The stacking fault energy and creep mechanism of a single-crystal nickel-based superalloy at different temperatures were studied. The results showed that the stacking fault energy increased with the increase in temperature, and element Ru greatly reduced the stacking fault energy compared with other elements in the alloy. The creep mechanism of the alloy was a 〈110〉 super-dislocation shearing into the γ′ phase below 850°C, and the super-dislocation could be decomposed into the configuration of (a/3) 〈112〉 partial dislocations plus super-lattice intrinsic stacking fault. The resistance of the dislocation decomposition increased during creep above 850°C, the a 〈110〉 super-dislocation did not decompose when it cut into the γ′ phase along the {111} plane.
By means of tensile creep tests and microstructure analysis, the creep behavior and deformation mechanism of a nickel-based single-crystal alloy with small-angle deviations from the [111] orientation at 1040°C/137 MPa were investigated. The results suggested that in the early stage of creep, proliferating dislocations generated by different slip systems get accumulated in the γ phase. Dislocations mainly slipped in the γ phase and climbed over the γ′ phase, and they began to form a dislocation network at the interface. γ′ phases were connected to each other, and the coherence relationship was destroyed. In the steady-state stage of creep, the solid interfacial dislocation network was formed, and the γ′ phase transformed into a lamellar raft structure, which hinders the slip and climb of dislocations in the matrix channel. In the accelerated creep stage, the dislocation network was destroyed, and dislocations sheared into the γ′ phase in the way of dislocation pairs, which could react to form a superdislocation node and decompose to form APBs on the <111> plane or cross slip from the <111> plane to the <100> plane to form K-W locks.
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