Ni-based singlecrystal superalloys are widely used as two-phase blade materialsfor aircraft engines and industrial gas turbines. The materialsare strengthened by a high volume fraction of hard cubical$\gamma'$ precipitates embedded coherently in a softer $\gamma $matrix. The materials exhibit a remarkable character that the$\gamma'$ cubic particles will transform into rafts under thecombined influence of stresses and temperatures. This raftingbehavior directly affects the creep fatigue life of Ni-basedsuperalloys. Therefore, the directional coarsening mechanism isthe key rule of precipitation hardening in Ni-based single crystalalloys. Furthermore, due to the fact that no grain boundary existsin Ni-based single crystal superalloys, some problems related withthe grain boundary, such as the weakening of grain boundary athigh temperature, and the longitudinal grain boundary cracking,etc, will not occur. The dislocations motion and the structuralevolution of the misfit dislocation networks at $\gamma $/$\gamma^{' }$phase interfaces under external loading and high temperaturehave great influences on the creep mechanical properties ofNi-based superalloys. Based on the analysis of the microscopicstrengthen mechanism of Ni-based superalloys, this paper reviewsthe related researches on the directional coarsening behavior andcreep mechanical properties. It focuses on describing themicro-mechanism of the directional coarsening, driving force,interfacial microstructure evolution, creep mechanical model andthe effect of the directional coarsening on the high temperaturecreep mechanical properties. The existing problems and some topicsfor the future studies are pointed out.
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