Temperature effects on tensile behaviors and relevant deformation mechanisms of a low-cost nickel-based single crystal superalloy containing 1.5% Re

In this work, tensile properties and relevant deformation mechanisms were investigated particularly in a novel low-cost second-generation nickel-based single crystal superalloy containing 1.5 wt. % Re. The results showed that the experimental alloy exhibited an anomalous yielding phenomenon. The yield strength of alloy reached a peak value of 1120 MPa but the corresponding elongation was only 8.2% at 760 °C. Furthermore, the double yield phenomenon occurred at 900 °C and above whereas the strain softening behavior appeared at high temperatures. With increasing temperature, the main fracture mode gradually evolved from pure shear to microvoid accumulation fracture. The dislocations sheared into γ′ particles and led to the formation of stacking faults, which was the dominant deformation mechanism below 760 °C. Particularly, the formation of both K-W locks and L-C locks is closely related to the peak yield strength of the alloy at 760 °C. At 900 °C, the tensile deformation was controlled by the combination of APBs shearing and Orowan bypassing γ′ particles. As the temperature further increased to 1000 °C and 1100 °C, the dislocation networks formed on γ/γ′ interface could hinder the dislocations shearing into γ′ particles. Meanwhile, Orowan bypassing and dislocations climbing became the dominant deformation mechanisms. The results of this work could provide vital support for development and application of low-cost SX superalloys. • Anomalous yield behavior occurred obviously during tensile tests. • Strain softening behavior occurred at 1000 °C and above. • Lomer-Cottrell locks and K-W locks both could improve yield strength at 760 °C. • The alloy had excellent tensile properties and the total cost was decreased by about 40%.