Abstract The deformation microstructures of a new Ni-based single crystal superalloy, M 4706, have been characterized by transmission electron microscopy after interrupted tensile tests at room temperature. It is found that besides shearing of γ′ precipitates by strongly coupled dislocations, another unusual shearing process involving a single a/2 〈1 0 1〉 matrix dislocation as well as the formation of the isolated superlattice stacking fault and Shockley loop also operates actively during initial yielding. Based on experimental observations, occurrence of these different shearing processes is discussed.

The deformation behaviour of the γ′ precipitate in a directionally solidified nickel-based superalloy is investigated using microscopic observations after tensile testing at room temperature. It is found that coarse γ′ precipitates (604 nm) are sheared by strongly coupled dislocations, and some γ′ precipitates are elongated to approximately 3–6 times of their original lengths. It reveals that, at room temperature, the γ′ precipitate within the experimental superalloy has a significant plastic deformation capacity in comparison with Ni₃Al bulk alloys. Based on the experimental observations, the extraordinary plastic behaviour of the γ′ precipitate is analysed.

Two types of arc graphene sheets with different morphology and crystal structures are found, and further probed by Raman spectroscopy. Moreover, a new growth mechanism responsible for the difference of arc graphene is proposed.