Temperature dependence of compressive behavior and deformation microstructure of a Ni-based single crystal superalloy with low stacking fault energy

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 degrees 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 degrees C. After that, the yield strength would increase continuously to the maximum at 800 degrees 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 degrees 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 degrees 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 degrees 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.