Interfacial microstructure and mechanical property of SiO2-BN ceramics and Invar joint brazed with Ag-Cu-Ti active filler metal

► The diffusion of Fe and Ni from Invar has great influence on joint microstructure. ► Shear strength depends heavily on Ni3Ti and Fe2Ti brittle compounds. ► Formation mechanism of the composite TiN-TiB2 fine-grain layer was discussed. ► TiN-TiB2 fine-grain layer was the key factor in achieving a good bonding.