BNi-2非晶钎料钎焊高铌TiAl合金与GH3536合金接头组织与性能

High Nb containing TiAl alloy and GH3536 superalloy is brazed successfully by using amorphous BNi-2 filler metal and sound joints were obtained. The typical interfacial microstructure of the brazed joint consists of TAN substrate/B2+τ3/τ4+(Ni-Ti)-B/γ+(Ni-Ti)-B+CrB+G phase/GH3536 superalloy. The effects of brazing temperature on the interfacial microstructure of joints are then investigated. The results show that the diffusion of element B in BNi-2 and the dissolution of the elements from GH3536 alloy into the liquid brazing alloy play a crucial role in the evolution of the interfacial microstructure. With the increase of brazing temperature, the diffusion zone IV gradually disappears and the joint changes from four areas to three. It appears that the thickened τ3/τ4 compound layer and the brazing seam coarsened the black CrB phase, reducing the content of small dots (Ni, Ti)-B. After 10 min at 1160℃, the optimal shear strength of the joints at room temperature and high temperature (700℃) is about 106.8 MPa and 76.2 MPa, respectively, decreasing by about 28.6%. All the brazed joints exhibit a brittle fracture mode after the shear test. The process of joint formation can be divided into four stages: solid phase diffusion, liquid phase formation, isothermal diffusion solidification, and residual liquid phase precipitation.