This study aimed to compare the dynamic microstructure evolution and the creep mechanical properties of second-generation nickel-based single-crystal superalloys at 780 degrees C/720 MPa and 850 degrees C/720 MPa. A method based on in situ scanning electron microscopy creep testing was used to identify the occurrence of slip bands. At the same time, the deformation mechanisms at 780 degrees C and 850 degrees C were discussed. The creep life at 780 degrees C was longer, almost five times that at 850 degrees C. Moreover, significant necking occurred in the primary creep at 780 degrees C, which controlled the entire creep process and accounted for almost 50% of the total life. In comparison, the primary creep at 850 degrees C was obviously shortened, mainly showing the characteristics of the second and third stages; the necking was mainly concentrated in the later stage of creep. This difference must be caused by the dislocation motion. The slip deformation mainly occurred at 780 degrees C, and the dislocations shearing gamma ' strengthening phase left obvious slip bands on the surface. The dislocations moved in the matrix channel in the early stage of creep at 850 degrees C, and the dislocations sheared gamma ' strengthening phases in the later stage of creep while leaving obvious slip bands on the surface.
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