Temperature dependence of compressive behavior and deformation microstructure of a Ni-based single crystal superalloy with low stacking fault energy
(1. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China;
2. Development Institute of Northwestern Polytechnical University in Shenzhen, Northwestern Polytechnical University, Shenzhen 518057, China;
3. Xi’an Aerospace Engine (Group) Co., Ltd., Xi’an 710021, China)
2. Development Institute of Northwestern Polytechnical University in Shenzhen, Northwestern Polytechnical University, Shenzhen 518057, China;
3. Xi’an Aerospace Engine (Group) Co., Ltd., Xi’an 710021, China)
Abstract: The effect of temperature on the compressive behavior and deformation mechanism of a Ni-based single crystal superalloy with low stacking fault energy was investigated in the temperature range from room temperature to 1000 °C. The results indicated that both the compressive behavior and deformation microstructure were temperature- dependent. There was a higher yield strength at room temperature and then the yield strength decreased at 600 °C. After that, the yield strength would increase continuously to the maximum at 800 °C and then decrease rapidly. Furthermore, the deformation mechanisms were revealed by transmission electron microscope observation. The dislocation tangle and dislocation pairs pile-up were the main reasons for the higher yield strength at room temperature. At 600 °C, the transition in the deformation mechanisms from anti-phase boundary shearing to stacking fault shearing accounted for the slight decrease of the yield strength. At 800 °C, the deformation mechanism was mainly controlled by stacking fault shearing and the reaction of stacking faults along different directions as well as Lomer-Cottrell locks was responsible for the maximum yield strength. Above 900 °C, the primary deformation mechanism was the by-passing of dislocations, although there were still some stacking faults. Finally, the temperature dependence of deformation mechanism and compressive behavior was discussed.
Key words: Ni-based single crystal superalloy; dislocation structure; stacking fault; compressive behavior