Microstructural evolution of Si3N4/Ti6Al4V joints brazed with nano-Si3N4 reinforced AgCuTi composite filler

Abstract A novel nano-Si 3 N 4 particle reinforced AgCuTi composite filler (AgCuTi C ) was used to braze Ti6Al4V and Si 3 N 4 ceramic in the study and brazing cycles that peak at 880 °C for 0–20 min. Effects of holding time on interfacial microstructure and mechanical property were studied by scanning electron microscopy, energy dispersive spectrometer, transmission electron microscopy, and universal testing machine. TiN and Ti 5 Si 3 were identified as the main product of the reaction between Si 3 N 4 and Ti. The interfacial microstructure evolved considerably with joining time, eventually leading to a high degree of inhomogeneity across the length of the joint, and the maximal shear strength of 78.3 MPa was obtained when the joint was brazed at 880 °C for 10 min. A limited number of Si 3 N 4 /Si 3 N 4 and Ti6Al4V/Ti6Al4V joints using AgCuTi C with different content of Ti particles were also studied to clarify the influences of diffusion and dissolution behaviors of element Ti on interfacial microstructure. In terms of characterizing the interfacial phases, efforts were made to understand the microstructural evolution mechanism of Si 3 N 4 /Ti6Al4V brazed joints.