Creep behavior of a single crystal nickel-based superalloy containing 4.2% Re

By means of the microstructure observation and measurement of creep properties, an investigation has been made into the high-temperature creep behavior of a single crystal nickel-based superalloy containing Re. Results show that, compared to the 2%-Re alloy, the 4.2%-Re superalloy possesses a better creep resistance in the temperature ranges of 1040–1100 °C. The apparent activation energy and stress exponent of the alloy during steady state creep are measured to be Q = 483.5 kJ/mol and n = 4.7 in the experimental temperature and stress ranges. The dislocation climbing over the rafted γ′ phase dominates the creep process of the alloy during steady state creep. In the later stage of creep, the deformation mechanism of the alloy is that the super-dislocations with [01¯1] and [0 1 1] trace directions shear into the rafted γ′ phase. The main/secondary slipping dislocations are alternately activated to twist the rafted γ′ phase up to the creep fracture, which is thought to be the fracture mechanism of the alloy during creep.