Uncovering the high-temperature microstructural evolution and creep-fatigue damage mechanism of CMSX-4 brazed joints

• Published in: International journal of fatigue 2023-08, Vol.173, p.107681, Article 107681
• Main Authors: Lu, Chuanyang, Qin, Zhulai, Wang, Shiyang, He, Yanming, Sun, Yuan, Gao, Zengliang, Tu, Shan-Tung
• Format: Article
• Language: English
• Subjects: Brazing; Creep-fatigue; Damage mechanism; Microstructural evolution; Nickel-based single-crystal superalloy
• ISSN: 0142-1123; 1879-3452
• DOI: 10.1016/j.ijfatigue.2023.107681

•Zone I of CMSX-4 brazed joint without aging consists of γ + γ′, borides and silicides.•Boride and silicide in Zone I show opposite microstructural trends with aging time.•Second hardening peak occurs prior to the creep-fatigue fracture of brazed joint.•Creep void and fatigue crack are apt to initiate from matrix/precipitate interfaces. Brazing is a promising joining technique for nickel-based single-crystal superalloy (Ni-SXs) intended for turbine blades, which endure the creep-fatigue conditions. In this work, the high-temperature microstructural stability and creep-fatigue damage mechanism of brazed joint are studied. The microstructural evolution of brazed joint, especially Zone I, where the creep-fatigue failure occurs, is influenced by the aging duration. The governed creep-fatigue damage mechanism is correlated with the strain amplitude and microstructural evolution in the brazed joints. The results obtained will be beneficial to improve the joining quality of Ni-SX brazed joints used for turbine blades.