Ni-based single crystal superalloys are widely used for turbine engine blades because of their excellent high-temperature mechanical properties.Thermo-mechanical fatigue(TMF)is a complex deformation process that combines strain and temperature effects.This process is also considered as a deformation method related to the working conditions of aviation turbine blades.Therefore,understand-ing the deformation mechanism of materials undergoing TMF is important for extending the service life of aviation turbine blades.Here,third-generation and fourth-generation single crystal superalloys that experi-enced TMF deformation are investigated by SEM and TEM,including aberration-corrected STEM.The re-sults show the formation of deformation twins on different{111}planes of the single crystal superalloys.In addition,a large number of recrystallized grains are found in parallel twin lamellae or around the intersec-tion of twin lamellae.The grain boundary of recrystallized grains is primarily composed of twin boundaries,low-angle grain boundaries,and large-angle grain boundaries generated by twin intersections.Further-more,the twinning boundaries after deformation are analyzed using aberration-corrected TEM.Conse-quently,the process of twinning-induced dynamic recrystallization is comprehensively understood,which improved the TMF fracture mechanism of single crystal high-temperature alloys.These results improve the understanding of the deformation mechanism of single crystal superalloys under service conditions.
关键词
镍基单晶高温合金/热机械疲劳/像差校正透射电镜/孪晶/再结晶
Key words
Ni-based single crystal superalloy/thermo-mechanical fatigue(TMF)/aberration-corrected transmission electron microscope/twin/recrystallization
维普
万方数据