LAUSR

Abstract Reliable contact-reactive brazed joints of TC4 alloy and Ti 3 SiC 2 ceramic were obtained using a Cu interlayer. The interfacial microstructure of a TC4/Ti 3 SiC 2 joint brazed at 920 °C for 10 min was TC4/Ti 2 Cu + α-Ti + β-Ti/Ti 2 Cu + AlCu 2 Ti + Ti 5 Si 3 /Ti 5 Si 3 + Ti 5 Si 4 /Ti 3 SiC 2 . The interfacial microstructure and mechanical properties of TC4/Ti 3 SiC 2 joints brazed at different temperatures were investigated. With increasing temperature, the shear strength of the brazed joints first increased and then decreased. The maximum shear strength was 132 ± 8 MPa, and the corresponding fracture occurred along the Ti–Si reaction layer and the Ti 3 SiC 2 substrate adjacent to the Ti–Si reaction layer. The microhardness test also demonstrated that the Ti–Si reaction layer possessed the highest microhardness, 812 ± 22 HV. The Ti-Si reaction layer was the weakest part of the brazed joints. To eliminate the Ti-Si reaction layer and improve the mechanical properties of TC4/Ti 3 SiC 2 brazed joints, a 40-μm Ni layer was plated on the surface of the Ti 3 SiC 2 ceramic before brazing. The results showed that the Ti–Si reaction layer that formed adjacent to the Ti 3 SiC 2 ceramic was thin and intermittent. Moreover, the interface between the Ti 3 SiC 2 ceramic and the TC4 alloy became jagged. The shear strength of the TC4/nickel-plated Ti 3 SiC 2 brazed joints improved to 148 ± 8 MPa; the corresponding fracture occurred mainly in the Ti 3 SiC 2 ceramic and only a small portion of the fracture occurred in the brazing seam.