Effect of Element Re on Creep Behaviour of a Single Crystal Nickel-Based Superalloy

By means of measuring creep curves and microstructure observation, the influence of the element Re on creep behaviour of the single crystal superalloy has been investigated. Results shown that the creep resistance of nickel-based superalloy with element Re may be obviously improved and the 2% Re superalloy had lower strain rate and longer creep lifetimes compared with Re-free single crystal alloy. The activation energy and stress exponent of the 2% Re superalloy during steady state creep were measured to be Q =478.6 kJ/mol and n = 5.1 respectively. The deformed features of the 2% Re alloy during primary creep are dislocation slipping in the matrix channels, dislocation networks are formed by dislocation reaction, and creep resistance may be improved when networks on the γ/γ’ phases interfaces. In the tertiary creep stage, deformation mechanism is the super-dislocation shearing into the rafted γ’ phase.