Microstructure evolution and mechanical property of ZrC-SiC/Ti6Al4V joints brazed using Ti-15Cu-15Ni filler

ZrC-SiC ceramic and TC4 alloy were successfully brazed using a self-prepared Ti-15Cu-15Ni filler. The microstructure and mechanical property of the joints obtained at different brazing temperatures were investigated. The results indicated that Ti from the Ti-15Cu-15Ni and the TC4 reacted with the ZrC-SiC to form TiC phase adjacent to the ZrC-SiC ceramic. In the brazing seam, Ti2(Ni, Cu) intermetallic compounds zone (IMCs Zone), Hypoeutectic Zone and Hypereutectoid Zone formed. The brazing temperature affected the dissolution of TC4 into the braze filler significantly, and then determined the microstructure of the joint. The formation of α-Ti in the brazing seam could decrease the hardness and the brittleness of the brazing seam, which was beneficial to the property of the brazed joint. The joint strength reached a maximum value of 43 MPa when the joint was brazed at 970 °C and cracks propagated in the ZrC-SiC substrate near the brazing seam.