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

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.