Intermediate temperature creep of directionally solidified Ni-based superalloy containing local recrystallization

[Display omitted] ▶ The creep rupture life decreased rapidly with the increase of TRF. ▶ Shorter secondary creep regimes and higher creep rate of RX specimen were observed. ▶ The whole RX region had been cracked at the primary creep stage. ▶ A number of slip lines formed at the steady state creep stage. ▶ The process of crack initiation and propagation depends on the temperature and stress. Intermediate temperature creep of directionally solidified Ni-based superalloys containing local recrystallization (RX) was studied. A sharp reduction of the creep rupture life was observed with increasing the transverse RX area fraction on the cross section of the specimen. Creep curves of specimens containing local RX showed that the steady state creep stage was much shorter than that of the “good” specimens. The creep rates were also slightly higher when there was local RX. The creep and failure mechanism was discussed based on the dislocation morphology in the vicinity of the RX grain boundaries and the formation and propagation of cracks in the RX region according to the microstructure observation of the interrupted creep specimens.