Plastic deformation mechanisms in a new Ni-base single crystal superalloy at room temperature

The evolution of dislocation configurations in a new Ni-base single crystal superalloy, M4706, during tensile deformation at room temperature is characterised by transmission electron microscopy. Experimental results show that contrary to previous reports, numerous isolated superlattice stacking faults and extended stacking faults are formed in the slightly deformed specimens with and without tertiary γ' precipitates. Meanwhile, it is also found that as the plastic deformation proceeds, the dominant deformation mechanism changes from stacking fault shearing to antiphase boundary shearing. Finally, based on experimental observations, the reasons for the formation of these faults and the transition in the deformation mechanism are discussed.