Creep behavior and dislocation mechanism of Ni3Al based single crystal alloy IC6SX at 760°C

The creep behavior and dislocation mechanism of Ni3Al-based single crystal alloys IC6SX with crystal orientation [001] which was prepared by seed crystal method under the testing conditions of 760 degrees C/500 MPa,760 degrees C/ 540 MPa and 760 degrees C/580 MPa were investigated. The experimental results showed that the creep properties, dislocation morphology and mechanism of this alloy were different under different stress conditions. With the stress increasing from 500 MPa to 580 MPa, the creep life decreased from more than 1000h to 32.64h. The cubic degree of gamma' phase in single crystal alloy decreased obviously and the size of gamma' phase increased. The mechanism of dislocation movement also changed with the increasing stress. It was found that after the specimen was tested under the condition of 760 degrees C/500 MPa the dislocation network prevented the movement of dislocations and it was difficult for dislocations to enter the gamma' phase from the gamma/gamma' interface. When the stress was 540 MPa, the dislocations cut into the gamma' phase by stacking fault. Furthermore, with the stress increasing to 580 MPa, the dislocation entered the gamma' phase in the form of extended dislocation and Lomer-Cottrell dislocation.