Effect of temperature on tensile behavior, fracture morphology and deformation mechanisms of Nickel-based single crystal CMSX-4

The effect of temperature on the tensile behavior and deformation mechanisms in a single crystal superalloys CMSX-4 is addressed and deduced by transmission electron microscopy in the temperature range from room temperature to 1100 ℃. It is found that the tensile yield strength reaches a peak at 800 ℃. And then, the yield strength decreases with increasing temperature. At room temperature, anti-phase boundary shearing dominates the plastic deformation. From 800 ℃ to 850 ℃, the plastic deformation mechanism is mainly controlled by stacking fault shearing. The Kear-Wilsdorf locks have also appeared. When the temperature reaches at 950 ℃, dislocation loops with anti-phase boundary shearing of the γ ′ precipitates are presented. Above 950 ℃, the plastic deformation mechanism is processed by the rafted structure of the γ ′ precipitates by-passing, i.e., Orowan by-passing and dislocation climb. Finally, according to the experimental results, the variety of stacking faults with temperatures and the relationship between the yield strength and plastic deformation mechanism are discussed. • The tensile deformation mechanism of CMSX-4 is dependent on the temperatures. • The Kear-Wilsdorf locks within γ ′ precipitates are related to higher yield strength during tensile tests at 800 and 850 ℃. • The temperature for SSFs formation under tensile tests is lower than that at compression tests. • The deformation mechanism at 950 ℃ is controlled by the dislocation loops with APB cutting through the γ ′ precipitates. • Above 1000 ℃, the deformation mechanism is controlled by the rafted structure γ ′ phase bypassing.