Effect of Re on low-cycle fatigue behaviors of Ni-based single-crystal superalloys at 900 °C

The effects of Re on low-cycle fatigue (LCF) behaviors of single-crystal superalloys can be summarized mainly in the following aspects. On one hand, the addition of Re strongly retards the coarsening process of γʹ-Ni3Al phase and maintains the uniformity of the phase structure. On the other hand, the Re addition can promote the segregation, which usually increases the lattice mismatch of the superalloy and further impedes any individual dislocation to move in the γ-Ni matrix freely and induces the activation of more dislocation movement by a combined glide-climb process. All these factors have improved the LCF properties of single-crystal superalloys at 900 °C, for instance, the deformation becomes more homogeneous, the strengthening of γʹ phase is more effective and therefore the fatigue life becomes longer due to the addition of Re.