Profiling interfacial reaction features and mechanical properties of B4C ceramic and Ti6Al4V titanium alloy brazed with Ag-based brazing filler

Abstract

B4C ceramic can be used for the surface protection of Ti6Al4V titanium alloy because of its high hardness and excellent wear resistance. However, the joining of these two materials remains relatively unexplored in current research. In this study, two kinds of active brazing fillers (AgCuTi and AgCuInTi) are applied to braze B4C and Ti6Al4V. The microstructures of the ceramic interface are detailly characterized using TEM, revealing that the reaction layers adjacent to B4C are composed of nano-TiC and TiB whiskers. When AgCuTi is used as the brazing filler, the brazed joints exhibit low shear strength (16.6 MPa) and consistently fail at the ceramic side after the shear test due to the presence of large residual stress. To mitigate the residual stress in the joints, B4C and Ti6Al4V are brazed using the AgCuInTi filler with a lower melting point. The effects of the brazing temperature and the holding time on the microstructure and the mechanical property of the joints are thoroughly investigated. The results demonstrate that reducing the brazing temperature effectively alleviate residual stress in the joint and enhance its shear strength. The maximum shear strength achieved is 90.6 MPa when the joints are brazed at 720 ℃ for 10 min. The study presents a new idea for conducting dependable surface protection on the metal.