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Microstructures and Mechanical Behaviors of Ni-Based Single-Crystal Superalloy DD90 Joints Brazed with a Co-Based Interlayer
Ist Teil von
Journal of materials engineering and performance, 2024, Vol.33 (10), p.4726-4738
Ort / Verlag
New York: Springer US
Erscheinungsjahr
2024
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
A third-generation nickel-based single-crystal superalloy, DD90, was brazed with a Co-based filler alloy under vacuum conditions. The microstructural evolution of the joints brazed with different processing parameters and their effects on the mechanical properties were studied. Many brittle compound phases were formed in the non-isothermal solidification zone, mainly consisting of M
3
B
2
and CrB. With increased bonding temperatures, the isothermal solidification zone increased in thickness and became a continuous region with the filler alloy zone (FAZ). With increasing bonding time, the alloying elements sufficiently diffused into the base metal, and the sizes of the compounds in the joint decreased. In addition, the Re contents of the M
3
B
2
and CrB phases were relatively high compared to those of the γ and γ′ phases, and Re exhibited a special diffusion mechanism and influenced the evolution in the joint microstructures. High-temperature creep rupture tests of the joints were carried out at 980 °C/75 MPa. These joints fractured in the FAZ via typical quasicleavage fracture. The cracks initiated and propagated along the brittle compounds in the FAZ, and finally, the cracks connected with each other, leading to fracture. The numbers, sizes and distribution characteristics of the compounds in the joint had a significant effect on the creep rupture life of the joint.