Fabrication of high-temperature resistant SiCf/SiC-GH4950 joint using a novel Co-based HEA filler: Interfacial interaction and mechanical properties

Thrust-to-weight ratio of aeroengines has been steadily increasing, thereby putting more stringent requirements on the heat-resistance of hot-section components. Currently, the filler for Ceramic Matrix Composites (CMCs)/superalloys faces a critical issue: insufficient high-temperature performance above 900 ℃, which restricts their application in next-generation propulsion systems. To address this challenge, this study developed a Co-based High-Entropy Alloy (HEA) for achieving a high-temperature-resistant bond between SiC f /SiC composite and GH4950 superalloy. The resulting brazed seam consists primarily of Ni-Si compounds, graphite, carbides, W-based HEA, (Ni, Co) 3 (Al, Si) and (Ni, Co) 3 (Si, Ti) compounds, all contributing to exceptional high-temperature performance. Thus, at 1 000 ℃, the shear strength of SiC f /SiC-GH4950 joint can be maintained at 69 MPa. Furthermore, the influence of brazing temperature on the microstructure and mechanical properties of the SiC f /SiC-GH4950 joint was investigated. As the temperature ascended, the weak regions of ((Ni, Co) 2 Si+graphite)/Ni 31 Si 12 layered structure vanished, and the interface of SiC f /SiC/brazing seam transformed from straight to wavy, forming an interlocking structure that significantly enhanced the shear strength. When brazed at 1 220 ℃ for 10 min, the room-temperature strength of the SiC f /SiC-GH4950 joint reached a maximum of 114 MPa. Overall, this study offered a strategy for manufacturing heat-resistance CMCs/superalloys components by Co-based HEA filler.