Effects of Co-based Fillers on Interfacial Microstructure and High Temperature Strength of SiC_f/SiC/ GH4950 Superalloy Joints

With the improvement of aircraft engine performance, the service temperature of hot end components has exceeded 1000 ℃. To improve the high-temperature mechanical properties of SiC_f/SiC/GH4950 joints, two new Co-based fillers were designed. The typical interfacial microstructure of the joints is SiC_f/SiC/NiAl_x+Ni₂Si+(Co,Ni)+ (Ni, Cr, Co, W)_ss+Co_xCr_y/GH4950. The increase of Fe element in Co-based fillers can promote the formation of (γ-Fe, α-Co)_ss, thereby improving the strength of the SiC_f/SiC/GH4950 joint. The shear test show that compared with that of Ni-based fillers, the room temperature shear strength of the SiC_f/SiC/ GH4950 joint braze with Co-based fillers does not significantly improve, but its shear strength at 1000 ℃ is significantly improved, reaching 158 MPa. The presence of Co element promotes the formation of (Ni, Cr, Co, W)_ss and high-temperature strengthening phases such as Co_xCr_y at the interface, thereby improving the high-temperature service strength of SiC_f/SiC/GH4950 joints.