Tensile deformation behavior of a new Ni-base superalloy at room temperature

The influence of γ′ precipitate size on the tensile deformation mechanism in a new Ni-base superalloy is investigated at room temperature. In order to achieve this aim, three model microstructures are obtained by changing aging time. After tensile deformation, the substructures are characterized by transmission electron microscopy. Experimental results reveal that plastic deformation is controlled primarily by dislocations shearing γ′ precipitates in all three microstructures, and the operative shearing process evolves as a function of precipitate size. It is found that for the fine γ′ microstructure (241 nm), both stacking fault shearing and anti-phase boundary shearing operate simultaneously; in the case of the medium γ′ microstructure (446 nm), most of the γ′ precipitates are sheared by strongly coupled dislocations, leaving faulted loops within them; whereas for the coarse γ′ microstructure (597 nm), shearing occurs by the movement of small groups of dislocations. Finally, based on experimental observations, the relationship between the tensile strength and the activation of plastic deformation mechanisms is discussed.