Microstructure and shear strength of
reactive brazing joints of TiAl/Ni-based alloy
reactive brazing joints of TiAl/Ni-based alloy
(1. State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China;
2. School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001, China)
2. School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001, China)
Abstract: Reactive brazing of TiAl-based intermetallics and Ni-based alloy with Ti foil as interlayer was investigated. The interfacial microstructure and shear strength of the joints were studied. According to the experimental observations, the molten interlayer reacts vigorously with base metals, forming several continuous reaction layers. The typical interfacial microstructure of the joint can be expressed as GH99/ (Ni, Cr)ss (γ)/TiNi (β2)+TiNi2Al (τ4)+Ti2Ni (δ)/δ+Ti3Al (α2)+Al3NiTi2 (τ3)/α2 +τ3/TiAl. The maximum shear strength is 258 MPa for the specimen brazed at 1000 °C for 10 min. Higher brazing temperature or longer brazing time causes coarsening of the phases in the brazing seam and formation of brittle intermetallic layer, which greatly depresses the shear strength of the joints.
Key words: TiAl; Ni-based alloy; reactive brazing; interfacial microstructure; shear strength