Microstructural Evolution and Tensile Properties of a Corrosion-Resistant Ni-Based Superalloys Used for Industrial Gas Turbines

As an important mechanical property, tensile behavior has been regarded as an indicator for the creep and thermal mechanical fatigue properties of Ni-based superalloys. The tensile property of Ni-based superalloys is closely related to the amount, size, and distribution of γ'-phase and carbides. To further clarify the tensile deformation mechanism of the CM247LC alloy, this study investigated its solidification characteristics and directionally-solidified and heat-treated microstructure. The dependence of tensile properties on the varied temperature ranging between 650 and 950 ℃ is discussed in detail. It was found that the deformation mechanism at 650 ℃ is dominated by the shearing of dislocations into the γ'-precipitates to form the superlattice stacking faults. At 800 ℃, the K-W lock leads to the anomalous yield effects. At 950 ℃, the deformation mechanism is dominated by the dislocations bypassing the γ'-precipiates. The results provide a comprehensive understanding of the CM247LC alloy and are beneficial for the development of corrosion-resistant Ni-based superalloys.