding with the joining temperature changing from 960 to 1020 °C. There are various compounds including TiC, Ni2Ti, Cu4Ti3, Cu3Ti2 and Ti8C5 in the joints, and all interfaces were continuous and dense by element diffusion and chemical reactions during joining process. The average shear strength of joints prepared under 990 °C, 30 min achieves 21.4 MPa. Combined with shear morphology, load-displacement curves and phases on fracture surface, it can be inferred that fracture occurs in the interface region adjacent C/C composites side and presents a brittle fracture mode.